A very common essay prompt/discussion topic for The Great Gatsby is to have you compare and contrast a pair of characters in Gatsby. Why do teachers love these prompts so much?
These compare/contrast essays are an opportunity for you to tie the character similarities and differences to larger observations about society and class, the American Dream, or identity in the novel. They also allow you to practice standard English class skills: close reading, using lines from the text as evidence, and taking a stance and presenting a supporting argument in an essay.
We’ll go over some basic dos and don’ts for writing compare/contrast essays before diving into some analysis of the most asked-about character pairings. Keep reading if you have a Compare/Contrast assignment on the horizon!
- The do's of a compare and contrast essay
- The don'ts of a compare contrast essay
- Why some characters are paired for comparison more often than others
- Analysis of and essay topic ideas for the most common character pairs:
- Nick and Gatsby
- Tom and George
- Tom and Gatsby
- Daisy and Jordan
- Daisy and Myrtle
What to Do in a Compare/Contrast Essay
Like anything you write for English class, your essay should be clearly organized, with a thesis statement (a one-sentence summary of your argument), and topic sentences for each body paragraph.
And you should definitely have an overall argument! The point of the compare/contrast essay isn’t for you to just list the differences and similarities between two characters, you need to take those observations and make a larger argument about the novel as a whole. That larger argument allows you to practice writing an essay that contains an argument, which is a skill that nearly all English teachers are focused on building.
To take a quick example, don’t just list the differences between Tom Buchanan and Jay Gatsby. Instead, make an argument like, “Fitzgerald’s portrayal of wealthy New York society through Jay Gatsby and Tom Buchanan allows him to critique both old money and the newly rich, while reserving his most pointed critiques for the old money crowd.” (Obviously, that’s just one example, and there are dozens of potential arguments you could make while comparing and contrasting characters in Gatsby!)
Make sure to address your larger argument in each body paragraph as you draw out the similarities and differences between the two characters. Don’t get caught in the weeds as you tease out the many differences and similarities in each character pair. Always link back to the bigger picture.
Finally, analyze each quote you use – in other words, don’t stick a quote in your essay and do nothing with it. Make sure to explain how and why the quote demonstrates a key similarity or difference, and what that means for your bigger argument.
What to Avoid in a Compare/Contrast Essay
Don’t just list differences and similarities without an overarching argument. Although you can definitely start brainstorming by making a list of similarities and differences, just presenting that list in essay form won’t get you a good grade, since you need to go deeper and explain what the similarities/differences suggest about the novel as a whole.
And, on the other side, don’t make big claims without some evidence from the text to back them up. For example, don’t say “Tom is selfish while Gatsby cares about others.” Prove those two separate claims (Tom is selfish” and “Gatsby cares about others”) with relevant lines from the book. (And if you’re having a hard time locating good quotes, find a digital version of Gatsby you can search using the CTRL-F function. It’s a lifesaver when gathering relevant quotes for an essay!)
The garden gnome agrees - our essay tips have helped him out more than you'll ever know.
Why Are These Characters Paired Most Often?
We will tackle these major pairings in the next sections of this article:
- Nick Carraway and Jay Gatsby
- Tom Buchanan and Jay Gatsby
- Tom Buchanan and George Wilson
- Daisy Buchanan and Jordan Baker
- Daisy Buchanan and Myrtle Wilson
Before we dig into the analysis, you might be wondering: “why are we only comparing characters of the same gender?” or maybe “why not other pairings? Why not Jordan and Myrtle, or Nick and Tom?” We are focusing on these specific pairings because they are by far the most commonly asked about pairs in essay prompts and discussion topics for The Great Gatsby. And we want this guide, first and foremost, to be helpful to students as you work on assignments involving Gatsby!
Furthermore, these pairings help teachers get you to explore some of the novel’s larger themes. For example, comparing Daisy/ Myrtle or Tom/George can help you explore the differences between the wealthy and the working class. Comparing Daisy/Myrtle or Daisy/Jordan can help you explore the changing status of women during the 1920s. Comparing Tom and Gatsby can get at the old money/new money divide. Finally, differences between Nick and Gatsby raise some of the novel’s larger questions about the American Dream, repeating the past, and identity. In short, these pairings have become common because they each allow fairly easy access to one of the novel’s larger issues.
That’s not to say you couldn’t also explore some of those themes by comparing, say, Jordan and George, or Daisy and Gatsby, but cross-gender compare/contrast essays can be challenging because the status of women and men is so different in the novel. If you are interested in seeing how a particular male and female character are paired, you may be better off studying them through the lens of love, desire, and relationships in the novel, or through the way they relate to one of the novel's symbols or motifs.
With those thoughts in mind, let's jump into the top 5 pairings! For each pairing, we will suggest a few possible larger arguments you can either build from or disagree with, but these are far from comprehensive! You should add to our analysis of the characters and come up with an argument you’re excited about.
Quick Note on Our Citations
Our citation format in this guide is (chapter.paragraph). We're using this system since there are many editions of Gatsby, so using page numbers would only work for students with our copy of the book. To find a quotation we cite via chapter and paragraph in your book, you can either eyeball it (Paragraph 1-50: beginning of chapter; 50-100: middle of chapter; 100-on: end of chapter), or use the search function if you're using an online or eReader version of the text.
Nick Carraway and Jay Gatsby
Although Jay Gatsby and Nick Carraway vary both in outlook and temperament, they are also alike in interesting ways. Despite somewhat similar desires, attitudes, and social positions, Nick and Gatsby make very different choices during the novel.
Love and Romance. Nick and Gatsby both want women that are out of their reach, although in different degrees. Daisy is miles above Gatsby in terms of social class. Jordan and Nick are of the same social status, but Jordan doesn't seem free to make her own decisions since an aunt controls her financial life. There is a significant passion gap between Gatsby and Nick as well. Gatsby obsesses over Daisy - he has thought of nothing else for five years, going as far as to buy a house across the bay from her just in case she notices. Nick, meanwhile, is attracted to Jordan's cool and self-sufficient demeanor, but he is clearly not in love with her, as he himself notes ("I wasn't actually in love, but I felt a sort of tender curiosity" (3.159)).
Approach to Women. Both men are not particularly interested in the inner lives of the women they want to be with. Gatsby is devastated when Daisy doesn't want to renounce her relationship with Tom completely. Similarly, Nick cavalierly discounts Jordan's penchant to lie, cheat, and generally be cynically uninterested in other people, and then is deeply disappointed when she acts this way after Myrtle's death.
Class and Social Standing. Although both Gatsby and Nick are outsiders to the wealthy communities of East and West Egg, Nick is a much more in-between character socially than Gatsby. Nick is familiar with the ways of the old money crowd because of his own family's privilege and the fact that he is related to Daisy. Gatsby is not only self-made, but is a criminal who is desperate to pass as part of the old money elite without knowing its customs or rules of behavior. What isolates Nick from East Egg life is his Midwestern values and the importance he places on morality and decency. Gatsby is isolated from everyone by the fact that he can never actually be himself - he is always playing a role and putting on his "Oxford man" persona. It may be this sense of feeling out of place that connects them.
Outlook and Temperament. Gatsby is an optimist (almost to a delusional degree) while Nick is a realist who finds Gatsby's idealism inspiring and admirable. Gatsby believes in his ability to shape his own life and future, which makes sense since he has managed to transform himself from a farmer to a successful gangster, to impersonate an "Oxford man," and to accumulate a fantastic amount of wealth in a very short time. This belief in his power translates to Gatsby being sure that he and Daisy can go back to their month of idyllic love ("'Can't repeat the past?', he cried incredulously. 'Why of course you can!'" (6.129). Nick tries his best to be an objective realist and to reign in his tendency to judge others. He is deeply in awe of self-directed men like Gatsby, and even Wolfshiem (Nick is amazed to think that one man could be behind a huge event like the rigged World Series).
Ambition. Gatsby dreams of greatness. As a young man his mind “romped like the mind of God,” and so as an adult, he seems to have made good on this promise by buying the most ridiculous mansion and throwing the most extravagant parties (6.134). Nick is much less ambitious in comparison. While he comes to New York seeking excitement, he doesn't want to be the wealthiest bond salesman on Wall Street or to have the biggest house. He is happy to be an observer at the edge of the drama rather than being in its midst.
Nick and Gatsby Essay Ideas
Here are potential arguments to build on or disagree with based our observations. These are certainly not the only possible arguments, so be creative! Make sure your essay considers what the similarities and differences between Nick and Gatsby reveal about the novel as a whole.
- Nick is a passive person and Gatsby is active, which is why Gatsby is the hero and Nick simply the observer.
- Nick has much more in common with Gatsby than he thinks he does, which explains why he becomes so enamored of him.
- Nick serves as a foil (someone who serves as a contrast) to Gatsby, which makes Nick the best possible observer of Gatsby.
- At the end of the novel, Tom says that Gatsby “threw dirt in [Nick’s] eyes, just like Daisy’s,” meaning that both Nick and Daisy were taken in and could never see the true Gatsby: a narcissist and a criminal. Tom is right - the whole novel is Nick trying to spin a negative character into a positive one.
Nick Carraway: master of spin or just along for the ride?
Tom Buchanan and Jay Gatsby
As they battle over Daisy’s love, Tom Buchanan and Jay Gatsby sometimes seem surprisingly similar - particular in their self-centeredness, wealth, and concern with appearances. At the same time, these surface parallels point to major conflicts in their social class, and say a lot about the world of the novel.
