During the earliest part of the twentieth century, there was a similar, although smaller-scale, debate within English biology. In the latter part of the nineteenth century, a group of biologists called the "Biometricians" had formulated a mathematical law that they thought described inheritance. They had no mechanism for how inheritance works, and their law did not lend itself to supplementation with such a mechanism. In 1900 the pioneering work done by Mendel in the mid-nineteenth century was rediscovered, and the science of genetics was launched. For about six years, though, the Biometricians and the Mendelians conducted an intense debate about which approach to understanding inheritance was superior. One of the issues at stake was what kind of theory of inheritance should be the goal. The Biometricians thought that a mathematically formulated law was the right goal, while William Bateson, in the Mendelian camp, argued that understanding the mechanism of inheritance was the goal. In the short term, the Mendelians won the battle. In time the two approaches were married; modern biology now has both the math and the mechanism. But during the battle there was considerable argument about what a good scientific theory should do (Provine 1971; MacKenzie 1981).
So although Kuhns claims about linguistic incommensurability were overstated, I agree with him that incommensurability of standards is a real and interesting problem.
Kuhn's discussion of incommensurability is the main reason why his view of science is often referred to as "relativist." Kuhns book is often considered one of the first major steps in a tradition of work in the second half of the twentieth century that embraced relativism about science and knowledge. Kuhn himself was shocked to be interpreted this way.
But what is relativism? This is a chaotic area of discussion. Roughly speaking, relativist views tend to hold that the truth or justification of a claim, or the applicability of a rule or standard, depends on one's situation or point of view. Such a claim might be made generally ("all truth is relative") or in a more restricted way, about art, morality, good manners, or some other particular domain. The "point of view" might be that of an individual, a society, or some other group.
If people differ about the facts or the proper standards in some domain, that itself does not imply that relativism is true for that domain; some of the people might just be wrong. It is also important that if someone holds that moral rightness or good reasoning "depends on context," that need not be a form of relativism, although it might be. This is because a single set of moral rules (or rules of reasoning) might have built into them some sensitivity to circumstances. A set of moral rules might say, "If you are in circumstances X, you should do Y." That is not relativism, even though not everyone might be in circumstances X.
In this discussion we are mostly concerned with relativism applied to standards. More specifically, we are concerned with standards governing reasoning, evidence, and the justification of beliefs. And the "point of view" here is that of the users of a paradigm.
Is Kuhn a relativist with regard to these matters? The answer is that it's complicated. Kuhn had a subtle view that is hard to categorize. There is no simple answer, and I doubt that everything Kuhn said on the topic can be fitted together consistently. The issue of relativism in Kuhn is also bound up with the question of how to understand scientific progress, something Kuhn struggled with in the final pages of his book.
As we have seen, Kuhn argued that different paradigms often carry with them different rules for assessing theories and different standards for good and bad scientific work. So far, this does not tell us whether Kuhn was a relativist about these standards. But Kuhn also argued that the paradigms we have in science now are not closer than earlier paradigms to an "ideal" or "perfect" paradigm. Science is not heading toward a final paradigm that is superior to all others. We cannot say that there is, in principle, an ideal paradigm that contains methodological principles that are entitled to govern all of science, even though we do not have this paradigm yet.
This seems to be taking us close to a relativist view about the standards that are not shared across paradigms. But Kuhn said some rather different things in the final, somewhat puzzling, pages of Structure. There he said that our present paradigms have more problemsolving power than earlier paradigms did. This claim was made when Kuhn confronted the question of how to understand progress in science.
Kuhn gave two very different kinds of explanation for the apparent large-scale progress we see in science, and these two explanations are intertwined with each other in complex ways. Kuhns first form of explanation was a kind of "eye of the beholder" explanation. Science will inevitably appear to exhibit progress because each field has one paradigm per time, the victors after each revolution will naturally view their victory as progressive, and science is insulated from outside criticism. Happy celebrations of progress on the part of the victors will not be met with any serious objection. This deflationary explanation of the appearance of progress is consistent with a relativist view of the changes between paradigms.
Kuhn also developed a second, very different account of the appearance of progress in science. This one seems to conflict with a relativist reading. Here Kuhn argued that science has a special kind of efficiency, and this efficiency results in a real form of progress across revolutions. The progress is measured in problemsolving power; the number and precision of solutions to problems in a scientific field tend to grow over time (1996, 170). It is hard to reconcile this claim with some of his discussions of incommensurability in earlier chapters. There he said that revolutions always involve losses as well as gains, and he also said that the standards that might be used to classify some problems as important and others as unimportant tend to change in revolutions. So we should be skeptical about whether the kind of measurement of problemsolving power that Kuhn envisages in the last pages of Structure is compatible with the rest of the book.
If our later paradigms have more overall problemsolving power than our earlier ones, then it seems that we are entitled to regard the later ones as superior. This takes us away from relativism. Clearly Kuhn's aim was to work out an intermediate or moderate position (1996, zo5-6). People will be arguing about this for a while to come.
So far I have been mostly discussing the comparison of different paradigms within science. What about the comparison of science with entirely different approaches to knowledge? Here Kuhn is sometimes read as a relativist, but this is straightforwardly a mistake. Kuhn thought that the overall structure of modern scientific investigation gives us a uniquely efficient way of studying the world. So if we want to compare scientific procedures of investigation with nonscientific ones, it is clear that Kuhn thought science was superior. He was not a relativist about this issue, and perhaps that is the most important issue.
That concludes my discussion of incommensurability and relativism. There is one more issue that is often grouped with the problem of incommensurability; this is the "theoryladenness of observation." Kuhn argued that we cannot think of observation as a neutral source of information for choosing between theories, because what people see is influenced by their paradigm. Kuhn and a number of others developed radical views about observation around the same time. This is an important topic, as it challenges empiricism in a fundamental way. It will be discussed in chapter io.