Appearance. Gatsby is driven by his materialism to be very invested having fashionable clothes, a beautiful mansion, and visually overwhelming parties - for him, the outfit is the thing that makes the Oxford man. Meanwhile because Tom doesn't have to dress the part of the moneyed elite to be one, he is instead very attuned to the behavior of others. This is why he immediately sees how fake Gatsby's persona is, both because of Gatsby's overly ostentatious clothes, and because of how much Gatsby misreads the fake invitation from the Sloanes. Tom is never fooled into thinking that Gatsby is anything other than an upstart, and mostly likely a criminal one.
Self-Centeredness. Tom and Gatsby are both completely selfish, and fully convinced that their desires have to be acquiesced to by those around them. Tom, for example, starts his affair with Myrtle by pressing himself against her on a train platform - basically, his version of flirting is bodily assault. Gatsby, meanwhile, also thinks nothing of starting an affair with a married woman, assuming that his obsessive feelings are enough to justify any behavior.
Wealth. Despite the fact that both are unimaginably rich, these men come from totally different sides of the big money divide. Tom comes from old money and is forever worried about the encroachment of the nouveau riche, minorities, and others onto what he thinks is his. At the same time, Gatsby is the most successful of the novel's many ambitious social climbers, using his lack of ethical scruples to parlay his criminal activity into a higher social status.
Power. Tom loves being powerful and wields his power directly. He is physically aggressive and uses his body to threaten and intimidate (Nick, for one, is clearly very cowed by Tom's bulk). He is also quick to violence, whether it's socially sanctioned - like his football accomplishments - or not - like when he breaks Myrtle's nose without a second thought. Gatsby also holds significant power, but his methods are much more indirect. Still, whether he is offering Nick some illegal bond trading action, or showing off his get-out-of-a-ticket-free card to a cop on the highway, Gatsby is clearly happy to be in control of a situation.
Love. Tom and Gatsby both seem to be in love with Daisy. But what does that really mean to each of them? For Tom, Daisy is clearly partly appealing because she completes his horse-riding, East Egg, 350-thousand-dollar pearl necklace lifestyle. He cheats on her because he clearly has never denied himself anything, but he also understands Daisy as a person. He knows that she is too weak to leave him, but he also loves her enough to tolerate her affair with Gatsby and to stay with her after Myrtle's murder. Gatsby's love, on the other hand, is in some ways purer because he so idealizes Daisy and connects her to all of his other hopes and dreams. But this love is overly pure - he doesn't really seem to know Daisy as anything other than an idealized object, and is incapable of accepting that she has led a life apart from him for five years.
Tom and Gatsby Essay Ideas
In a compare/contrast essay, you can’t just present a list of similarities and differences. You also need to have an underlying argument you’re supporting. Feel free to take these at face value or as jumping-off points for your own thoughts.
- Tom loves Daisy as a person, Gatsby loves her as an idea.
- Both Tom and Gatsby’s tendency to control women and see them as prizes reveals the misogyny of the 1920s.
- Although Tom sees Gatsby as someone from an entirely different class than him, what they have in common (selfishness, affairs, obsession with appearances) makes a larger argument for an overall moral hollowness of the rich of any class.
- We see both Gatsby and Tom through the eyes of Nick, who worships one of them and hates the other. In reality, they are both much more similar than different, and their different treatment reveals Nick's insecurities and biases.
Gatsby gives new meaning to letting perfect be the enemy of the good.
Tom Buchanan and George Wilson
At first, most readers see Tom Buchanan and George Wilson as opposites. But, these markedly different characters face very similar circumstances and offer two takes on masculinity and power in the novel.
Appearance and Presence. Where Tom is strong and cowering, George is meek and shrinking. Tom exudes power and confidence while George tends to just fade into the background. These differences are borne out in the way these two men interact with the world. Tom is violent towards others, while George’s instinct is to be passive or to try and escape situations, the notable exceptions being his locking up of Myrtle and murder of Gatsby. Tom is confident, privileged, and assured while George is timid; George is “ruled by his wife” where Tom is selfish and acts on his own desires.
Reaction to Adversity. There is a dramatic difference in the way the two men react to the fact that their wives are cheating on them. Tom notices Daisy’s love for Gatsby and immediately starts making power plays. On the other hand, George discovers Myrtle’s affair and is undone by it. Nick compares the two men in a memorable description:
“the shock had made him physically sick. I stared at him and then at Tom, who had made a parallel discovery less than an hour before--and it occurred to me that there was no difference between men, in intelligence or race, so profound as the difference between the sick and the well. Wilson was so sick that he looked guilty, unforgivably guilty--as if he had just got some poor girl with child" (7.160).
In this description, Tom is “well” and George is “sick.” These are certainly arresting ways to describe Tom's more traditional masculinity and George's less overtly masculine character. Tom is self-assured in the face of adversity and immediately takes action to win Daisy back, insisting on driving Gatsby's car, bullying those around him into driving to Manhattan, and using his romance skills to remind Daisy of the pluses of their relationship. Meanwhile, George's weakness makes him look sick and guilty as he contemplates Myrtle's betrayal and is driven to violence to reassert his power over her.
Approach to Women. Both Tom and George assume they know what’s best for their wives: Tom dismisses Daisy’s professed love for Gatsby despite their obvious closeness, while George is determined to take Myrtle out west once he learns about the affair. But, while it seems that Tom does fundamentally understand Daisy and is right about her unwillingness to leave their marriage, George is unable to hold on to Myrtle either emotionally or physically. She is killed trying to run away from him.
Tom and George Essay Ideas
Differences in attitude and outcome, despite a relatively similar situation, reveal some unexpected truths about the world of the novel. Argue the reverse of any of these topics for a really provocative essay!
- The fact that Tom manipulates George into killing Gatsby and then himself (which allows Tom and Daisy to walk away from the entire affair without consequence) shows the huge privileges of having money in the novel.
- Nick's approach to Tom and George shows his admiration of a physical, brutish, domineering kind of masculinity.
- The fact that the relatively good guy turns into a murderer while the bad guy lives to cheat another day is a very cynical take on what happens in a world without a moral compass.
Perhaps it shouldn't be surprised that the meeker man turns out to be the ultraviolent one.
Daisy Buchanan and Jordan Baker
Despite Daisy Buchanan and Jordan Baker's similar “white girlhoods” (1.140) in Louisville, their attitude and motivations are quite distinct, making them really interesting to compare and contrast.
Attitude and Outlook. Both Daisy and Jordan display an entitled, bored attitude that’s typical of Fitzgerald’s depiction of the old money segment of wealthy New York society. The fact that they are introduced in tandem, both lying on the couches in their white dresses, speaks to their initially similar attitudes. But soon we see how different their takes on this kind of life are. Daisy is increasingly despondent, even nihilistic, asking in Chapter 7, “what shall we do today, and tomorrow, and for the next thirty years?” (7.74). Jordan meanwhile is a pragmatic opportunist, who sees possibilities everywhere, arguing that “life starts all over again when it gets crisp in the fall” (7.75). In other words, Daisy’s pessimistic attitude from Chapter 1 comes through again, while Jordan, despite coming across as cynical and sharp, actually still seems excited about the possibilities life has to offer.
Appearance and Personality. Both Daisy and Jordan very alluring in their own way, though Daisy’s allure comes through her enchanting voice and feminine charms, while Jordan is masculine, “jaunty,” witty, sharp, and physical. Daisy maintains a squeaky-clean reputation despite moving with a fast crowd, while there are plenty of rumors about Jordan’s cheating in golf, and Nick comments on her dishonest attitude. More significantly, Daisy is incredibly self-absorbed while Jordan is very observant.
Role in Society. Daisy seems caught between what society expects of her and some deeper, more powerful desires she can’t name, resulting in restlessness, depression, and her affair. Daisy is sticking to her prescribed societal role by marrying and having a child, while Jordan plays golf, “runs around town” and doesn’t seem to be in a hurry to marry, at least in the beginning of the novel. Perhaps Jordan is still somewhat optimistic about the possibilities of life since she hasn’t settled down yet, while Daisy realizes that nothing major in her life will change at this point. Jordan, meanwhile, is content to chase after fun and intrigue via other people’s bad behavior. And she doesn’t get dragged down by the tragedy in the book – on the contrary, she is callous in how little Myrtle’s death seems to shake her, coolly calling Nick the next day and asking him to meet like nothing has happened (8.50-61). Perhaps her motivations are a bit less accessible to the reader since her role was significantly downsized between some of Fitzgerald’s earlier drafts. But in any case, as we watch Daisy struggle in her marriage, what we see of Jordan is cool, calm, collected, and rather uncaring.
Daisy and Jordan Essay Ideas
So what are some possible conclusions we can draw from Daisy and Jordan’s characters? One of the most common strategies is to tie the differences between these women onto one of the book’s larger themes, like the role of society and class or the American Dream. Another is to think about an important feature of the novel, like Nick’s narration, and see what these two characters can reveal about it. With those strategies in mind, here are some potential arguments you could argue for or against!
- Jordan and Daisy, because they are generally disempowered, both use their sexuality in different ways to gain power, with different results.
- Despite Jordan’s overt cheating and lying, Daisy is, in fact, the more morally compromised person.
- The way Nick treats Jordan versus the way he describes Daisy reveals the novel’s preoccupation with Gatsby above all, to the detriment of the female characters.
Dear Diary: Today I cheated at golf yet again! But it was nothing compared to what my friend Daisy did...
Daisy Buchanan and Myrtle Wilson
While Daisy Buchanan and Myrtle Wilson obviously come from very different backgrounds and have conflicting motivations, they also have some surprising similarities.
Physical Appearance. Daisy and Myrtle both derive power from their looks. Myrtle's comfort with her voluptuous body is clearly appealing to Tom, while Daisy's magnetic voice and ethereal presence obsess Gatsby. Throughout the novel, Myrtle is frequently reduced to being just a body - one to be used or violated by those around her. Tom sees little in Myrtle besides someone to either rub up against, have sex with, or punch at will; George resorts to imprisoning Myrtle while she eggs him on to "beat" her (7.314) the way Tom does; and finally, Daisy gruesomely rips Myrtle's body apart with a car. Meanwhile, Daisy's voice also serves to make her less of a person in her own right and more of an idealized, mythic figure from fairy tales. For Gatsby, Daisy's voice is appealing because it is "full of money" (7.105) - he is attracted to her not because of who she is, but because he sees her as a prize.
Social Standing. Myrtle puts on the airs that Daisy has been born and raised with. This allows Myrtle to wield considerable social power within her group, as seen by how her guests fawn on her at the Manhattan party she throws. Daisy, in contrast, never exerts such overt power over a group – rather, she seems to move with crowds, doing what it expected of her (for instance marrying Tom despite still loving Gatsby).
Love and Relationships. Daisy and Myrtle’s marriages are strikingly quite different. Daisy and Tom are able to stay together even through serial affairs and murder. They end up loyal co-conspirators, protected by their wealth. Meanwhile, Myrtle has nothing but disdain for George despite his evident love for her. Still, both women use affairs with other men as a way to escape. Daisy wants to get away from an increasingly unhappy marriage and try to recapture the spontaneity and possibility of her youth, while Myrtle loves the status that her affair with Tom grants her. However, both learn that they can’t escape forever through their affairs. Obviously, their biggest difference is that Daisy gets to walk away from the novel unscathed, while Myrtle gets killed.
Daisy and Myrtle Essay Ideas
Here are ways to write about these different women who face similar choices with dramatically opposite conclusions.
- Despite their similarities in action and motivation, Daisy is protected from any lasting harm by her wealth and old money status, while Myrtle is punished for the same behavior, revealing how the class system in America protects the wealthy.
- The novel refuses to give any inner life to women, and instead reduces them to their physical qualities no matter what social class they come from. Daisy and Myrtle's similar treatment by the narrator and by the men around them shows that gender trumps class when determining status.
- Daisy and Myrtle’s similarities reveal how hollow the progress of the women’s movement really was at that point in time. Despite the big gains the movement made in the early twentieth century, including winning the right to vote and pushing for more freedom in how they could dress and act, both of these women’s lives aren’t vastly improved. They’re both trapped in unhappy marriages, they both rely on their looks/charms/sexuality to get what they want, and neither of them has even a chance of pursuing a fulfilling life through a career.
The butterfly may be beautiful, but it's still trapped.
Now that you’ve gone over the novel’s most popular compare/contrast pairings, check out our analysis of the novel’s romantic pairings in our guide to love, desire, and relationships in The Great Gatsby.
Have an essay about a symbol or motif? Get started with our symbols overview and motifs overview.
Still a little hazy on some of the plot elements in Gatsby? Not to worry, we have you covered with our complete book summary!
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1. Overview and organizing themes
This entry could have been given the title Scientific Methods and gone on to fill volumes, or it could have been extremely short, consisting of a brief summary rejection of the idea that there is any such thing as a unique Scientific Method at all. Both unhappy prospects are due to the fact that scientific activity varies so much across disciplines, times, places, and scientists that any account which manages to unify it all will either consist of overwhelming descriptive detail, or trivial generalizations.
The choice of scope for the present entry is more optimistic, taking a cue from the recent movement in philosophy of science toward a greater attention to practice: to what scientists actually do. This “turn to practice” can be seen as the latest form of studies of methods in science, insofar as it represents an attempt at understanding scientific activity, but through accounts that are neither meant to be universal and unified, nor singular and narrowly descriptive. To some extent, different scientists at different times and places can be said to be using the same method even though, in practice, the details are different.
Whether the context in which methods are carried out will be at all relevant, or to what extent it will be so, will depend largely on what one takes the aims of science to be and what one’s own aims are. For most of the history of scientific methodology the assumption has been that the most important output of science is knowledge and so the aim of methodology should be to discover those methods by which scientific knowledge is generated.
Science was seen to embody the most successful form of reasoning (but which form?) to the most certain knowledge claims (but how certain?) on the basis of systematically collected evidence (but what counts as evidence and, in particular, should the evidence of the senses or rather of rational insight take precedence?) Section 2 surveys some of the history, pointing to two major themes. One theme is seeking the right balance between observation and reasoning (and the attendant forms of reasoning which employ them); the other is how certain scientific knowledge is or can be.
Section 3 turns to 20th century debates on scientific method. In the second half of the 20th century the epistemic privilege of science faced several challenges and many philosophers of science abandoned the reconstruction of the logic of scientific method. Views changed significantly regarding which functions of science ought to be captured and why. For some, the success of science was better identified with social or cultural features. Historical and sociological turns in the philosophy of science were made, with a demand that greater attention be paid to the non-epistemic aspects of science, such as sociological, institutional, material, and political factors. Even outside of those movements there was an increased specialization in the philosophy of science, with more and more focus on specific fields within science. The combined upshot was very few philosophers arguing any longer for a grand unified methodology of science. Sections 3 and 4 surveys the main positions on scientific method in 20th century philosophy of science, focusing on where they differ in their preference for confirmation or falsification or for waiving the idea of a special scientific method altogether.
In recent decades, attention has primarily been paid to scientific activities traditionally falling under the rubric of method, such as experimental design and general laboratory practice, the use of statistics, the construction and use of models and diagrams, interdisciplinary collaboration, and science communication. Sections 4–6 attempt to construct a map of the current domains of the study of methods in science.
As these sections illustrate, the question of method is still central to the discourse about science. Scientific method remains a topic for education, for science policy, and among scientists. It arises in the public domain where the demarcation of science is at issue. Some philosophers have recently returned, therefore, to the question of what it is that makes science a unique cultural product. This entry will close with some of these recent attempts at discerning and encapsulating the activities by which scientific knowledge is achieved.
2. Historical Review: Aristotle to Mill
Attempting a history of scientific method compounds the vast scope of the topic. This section briefly surveys the background to modern methodological debates. What can be called the classical view goes back to antiquity, and represents a point of departure for later divergences.
We begin with a point made by Laudan (1968) in his historical survey of scientific method:
Perhaps the most serious inhibition to the emergence of the history of theories of scientific method as a respectable area of study has been the tendency to conflate it with the general history of epistemology, thereby assuming that the narrative categories and classificatory pigeon-holes applied to the latter are also basic to the former. (1968: 5)
To see knowledge about the natural world as falling under knowledge more generally is an understandable conflation. Histories of theories of method would naturally employ the same narrative categories and classificatory pigeon holes. An important theme of the history of epistemology, for example, is the unification of knowledge, a theme reflected in the question of the unification of method in science. Those who have identified differences in kinds of knowledge have often likewise identified different methods for achieving that kind of knowledge (see the entry on the unity of science).
Related to the diversities of what is known, and how, are differences over what can be known. Plato (429–347 B.C.E) distinguished the realms of things into the visible and the intelligible. Only the latter, the Forms, could be objects of knowledge. The intelligible truths could be known with the certainty of geometry and deductive reasoning. What could be observed of the material world, however, was by definition imperfect and deceptive, not ideal. The Platonic way of knowledge therefore emphasized reasoning as a method, downplaying the importance of observation. Aristotle (384–322 B.C.E) disagreed, locating the Forms in the natural world as the fundamental principles to be discovered through the inquiry into nature.
Aristotle is recognized as giving the earliest systematic treatise on the nature of scientific inquiry in the western tradition, one which embraced observation and reasoning about the natural world. In the Prior and Posterior Analytics, Aristotle reflects first on the aims and then the methods of inquiry into nature. A number of features can be found which are still considered by most to be essential to science. For Aristotle, empiricism, careful observation (but passive observation, not controlled experiment), is the starting point, though the aim is not merely recording of facts. Science (epistêmê), for Aristotle, is a body of properly arranged knowledge or learning—the empirical facts, but also their ordering and display are of crucial importance. The aims of discovery, ordering, and display of facts partly determine the methods required of successful scientific inquiry. Also determinant is the nature of the knowledge being sought, and the explanatory causes proper to that kind of knowledge (see the discussion of the four causes in the entry on Aristotle on causality).
In addition to careful observation, then, scientific method requires a logic as a system of reasoning for properly arranging, but also inferring beyond, what is known by observation. Methods of reasoning may include induction, prediction, or analogy, among others. Aristotle’s system (along with his catalogue of fallacious reasoning) was collected under the title the Organon. This title would be echoed in later works on scientific reasoning, such as Novum Organon by Francis Bacon, and Novum Organon Restorum by William Whewell (see below). In the Organon reasoning is divided primarily into two forms, a rough division which persists into modern times. The division, known most commonly today as deductive versus inductive method, appears in other eras and methodologies as analysis/synthesis, non-ampliative/ampliative, or even confirmation/verification. The basic idea is that there are two “directions” to proceed in our methods of inquiry: one away from what is observed, to the more fundamental, general, and encompassing principles; the other, leads from the fundamental and general to other possible specific instantiations of those principles.
The basic aim and method of inquiry identified here can be seen as a theme running throughout the next two millennia of reflection on the correct way to seek after knowledge: carefully observe nature and then seek rules or principles which explain or predict its operation. The Aristotelian corpus provided the framework for a commentary tradition on scientific method independent of the science itself (its physics and cosmos.) During the medieval period, figures such as Albertus Magnus (1206–1280), Thomas Aquinas (1225–1274), Robert Grosseteste (1175–1253), Roger Bacon (1214/1220–1292), William of Ockham (1287–1347), Andreas Vesalius (1514–1546), Giacomo Zabarella (1533–1589) all worked to clarify the kind of knowledge which could be obtained by observation and induction, the source of justification of induction, and the best rules for its application. Many of their contributions we now think of as essential to science (see also Laudan 1968). As Aristotle and Plato had employed a framework of reasoning either “to the forms” or “away from the forms”, medieval thinkers employed directions away from the phenomena or back to the phenomena. In analysis, a phenomena was examined to discover its basic explanatory principles; in synthesis, explanations of a phenomena were constructed from first principles.
During the Scientific Revolution these various strands of argument, experiment, and reason were forged into a dominant epistemic authority. The 16th–18th centuries were a period of not only dramatic advance in knowledge about the operation of the natural world—advances in mechanical, medical, biological, political, economic explanations—but also of self-awareness of the revolutionary changes taking place, and intense reflection on the source and legitimation of the method by which the advances were made. The struggle to establish the new authority included methodological moves. The Book of Nature, according to the metaphor of Galileo Galilei (1564–1642) or Francis Bacon (1561–1626), was written in the language of mathematics, of geometry and number. This motivated an emphasis on mathematical description and mechanical explanation as important aspects of scientific method. Through figures such as Henry More and Ralph Cudworth, a neo-Platonic emphasis on the importance of metaphysical reflection on nature behind appearances, particularly regarding the spiritual as a complement to the purely mechanical, remained an important methodological thread of the Scientific Revolution (see the entries on Cambridge platonists; Boyle; Henry More; Galileo).
In Novum Organum (1620), Bacon was critical of the Aristotelian method for proceeding too quickly and leaping from particulars to universals, largely as dictated by the syllogistic form of reasoning which regularly mixed those two types of propositions. Bacon aimed at the invention of new arts, of principles, of designations and directions for works. His method would be grounded in methodical collection of data and observations, coupled with correction of our senses (and particularly, strictures for the avoidance of the Idols, as he called them, kinds of systematic errors to which naïve observers are prone.) The community of scientists could then climb, by a careful, gradual and unbroken ascent, to reliable general claims.
Bacon’s method has been criticized as impractical and too inflexible for any living, practicing scientist. Whewell would later criticize Bacon in his System of Logic for paying too little attention to the practices of scientists. It is hard to find convincing examples of Bacon’s method being put in to practice in the history of science, but there are a few who have been held up as real examples of 16th century scientific, inductive method, even if not in the rigid Baconian mold: figures such as Robert Boyle (1627–1691) and William Harvey (1578–1657) (see the entry on Bacon).
It is to Isaac Newton (1642–1727), however, that historians of science and methodologists have paid the greatest attention, by far. Given the enormous success of his Principia Mathematica and Opticks, this is understandable. The study of Newton’s method has had two main thrusts: the implicit method of the experiments and reasoning presented in the Opticks, and the explicit methodological rules given as the Rules for Philosophising (the Regulae) in Book III of the Principia. Newton’s law of gravitation, the linchpin of his new cosmology, broke with explanatory conventions of natural philosophy, first for apparently proposing action at a distance, but more generally for not providing “true”, physical causes. The argument for his System of the World (Principia, Book III) was based on phenomena, not reasoned first principles. This was viewed (mainly on the continent) as insufficient for proper natural philosophy. The Regulae counter this objection, re-defining the aims of natural philosophy by re-defining the method natural philosophers should follow.
- Rule I: No more causes of natural things should be admitted than are both true and sufficient to explain their phenomena.
- Rule II: Therefore, the causes assigned to natural effects of the same kind must be, so far as possible, the same.
- Rule III: Those qualities of bodies that cannot be intended and remitted and that belong to all bodies on which experiments can be made should be taken as qualities of all bodies universally.
- Rule IV: In experimental philosophy, propositions gathered from phenomena by induction should be considered either exactly or very nearly true notwithstanding any contrary hypotheses, until yet other phenomena make such propositions either more exact or liable to exceptions.
To his list of methodological prescriptions should be added Newton’s famous phrase “hypotheses non fingo” (commonly translated as “I frame no hypotheses”.) The scientist was not to invent systems but infer explanations from observations, as Bacon had advocated. This would come to be known as inductivism. In the century after Newton, significant clarifications of the Newtonian method were made. Colin Maclaurin (1698–1746), for instance, reconstructed the essential structure of the method as having complementary analysis and synthesis phases, one proceeding away from the phenomena in generalization, the other from the general propositions to derive explanations of new phenomena. Denis Diderot (1713–1784) and editors of the Encyclopédie did much to consolidate and popularize Newtonianism, as did Francesco Algarotti (1721–1764). The emphasis was often the same, as much on the character of the scientist as on their process, a character which is still commonly assumed. The scientist is humble in the face of nature, not beholden to dogma, obeys only his eyes, and follows the truth wherever it leads. It was certainly Voltaire (1694–1778) and du Chatelet (1706–1749) who were most influential in propagating the latter vision of the scientist and their craft, with Newton as hero. Scientific method became a revolutionary force of the Enlightenment. (See also the entries on Newton, Leibniz, Descartes, Boyle, Hume, enlightenment, as well as Shank 2008 for a historical overview.)
Not all 18th century reflections on scientific method were so celebratory. Famous also are George Berkeley’s (1685–1753) attack on the mathematics of the new science, as well as the over-emphasis of Newtonians on observation; and David Hume’s (1711–1776) undermining of the warrant offered for scientific claims by inductive justification (see the entries on: George Berkeley; David Hume; Hume’s Newtonianism and Anti-Newtonianism). Hume’s problem of induction motivated Immanuel Kant (1724–1804) to seek new foundations for empirical method, though as an epistemic reconstruction, not as any set of practical guidelines for scientists. Both Hume and Kant influenced the methodological reflections of the next century, such as the debate between Mill and Whewell over the certainty of inductive inferences in science.
The debate between John Stuart Mill (1806–1873) and William Whewell (1794–1866) has become the canonical methodological debate of the 19th century. Although often characterized as a debate between inductivism and hypothetico-deductivism, the role of the two methods on each side is actually more complex. On the hypothetico-deductive account, scientists work to come up with hypotheses from which true observational consequences can be deduced—hence, hypothetico-deductive. Because Whewell emphasizes both hypotheses and deduction in his account of method, he can be seen as a convenient foil to the inductivism of Mill. However, equally if not more important to Whewell’s portrayal of scientific method is what he calls the “fundamental antithesis”. Knowledge is a product of the objective (what we see in the world around us) and subjective (the contributions of our mind to how we perceive and understand what we experience, which he called the Fundamental Ideas). Both elements are essential according to Whewell, and he was therefore critical of Kant for too much focus on the subjective, and John Locke (1632–1704) and Mill for too much focus on the senses. An interesting aspect of Whewell’s fundamental ideas is that they can be discipline relative. An idea can be fundamental even if it is necessary for knowledge only within a given scientific discipline (e.g., chemical affinity for chemistry). (This distinguishes fundamental ideas from the forms and categories of intuition of Kant. See Whewell entry.)
Clarifying fundamental ideas is therefore an essential part of scientific method and scientific progress. Whewell called this process “Discoverer’s Induction”. It was induction, following Bacon or Newton, but Whewell sought to revive Bacon’s account by emphasising the role of ideas in the clear and careful formulation of inductive hypotheses. Whewell’s induction is not merely the collecting of objective facts. The subjective plays a role through what Whewell calls the Colligation of Facts, a creative act of the scientist, the invention of a theory. A theory is then confirmed by testing, where more facts are brought under the theory, called the Consilience of Inductions. Whewell felt that this was the method by which the true laws of nature could be discovered: clarification of fundamental concepts, clever invention of explanations, and careful testing. Mill, in his critique of Whewell, and others who have cast Whewell as a fore-runner of the hypothetico-deductivist view, seem to have under-estimated the importance of this discovery phase in Whewell’s understanding of method (Snyder 1997a,b, 1999). Down-playing the discovery phase would come to characterize methodology of the early 20th century (see section 3).
Mill, in his System of Logic, puts forward instead a narrower view of induction as the essence of scientific method. For Mill, induction is the search first for regularities among events. Among those regularities, some will continue to hold for further observations, eventually gaining the status of laws. One can also look for regularities among the laws discovered in one domain, i.e., for a law of laws. Which “law law” will hold is time and discipline dependent and should be held open to revision. One example is the Law of Universal Causation, and Mill put forward specific methods for identifying causes—now commonly known as Mill’s methods. These five methods look for circumstances which are common among the phenomena of interest, those which are absent when the phenomena are, or those for which both vary together. Mill’s methods are still seen as capturing basic intuitions about experimental methods for finding the relevant explanatory factors (System of Logic (1843), see Mill entry). The methods advocated by Whewell and Mill, in the end, look similar. Both involve induction and generalization to covering laws. They differ dramatically, however, with respect to the necessity of the knowledge arrived at; that is, at the meta-methodological level (see the entries on Whewell and Mill entries).
3. Logic of method and critical responses
The quantum and relativistic revolutions in physics in the early 20th century had a profound effect on methodology. The conceptual foundations of both of these physical theories were taken to show the defeasibility of even the most seemingly secure commonsense intuitions about space, time and physical bodies. Certainty of knowledge about the natural world was therefore recognized as unattainable, and instead a renewed empiricism was sought, which rendered science fallible but at the same time rationally justified.
In support of this, analysis of the reasoning of scientists emerged according to which the aspects of scientific method which were of primary importance were the means of testing and confirming of theories. A distinction in methodology was made between the contexts of discovery and of justification. The distinction could be used as a wedge between, on the one hand the particularities of where and how theories or hypotheses are arrived at and, on the other, the underlying reasoning scientists use (whether or not they are aware of it) when assessing theories and judging their adequacy on the basis of the available evidence. By and large, for most of the 20th century, philosophy of science focused on the second context, although philosophers differed on whether to focus on confirmation or refutation as well as on the many details of how confirmation or refutation could or could not be brought about. By the mid-20th century these attempts at defining the method of justification and the context distinction itself came under pressure. During the same period, philosophy of science developed rapidly, and from section 4 this entry will therefore shift from a primarily historical treatment of the scientific method towards a primarily thematic one.
3.1 Logical constructionism and Operationalism
Advances in logic and probability held out promise of the possibility of elaborate reconstructions of scientific theories and empirical methods. The best example of this is Rudolf Carnap’s The Logical Structure of the World (1928) Here, Carnap attempted to show that a scientific theory could be understood as a formal axiomatic system—that is, a logic. Insofar as that system referred to the world, it did so because some of its basic sentences could be understood in terms of observations or operations which one could perform to test them. The rest of the theoretical system, including sentences using theoretical or unobservable terms (like electron or force) would then either be meaningful because they could be reduced to observations, or they had purely logical meanings (called analytic, like mathematical identities). This has been referred to as the verifiability criterion of meaning. According to the criterion, any statement not either analytic or verifiable was strictly meaningless. Although the view was endorsed by Carnap in 1928, he would later come to see it as too restrictive (Carnap 1956). Another familiar version of this idea is operationalism of Percy William Bridgman. In The Logic of Modern Physics (1927) Bridgman asserted that every physical concept could be defined in terms of the operations one would perform to verify the application of that concept. Making good on the operationalisation of a concept even as simple as length, however, can easily become enormously complex (for measuring very small lengths, for instance) or impractical (measuring large distances like light years.)
Carl Hempel’s (1950, 1951) criticisms of the verifiability criterion of meaning had enormous influence. He pointed out that universal generalizations, such as most scientific laws, were not strictly meaningful on the criterion. Verifiability and operationalism both seemed too restrictive to capture standard scientific aims and practice. And the tenuous connection between these reconstructions and actual scientific practice was criticized in another way. In both approaches, what are scientific methods are instead recast in methodological roles. Measurements, for example, were looked to as ways of giving meanings to terms. The aim of the philosopher of science was not to understand the methods per se, but to use them to reconstruct theories, their meanings, and their relation to the world. When scientists perform these operations, however, they will not report that they are doing them to give meaning to terms in a formal axiomatic system. This disconnect between methodology and the details of actual scientific practice would seem to violate the empiricism the Logical Positivists, or Bridgman, were committed to. The view that methodology should correspond to practice (to some extent) has been called historicism, or intuitionism. We turn to these criticisms and responses in section 3.4.
Positivism also had to contend with the recognition that a purely inductivist approach, along the lines of Bacon-Newton-Mill, was untenable. There was no pure observation, for starters. All observation was theory laden. Theory is required to make any observation, therefore not all theory can be derived from observation alone. (See also the entry on theory and observation in science). Even granting an observational basis, Hume had already pointed out that one could not argue for inductive conclusions without begging the question by presuming the success of the inductive method. Likewise, positivist attempts at analyzing how a generalization can be confirmed by observations of its instances were subject to a number of criticisms. In his riddle of induction, Goodman (1965) pointed out that for a set of observations, there will be multiple hypotheses that are equally supported. For example, the observation that all emeralds examined before today were green would support equally the two generalization ‘all emeralds are green’ and ‘all emeralds are grue’ where ‘x is grue’ iff either x has been examined before today and is green or x has not been examined before today and is blue. Goodman suggested that one could distinguish between generalizations that were supported by their instances and those that were not by comparing the entrenchment of their predicates—that is, the degree to which they have formed part of generalizations that have successfully been projected to account for new instances. In this way ‘all emeralds are green’ could be distinguished as more entrenched than ‘all emeralds are grue’. In the ‘Raven Paradox’, Hempel (1965) pointed out that if an observation confirms a given hypothesis, it also confirms all other hypotheses that are logically equivalent to it. For example, the generalization ‘all ravens are black’ is logically equivalent to the generalization ‘all non-black objects are non-ravens’, and the observation of a black raven, a red herring and a white shoe would therefore all confirm the hypothesis that ravens are black. Many find this paradoxical, but Hempel maintained that our intuition is based on a tacit appeal to background knowledge on the prevalence of ravens and non-ravens that prompt us to give more weight to evidence of ravens being black than to evidence of non-black items being non-ravens. (for more on these points of criticism as well as how they have been met, see the entries on confirmation and the problem of induction). We shall return to more recent attempts at explaining how observations can serve to confirm a scientific theory in section 4 below.
3.2. H-D as a logic of confirmation
The standard starting point for a non-inductive analysis of the logic of confirmation is known as the Hypothetico-Deductive (H-D) method. In its simplest form, the idea is that a theory, or more specifically a sentence of that theory which expresses some hypothesis, is confirmed by its true consequences. As noted in section 2, this method had been advanced by Whewell in the 19th century, as well as Nicod (1924) and others in the 20th century. Often, Hempel’s (1966) description of the H-D method illustrated by the case of Semmelweiss’ inferential procedures in establishing the cause of childbed fever has been presented as a key account of H-D as well as a foil for criticism of the H-D account of confirmation (see, for example, Lipton’s (2004) discussion of inference to the best explanation; also the entry on confirmation). Hempel described Semmelsweiss’ procedure as examining various hypotheses that would answer the question about the cause of childbed fever. Some hypotheses conflicted with observable facts and could be rejected as false immediately. Others needed to be tested experimentally by deducing which observable events should follow if the hypothesis were true (what Hempel called the test implications of the hypothesis), then conducting an experiment and observing whether or not the test implications occurred. If the experiment showed the test implication to be false, the hypothesis could be rejected. On the other hand, if the experiment showed the test implications to be true, this did not prove the hypothesis true. Although the confirmation of a test implication does not verify a hypothesis, Hempel did alow that “it provides at least some support, some corroboration or confirmation for it” (Hempel 1966: 8). The degree of this support then depends on the quantity, variety and precision of the supporting evidence.
3.3. Popper and falsificationism
Another approach that took off from the difficulties with inductive inference was Karl Popper’s critical rationalism or falsificationism (Popper 1959, 1963). Falsification is deductive and similar to H-D in that it involves scientists deducing observational consequences from the hypothesis under test. For Popper, however, the important point was not whatever confirmation successful prediction offered to the hypotheses but rather the logical asymmetry between such confirmations, which require an inductive inference, versus falsification, which can be based on a deductive inference. This simple opposition was later questioned, by Lakatos, among others. (See the entry on historicist theories of scientific rationality.)
Popper stressed that, regardless of the amount of confirming evidence, we can never be certain that a hypothesis is true without committing the fallacy of affirming the consequent. Instead, Popper introduced the notion of corroboration as a measure for how well a theory or hypothesis has survived previous testing—but without implying that this is also a measure for the probability that it is true.
Popper was also motivated by his doubts about the scientific status of theories like the Marxist theory of history or psycho-analysis, and so wanted to draw a line of demarcation between science and pseudo-science. Popper saw this as an importantly different distinction than demarcating science from metaphysics. The latter demarcation was the primary concern of many logical empiricists. Popper used the idea of falsification to draw a line instead between pseudo and proper science. Science was science because it subjected its theories to rigorous tests which offered a high probability of failing and thus refuting the theory. The aim was not, in this way, to verify a theory. This could be done all too easily, even in cases where observations were at first inconsistent with the deduced consequences of the theory, for example by introducing auxiliary hypotheses designed explicitly to save the theory, so-called ad hoc modifications. This was what he saw done in pseudo-science where the theories appeared to be able to explain anything that happened within the field to which they applied. In contrast, science is risky; if observations showed the predictions from a theory to be absent, the theory would be refuted. Hence, scientific hypotheses must be falsifiable. Not only must there exist some possible observation statement which could falsify the hypothesis or theory, were it observed, (Popper called these the hypothesis’ potential falsifiers) it is crucial to the Popperian scientific method that such falsifications be sincerely attempted on a regular basis.
The more potential falsifiers of a hypothesis, the more falsifiable it would be, and the more the hypothesis claimed. Conversely, hypotheses without falsifiers claimed very little or nothing at all. Originally, Popper thought that this meant the introduction of ad hoc hypotheses only to save a theory should not be countenanced as good scientific method. These would undermine the falsifiabililty of a theory. However, Popper later came to recognize that the introduction of modifications (immunizations, he called them) was often an important part of scientific development. Responding to surprising or apparently falsifying observations often generated important new scientific insights. Popper’s own example was the observed motion of Uranus which originally did not agree with Newtonian predictions, but the ad hoc hypothesis of an outer planet explained the disagreement and led to further falsifiable predictions. Popper sought to reconcile the view by blurring the distinction between falsifiable and not falsifiable, and speaking instead of degrees of testability (Popper 1985: 41f.).
3.4 Meta-methodology and the end of method
From the 1960s on, sustained meta-methodological criticism emerged that drove the philosophical focus away from scientific method. Something brief about those criticisms must be said here, but recommendations for further reading can be found at the end of the entry.
Thomas Kuhn’s The Structure of Scientific Revolutions (1962) begins with a well-known shot across the bow for philosophers of science:
History, if viewed as a repository for more than anecdote or chronology, could produce a decisive transformation in the image of science by which we are now possessed. (1962: 1)
The kind of image Kuhn wanted to transform was the a-historical, rational reconstruction sought by many of the Logical Positivists, though Carnap and other positivists were actually quite sympathetic to Kuhn’s views. (See the entry on the Vienna Circle). Kuhn shares with other of his contemporaries, such as Feyerabend and Lakatos, a commitment to a more empirical approach to philosophy of science. Namely, the history of science provides important data, and necessary checks, for philosophy of science, including any theory of scientific method.
An examination of the history of science reveals, according to Kuhn, that scientific development occurs in alternating phases. During normal science, the members of the scientific community adhere to the paradigm in place. Their commitment to the paradigm means a commitment to the puzzles to be solved and the acceptable ways of solving them. Confidence in the paradigm remains so long as steady progress is made in solving the shared puzzles. Method in this normal phase operates within a disciplinary matrix (Kuhn’s later concept of a paradigm) which includes standards for problem solving, as well as defines the range of problems the method should be applied to. An important part of a disciplinary matrix is the set of values which provide the norms and aims for scientific method. The main values that Kuhn identifies are prediction, problem solving, simplicity, consistency, and plausibility.
An important by-product of normal science, however, is the accumulation of puzzles which cannot be solved utilizing the resources of the current paradigm. Once the accumulation of these anomalies has reached some critical mass, it can trigger a communal shift to a new paradigm and a new phase of normal science. Importantly, the values that provide the norms and aims for scientific method may have transformed in the meantime. Method may therefore be relative to discipline, time or place
Feyerabend also identified the aims of science as progress, but argued that any methodological prescription would only stifle that progress (Feyerabend 1988). His arguments are grounded in re-examining accepted “myths” about the history of science. Heroes of science, like Galileo, are shown to be just as reliant on rhetoric and persuasion as they are on reason and demonstration. Others, like Aristotle, are shown to be far more reasonable and far-reaching in their outlooks then they are given credit for. As a consequence, the only rule that could provide what he took to be sufficient freedom was the vacuous “anything goes”. More generally, even the methodological restriction that science is the best way to pursue knowledge, and to increase knowledge, is too restrictive. Feyerabend suggested instead that science might, in fact, be a threat to a free society, because it and its myth had become so dominant (Feyerabend 1978).
An even more fundamental kind of criticism was offered by several sociologists of science from the 1970s onwards who dismissed what they saw as a false distinction between philosophical accounts of the rational development of science and sociological accounts of the irrational mistakes. Instead, they adhered to a symmetry thesis on which any causal explanation of how scientific knowledge is established needs to be symmetrical in explaining truth and falsity, rationality and irrationality, success and mistakes by the same causal factors (see, e.g., Barnes and Bloor 1982, Bloor 1991). Movements in the Sociology of Science, like the Strong Programme, or in the social dimensions and causes of knowledge more generally led to extended and close examination of detailed case studies in contemporary science and its history. (See the entries on the social dimensions of scientific knowledge and social epistemology.) Well-known examinations by Latour and Woolgar (1979/1986), Knorr-Cetina (1981), Pickering (1984), Shapin and Schaffer (1985) seemed to bear out that it was social ideologies (on a macro-scale) or individual interactions and circumstances (on a micro-scale) which were the primary causal factors in determining which beliefs gained the status of scientific knowledge. As they saw it, in other words, explanatory appeals to scientific method were not empirically well grounded.
By the close of the 20th century the search by philosophers for the scientific method was flagging. Nola and Sankey (2000b) could introduce their volume on method by remarking that “For some, the whole idea of a theory of scientific method is yester-year’s debate …”.
4. Statistical methods for hypothesis testing
Despite the many difficulties that philosophers encountered in trying to providing a clear methodology of conformation (or refutation), still important progress has been made on understanding how observation can provide evidence for a given theory. Work in statistics has been crucial for understanding how theories can be tested empirically, and in recent decades a huge literature has developed that attempts to recast confirmation in Bayesian terms. Here these developments can be covered only briefly, and we refer to the entry on confirmation for further details and references.
Statistics has come to play an increasingly important role in the methodology of the experimental sciences from the 19th century onwards. At that time, statistics and probability theory took on a methodological role as an analysis of inductive inference, and attempts to ground the rationality of induction in the axioms of probability theory have continued throughout the 20th century and in to the present. Developments in the theory of statistics itself, meanwhile, have had a direct and immense influence on the experimental method, including methods for measuring the uncertainty of observations such as the Method of Least Squares developed by Legendre and Gauss in the early 19th century, criteria for the rejection of outliers proposed by Peirce by the mid-19th century, and the significance tests developed by Gosset (a.k.a. “Student”), Fisher, Neyman & Pearson and others in the 1920s and 1930s (see, e.g., Swijtink 1987 for a brief historical overview; and also the entry on C.S. Peirce).
These developments within statistics then in turn led to a reflective discussion among both statisticians and philosophers of science on how to perceive the process of hypothesis testing: whether it was a rigorous statistical inference that could provide a numerical expression of the degree of confidence in the tested hypothesis, or if it should be seen as a decision between different courses of actions that also involved a value component. This led to a major controversy among Fisher on the one side and Neyman and Pearson on the other (see especially Fisher 1955, Neyman 1956 and Pearson 1955, and for analyses of the controversy, e.g., Howie 2002, Marks 2000, Lenhard 2006). On Fisher’s view, hypothesis testing was a methodology for when to accept or reject a statistical hypothesis, namely that a hypothesis should be rejected by evidence if this evidence would be unlikely relative to other possible outcomes, given the hypothesis were true. In contrast, on Neyman and Pearson’s view, the consequence of error also had to play a role when deciding between hypotheses. Introducing the distinction between the error of rejecting a true hypothesis (type I error) and accepting a false hypothesis (type II error), they argued that it depends on the consequences of the error to decide whether it is more important to avoid rejecting a true hypothesis or accepting a false one. Hence, Fisher aimed for a theory of inductive inference that enabled a numerical expression of confidence in a hypothesis. To him, the important point was the search for truth, not utility. In contrast, the Neyman-Pearson approach provided a strategy of inductive behaviour for deciding between different courses of action. Here, the important point was not whether a hypothesis was true, but whether one should act as if it was.
Similar discussions are found in the philosophical literature. On the one side, Churchman (1948) and Rudner (1953) argued that because scientific hypotheses can never be completely verified, a complete analysis of the methods of scientific inference includes ethical judgments in which the scientists must decide whether the evidence is sufficiently strong or that the probability is sufficiently high to warrant the acceptance of the hypothesis, which again will depend on the importance of making a mistake in accepting or rejecting the hypothesis. Others, such as Jeffrey (1956) and Levi (1960) disagreed and instead defended a value-neutral view of science on which scientists should bracket their attitudes, preferences, temperament, and values when assessing the correctness of their inferences. For more details on this value-free ideal in the philosophy of science and its historical development, see Douglas (2009) and Howard (2003).
In recent decades, philosophical discussions of the evaluation of probabilistic hypotheses by statistical inference have largely focused on Bayesianism that understands probability as a measure of a person’s degree of belief in an event, given the available information, and frequentism that instead understands probability as a long-run frequency of a repeatable event. Hence, for Bayesians probabilities refer to a state of knowledge, whereas for frequentists probabilities refer to frequencies of events (see, e.g., Sober 2008, chapter 1 for a detailed introduction to Bayesianism and frequentism as well as to likelihoodism). Bayesianism aims at providing a quantifiable, algorithmic representation of belief revision, where belief revision is a function of prior beliefs (i.e., background knowledge) and incoming evidence. Bayesianism employs a rule based on Bayes’ theorem, a theorem of the probability calculus which relates conditional probabilities. The probability that a particular hypothesis is true is interpreted as a degree of belief, or credence, of the scientist. There will also be a probability and a degree of belief that a hypothesis will be true conditional on a piece of evidence (an observation, say) being true. Bayesianism proscribes that it is rational for the scientist to update their belief in the hypothesis to that conditional probability should it turn out that the evidence is, in fact, observed. Originating in the work of Neyman and Person, frequentism aims at providing the tools for reducing long-run error rates, such as the error-statistical approach developed by Mayo (1996) that focuses on how experimenters can avoid both type I and type II errors by building up a repertoire of procedures that detect errors if and only if they are present. Both Bayesianism and frequentism have developed over time, they are interpreted in different ways by its various proponents, and their relations to previous criticism to attempts at defining scientific method are seen differently by proponents and critics. The literature, surveys, reviews and criticism in this area are vast and the reader is referred to the entries on Bayesian epistemology and confirmation.
5. Method in Practice
Attention to scientific practice, as we have seen, is not itself new. However, the turn to practice in the philosophy of science of late can be seen as a correction to the pessimism with respect to method in philosophy of science in later parts of the 20th century, and as an attempted reconciliation between sociological and rationalist explanations of scientific knowledge. Much of this work sees method as detailed and context specific problem-solving procedures, and methodological analyses to be at the same time descriptive, critical and advisory (see Nickles 1987 for an exposition of this view). The following section contains a survey of some of the practice focuses. In this section we turn fully to topics rather than chronology.
5.1 Creative and exploratory practices
A problem with the distinction between the contexts of discovery and justification that figured so prominently in philosophy of science in the first half of the 20th century (see section 2) is that no such distinction can be clearly seen in scientific activity (see Arabatzis 2006). Thus, in recent decades, it has been recognized that study of conceptual innovation and change should not be confined to psychology and sociology of science, but are also important aspects of scientific practice which philosophy of science should address (see also the entry on scientific discovery). Looking for the practices that drive conceptual innovation has led philosophers to examine both the reasoning practices of scientists and the wide realm of experimental practices that are not directed narrowly at testing hypotheses, that is, exploratory experimentation.
Examining the reasoning practices of historical and contemporary scientists, Nersessian (2008) has argued that new scientific concepts are constructed as solutions to specific problems by systematic reasoning, and that of analogy, visual representation and thought-experimentation are among the important reasoning practices employed. These ubiquitous forms of reasoning are reliable—but also fallible—methods of conceptual development and change. On her account, model-based reasoning consists of cycles of construction, simulation, evaluation and adaption of models that serve as interim interpretations of the target problem to be solved. Often, this process will lead to modifications or extensions, and a new cycle of simulation and evaluation. However, Nersessian also emphasizes that
creative model-based reasoning cannot be applied as a simple recipe, is not always productive of solutions, and even its most exemplary usages can lead to incorrect solutions. (Nersessian 2008: 11)
Thus, while on the one hand she agrees with many previous philosophers that there is no logic of discovery, discoveries can derive from reasoned processes, such that a large and integral part of scientific practice is
the creation of concepts through which to comprehend, structure, and communicate about physical phenomena …. (Nersessian 1987: 11)
Similarly, work on heuristics for discovery and theory construction by scholars such as Darden (1991) and Bechtel & Richardson (1993) present science as problem solving and investigate scientific problem solving as a special case of problem-solving in general. Drawing largely on cases from the biological sciences, much of their focus has been on reasoning strategies for the generation, evaluation, and revision of mechanistic explanations of complex systems.
Addressing another aspect of the context distinction, namely the traditional view that the primary role of experiments is to test theoretical hypotheses according to the H-D model, other philosophers of science have argued for additional roles that experiments can play. The notion of exploratory experimentation was introduced to describe experiments driven by the desire to obtain empirical regularities and to develop concepts and classifications in which these regularities can be described (Steinle 1997, 2002; Burian 1997; Waters 2007)). However the difference between theory driven experimentation and exploratory experimentation should not be seen as a sharp distinction. Theory driven experiments are not always directed at testing hypothesis, but may also be directed at various kinds of fact-gathering, such as determining numerical parameters. Vice versa, exploratory experiments are usually informed by theory in various ways and are therefore not theory-free. Instead, in exploratory experiments phenomena are investigated without first limiting the possible outcomes of the experiment on the basis of extant theory about the phenomena.
In recent years, the development of high throughput instrumentation in molecular biology and neighbouring fields has given rise to a special type of exploratory experimentation that collects and analyses very large amounts of data, and these new ‘omics’ disciplines are often said to represent a break with the ideal of hypothesis-driven science (Burian 2007; Elliott 2007; Waters 2007; O’Malley 2007) and instead described as data-driven research (Leonelli 2012; Strasser 2012) or as a special kind of “convenience experimentation” in which many experiments are done simply because they are extraordinarily convenient to perform (Krohs 2012).
5.2 Computer methods and the ‘third way’ of doing science
The field of omics just described is possible because of the ability of computers to process, in a reasonable amount of time, the huge quantities of data required. Computers allow for more elaborate experimentation (higher speed, better filtering, more variables, sophisticated coordination and control), but also, through modelling and simulations, might constitute a form of experimentation themselves. Here, too, we can pose a version of the general question of method versus practice: does the practice of using computers fundamentally change scientific method, or merely provide a more efficient means of implementing standard methods?
Because computers can be used to automate measurements, quantifications, calculations, and statistical analyses where, for practical reasons, these operations cannot be otherwise carried out, many of the steps involved in reaching a conclusion on the basis of an experiment are now made inside a “black box”, without the direct involvement or awareness of a human. This has epistemological implications, regarding what we can know, and how we can know it. To have confidence in the results, computer methods are therefore subjected to tests of verification and validation.
The distinction between verification and validation is easiest to characterize in the case of computer simulations. In a typical computer simulation scenario computers are used to numerically integrate differential equations for which no analytic solution is available. The equations are part of the model the scientist uses to represent a phenomenon or system under investigation. Verifying a computer simulation means checking that the equations of the model are being correctly approximated. Validating a simulation means checking that the equations of the model are adequate for the inferences one wants to make on the basis of that model.
A number of issues related to computer simulations have been raised. The identification of validity and verification as the testing methods has been criticized. Oreskes et al. (1994) raise concerns that “validiation”, because it suggests deductive inference, might lead to over-confidence in the results of simulations. The distinction itself is probably too clean, since actual practice in the testing of simulations mixes and moves back and forth between the two (Weissart 1997; Parker 2008a; Winsberg 2010). Computer simulations do seem to have a non-inductive character, given that the principles by which they operate are built in by the programmers, and any results of the simulation follow from those in-built principles in such a way that those results could, in principle, be deduced from the program code and its inputs. The status of simulations as experiments has therefore been examined (Kaufmann and Smarr 1993; Humphreys 1995; Hughes 1999; Norton and Suppe 2001). This literature considers the epistemology of these experiments: what we can learn by simulation, and also the kinds of justifications which can be given in applying that knowledge to the “real” world. (Mayo 1996; Parker 2008b). As pointed out, part of the advantage of computer simulation derives from the fact that huge numbers of calculations can be carried out without requiring direct observation by the experimenter/simulator. At the same time, many of these calculations are approximations to the calculations which would be performed first-hand in an ideal situation. Both factors introduce uncertainties into the inferences drawn from what is observed in the simulation.
For many of the reasons described above, computer simulations do not seem to belong clearly to either the experimental or theoretical domain. Rather, they seem to crucially involve aspects of both. This has led some authors, such as Fox Keller (2003: 200) to argue that we ought to consider computer simulation a “qualtitatively different way of doing science”. The literature in general tends to follow Kaufmann and Smarr (1993) in referring to computer simulation as a “third way” for scientific methodology (theoretical reasoning and experimental practice are the first two ways.). It should also be noted that the debates around these issues have tended to focus on the form of computer simulation typical in the physical sciences, where models are based on dynamical equations. Other forms of simulation might not have the same problems, or have problems of their own (see the entry on computer simulations in science).
6. Discourse on scientific method
Despite philosophical disagreements, the idea of the scientific method still figures prominently in contemporary discourse on many different topics, both within science and in society at large. Often, reference to scientific method is used in ways that convey either the legend of a single, universal method characteristic of all science, or grants to a particular method or set of methods privilege as a special ‘gold standard’, often with reference to particular philosophers to vindicate the claims. Discourse on scientific method also typically arises when there is a need to distinguish between science and other activities, or for justifying the special status conveyed to science. In these areas, the philosophical attempts at identifying a set of methods characteristic for scientific endeavors are closely related to the philosophy of science’s classical problem of demarcation (see the entry on science and pseudo-science) and to the philosophical analysis of the social dimension of scientific knowledge and the role of science in democratic society.
6.1 “The scientific method” in science education and as seen by scientists
One of the settings in which the legend of a single, universal scientific method has been particularly strong is science education (see, e.g., Bauer 1992; McComas 1996; Wivagg & Allchin 2002). Often, ‘the scientific method’ is presented in textbooks and educational web pages as a fixed four or five step procedure starting from observations and description of a phenomenon and progressing over formulation of a hypothesis which explains the phenomenon, designing and conducting experiments to test the hypothesis, analyzing the results, and ending with drawing a conclusion. Such references to a universal scientific method can be found in educational material at all levels of science education (Blachowicz 2009), and numerous studies have shown that the idea of a general and universal scientific method often form part of both students’ and teachers’ conception of science (see, e.g., Aikenhead 1987; Osborne et al. 2003).
Although occasionally phrased with reference to the H-D method, important historical roots of the legend in science education of a single, universal scientific method are the American philosopher and psychologist Dewey’s account of inquiry in How We Think (1910) and the British mathematician Karl Pearson’s account of science in Grammar of Science (1892). On Dewey’s account, inquiry is divided into the five steps of
(i) a felt difficulty, (ii) its location and definition, (iii) suggestion of a possible solution, (iv) development by reasoning of the bearing of the suggestions, (v) further observation and experiment leading to its acceptance or rejection. (Dewey 1910: 72)
Similarly, on Pearson’s account, scientific investigations start with measurement of data and observation of their correction and sequence from which scientific laws can be discovered with the aid of creative imagination. These laws have to be subject to criticism, and their final acceptance will have equal validity for “all normally constituted minds”. Both Dewey’s and Pearson’s accounts should be seen as generalized abstractions of inquiry and not restricted to the realm of science—although both Dewey and Pearson referred to their respective accounts as ‘the scientific method’.
Occasionally, scientists make sweeping statements about a simple and distinct scientific method, as exemplified by Feynman’s simplified version of a conjectures and refutations method presented, for example, in the last of his 1964 Cornell Messenger lectures. However, just as often scientists have come to the same conclusion as recent philosophy of science that there is not any unique, easily described scientific method. For example, the physicist and Nobel Laureate Weinberg described in the paper “The Methods of Science … And Those By Which We Live” (1995) how
The fact that the standards of scientific success shift with time does not only make the philosophy of science difficult; it also raises problems for the public understanding of science. We do not have a fixed scientific method to rally around and defend. (1995: 8)
6.2 Privileged methods and ‘gold standards’
Reference to the scientific method has also often been used to argue for the scientific nature or special status of a particular activity. Philosophical positions that argue for a simple and unique scientific method as a criterion of demarcation, such as Popperian falsification, have often attracted practitioners who felt that they had a need to defend their domain of practice. For example, references to conjectures and refutation as the scientific method are abundant in much of the literature on complementary and alternative medicine (CAM)—alongside the competing position that CAM, as an alternative to conventional biomedicine, needs to develop its own methodology different from that of science.
Also within mainstream science, reference to the scientific method is used in arguments regarding the internal hierarchy of disciplines and domains. A frequently seen argument is that research based on the H-D method is superior to research based on induction from observations because in deductive inferences the conclusion follows necessarily from the premises. (See, e.g., Parascandola (1998) for an analysis of how this argument has been made to downgrade epidemiology compared to the laboratory sciences.) Similarly, based on an examination of the practices of major funding institutions such as the National Institutes of Health (NIH), the National Science Foundation (NSF) and the Biomedical Sciences Research Practices (BBSRC) in the UK, O’Malley et al. (2009) have argued that funding agencies seem to have a tendency to adhere to the view that the primary activity of science is to test hypotheses, while descriptive and exploratory research is seen as merely preparatory activities that are valuable only insofar as they fuel hypothesis-driven research.
In some areas of science, scholarly publications are structured in a way that may convey the impression of a neat and linear process of inquiry from stating a question, devising the methods by which to answer it, collecting the data, to drawing a conclusion from the analysis of data. For example, the codified format of publications in most biomedical journals known as the IMRAD format (Introduction, Method, Results, Analysis, Discussion) is explicitly described by the journal editors as “not an arbitrary publication format but rather a direct reflection of the process of scientific discovery” (see the so-called “Vancouver Recommendations”, ICMJE 2013: 11). However, scientific publications do not in general reflect the process by which the reported scientific results were produced. For example, under the provocative title “Is the scientific paper a fraud?”, Medawar argued that scientific papers generally misrepresent how the results have been produced (Medawar 1963/1996). Similar views have been advanced by philosophers, historians and sociologists of science (Gilbert 1976; Holmes 1987; Knorr-Cetina 1981; Schickore 2008; Suppe 1998) who have argued that scientists’ experimental practices are messy and often do not follow any recognizable pattern. Publications of research results, they argue, are retrospective reconstructions of these activities that often do not preserve the temporal order or the logic of these activities, but are instead often constructed in order to screen off potential criticism (see Schickore 2008 for a review of this work).
6.3 Scientific method in the court room
Philosophical positions on the scientific method have also made it into the court room, especially in the US where judges have drawn on philosophy of science in deciding when to confer special status to scientific expert testimony. A key case is Daubert vs Merrell Dow Pharmaceuticals (92-102, 509 U.S. 579, 1993). In this case, the Supreme Court argued in its 1993 ruling that trial judges must ensure that expert testimony is reliable, and that in doing this the court must look at the expert’s methodology to determine whether the proffered evidence is actually scientific knowledge. Further, referring to works of Popper and Hempel the court stated that
ordinarily, a key question to be answered in determining whether a theory or technique is scientific knowledge … is whether it can be (and has been) tested. (Justice Blackmun, Daubert v. Merrell Dow Pharmaceuticals; see Other Internet Resources for a link to the opinion)
But as argued by Haack (2005a,b, 2010) and by Foster & Hubner (1999), by equating the question of whether a piece of testimony is reliable with the question whether it is scientific as indicated by a special methodology, the court was producing an inconsistent mixture of Popper’s and Hempel’s philosophies, and this has later led to considerable confusion in subsequent case rulings that drew on the Daubert case (see Haack 2010 for a detailed exposition).
6.4 Deviating practices
The difficulties around identifying the methods of science are also reflected in the difficulties of identifying scientific misconduct in the form of improper application of the method or methods of science. One of the first and most influential attempts at defining misconduct in science was the US definition from 1989 that defined misconduct as
fabrication, falsification, plagiarism, or other practices that seriously deviate from those that are commonly accepted within the scientific community. (Code of Federal Regulations, part 50, subpart A., August 8, 1989, italics added)
However, the “other practices that seriously deviate” clause was heavily criticized because it could be used to suppress creative or novel science. For example, the National Academy of Science stated in their report Responsible Science (1992) that it
wishes to discourage the possibility that a misconduct complaint could be lodged against scientists based solely on their use of novel or unorthodox research methods. (NAS: 27)
This clause was therefore later removed from the definition. For an entry into the key philosophical literature on conduct in science, see Shamoo & Resnick (2009).
The question of the source of the success of science has been at the core of philosophy since the beginning of modern science. If viewed as a matter of epistemology more generally, scientific method is a part of the entire history of philosophy. Over that time, science and whatever methods its practioners may employ have changed dramatically. Today, many philosophers have taken up the banners of pluralism or of practice to focus on what are, in effect, fine-grained and contextually limited examinations of scientific method. Others hope to shift perspectives in order to provide a renewed general account of what characterizes the activity we call science.
One such perspective has been offered recently by Hoyningen-Huene (2008, 2013), who argues from the history of philosophy of science that after three lengthy phases of characterizing science by its method, we are now in a phase where the belief in the existence of a positive scientific method has eroded and what has been left to characterize science is only its fallibility. First was a phase from Plato and Aristotle up until the 17th century where the specificity of scientific knowledge was seen in its absolute certainty established by proof from evident axioms; next was a phase up to the mid-19th century in which the means to establish the certainty of scientific knowledge had been generalized to include inductive procedures as well. In the third phase, which lasted until the last decades of the 20th century, it was recognized that empirical knowledge was fallible, but it was still granted a special status due to its distinctive mode of production. But now in the fourth phase, according to Hoyningen-Huene, historical and philosophical studies have shown how “scientific methods with the characteristics as posited in the second and third phase do not exist” (2008: 168) and there is no longer any consensus among philosophers and historians of science about the nature of science. For Hoyningen-Huene, this is too negative a stance, and he therefore urges the question about the nature of science anew. His own answer to this question is that “scientific knowledge differs from other kinds of knowledge, especially everyday knowledge, primarily by being more systematic” (Hoyningen-Huene 2013: 14). Systematicity can have several different dimensions: among them are more systematic descriptions, explanations, predictions, defense of knowledge claims, epistemic connectedness, ideal of completeness, knowledge generation, representation of knowledge and critical discourse. Hence, what characterizes science is the greater care in excluding possible alternative explanations, the more detailed elaboration with respect to data on which predictions are based, the greater care in detecting and eliminating sources of error, the more articulate connections to other pieces of knowledge, etc. On this position, what characterizes science is not that the methods employed are unique to science, but that the methods are more carefully employed.
Another, similar approach has been offered by Haack (2003). She sets off, similar to Hoyningen-Huene, from a dissatisfaction with the recent clash between what she calls Old Deferentialism and New Cynicism. The Old Deferentialist position is that science progressed inductively by accumulating true theories confirmed by empirical evidence or deductively by testing conjectures against basic statements; while the New Cynics position is that science has no epistemic authority and no uniquely rational method and is merely just politics. Haack insists that contrary to the views of the New Cynics, there are objective epistemic standards, and there is something epistemologically special about science, even though the Old Deferentialists pictured this in a wrong way. Instead, she offers a new Critical Commonsensist account on which standards of good, strong, supportive evidence and well-conducted, honest, thorough and imaginative inquiry are not exclusive to the sciences, but the standards by which we judge all inquirers. In this sense, science does not differ in kind from other kinds of inquiry, but it may differ in the degree to which it requires broad and detailed background knowledge and a familiarity with a technical vocabulary that only specialists may possess.
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