6.4 The X-Rated "Chapter X"
Kuhn's book starts out with his patient analysis of normal science. The middle chapters become more adventurous, and then the book climaxes with Chapter X. Here Kuhn puts forward his most radical claims. Not only do ideas, standards, and ways of seeing change when paradigms change; in some sense the world changes as well. Reality itself is paradigm-relative or paradigm-dependent. After a revolution, "scientists work in a different world" (1996, 135).
Philosophers and other commentators tend to split between two different attitudes toward this part of Kuhns work. One group thinks that Kuhn exposes the fact that any idea of a single, stable world persisting through our various attempts to conceptualize it is an idea dependent on a failed view of
science and outdated psychological theories. Kuhn, on this interpretation, shows that changing our view of science requires us to change our metaphysics too-our most basic views about reality and our relationship to it. Holding onto the idea of a single fixed world that science strives to describe is holding onto the last and most fundamental element of a conservative view of conceptual change.
That is one position. Others think that this whole side of Kuhns work is a mess. When paradigms change, ideas change. Standards change also, and maybe the way we experience the world changes as well. But that is very different from claiming that the world itself depends on paradigms. The way we see things changes, but the world itself does not change.
I am in the second camp; the X-rated Chapter X is the worst material in Kuhn's great book. It would have been better if he had left this chapter in a taxi, in one of those famous mistakes that authors are prone to.
I should say immediately that it is not always clear how radical Kuhn wants to be in this chapter. Sometimes it seems that all he is saying is that our ideas and experience change. Also, there are some entirely reasonable claims we can make about changes to the world that result from paradigm changes. As paradigms change, scientists change their behavior and their experimental practices as well as their ideas. So some bits of the world change, in ordinary ways. And scientific revolutions result in new technologies that have far-reaching effects on the world we live in.
These changes can be far-reaching, but they are still restricted by the causal powers of human action. We can change plants and animals by controlled breeding and genetic engineering. We can dam rivers and also pollute them. But our reach is not indefinite. Kuhn discussed some cases in Chapter X that make it clear that he did not have these kinds of ordinary causal influences in mind. He discussed cases where changes in ideas about stars, planets, and comets led to astronomers "living in a different world," for example (1996, 117).
Most generally, though, the problem with these dramatic discussions is that Kuhn seems to think that the belief that we all inhabit a single world, existing independently of paradigms, also commits us to a naive set of ideas about perception and belief. But this is just not so. We might decide that perception is radically affected by beliefs and expectations, while still holding that perception is something that connects us to a single real world that we all inhabit.
Did Kuhn really make a mistake of this kind? As I have been so tough on him in this section, I should present my best "smoking gun" quote on the issue. Kuhn says:
At the very least, as a result of discovering oxygen, Lavoisier saw nature differently. And in the absence of some recourse to that hypothetical fixed nature that he "saw differently," the principle of economy will urge us to say that after discovering oxygen Lavoisier worked in a different world. (1996, 118)
The passage is very strange. "Principle of economy"? Would it be economical for us to give up the idea that Lavoisier was living in the same world as the rest of us and acquiring new ideas about it? It is supposed to be economical to think that with every conceptual change of this kind, the scientist comes to live in a new, different world? Appeals to "economy" are often suspicious in the philosophy of science. They are usually weak arguments. This one also seems to have the accounting wrong.
From the point of view of a special kind of skeptical philosophical discussion, it can be considered "hypothetical" that there is a world beyond our momentary sensory experiences and ideas. But this is a very special sense of "hypothetical"! If we are trying to understand science as a social activity, as Kuhn is, there is nothing hypothetical about the idea that science takes place in a single, structured world that interacts with the community of scientists via the causal channels of perception and action.
The issues just discussed connect to another noteworthy feature of Kuhn's view of science. Kuhn opposed the idea that the large-scale history of science involves an accumulation of more and more knowledge about how the world really works. He was willing, on occasion, to recognize some kinds of accumulation of useful results as science moves along. There is an accumulation (maybe) of a kind of problemsolving power. But we cannot see, in science, an ongoing growth of knowledge about the structure of the world.
When Kuhn wrote about this issue, he often came back to cases in the history of physics. Like Popper and others, Kuhn seems to have been hugely influenced by the fall of the Newtonian picture of the world at the start of the twentieth century. Many philosophers of science seem to have been made permanently pessimistic about confirmation and the accumulation of factual knowledge by this episode. But Kuhn, and perhaps others, was surely too focused on the case of theoretical physics. He seems to have thought that we can only see science as achieving a growth of knowledge about the structure of the world if we can see this kind of progress in the parts of science that deal with the most low-level and fundamental entities and processes. But if we look at other parts of science-at chemistry and molecular biology, for example-it is much more reasonable to see a continuing growth (with some hiccups) in knowledge about how the world really works. We see a steady growth in knowledge about the structures of sugars, fats, proteins, and other important molecules, for example. There is no evidence that these kinds of results will come to be replaced, as opposed to extended, as science moves along. This type of work does not concern the most basic features of the universe, but it is undoubtedly science. It is possible that, when we try to work out how to describe the growth of knowledge over time in science, we should treat theoretical physics is a special case and not as a model for all science (McMullin 1984). So Kuhn's pessimism regarding the accumulation of knowledge about the structure of the world in science seems badly overstated.
6.5 Final Thoughts on Kuhn
Kuhn changed the philosophy of science by describing a tremendously vivid picture of scientific change. This picture was full of unexpected features, and Kuhn tried to shed light on traditional epistemological questions by looking at these questions from unusual angles. Most importantly, Kuhn attributed the success and the power of science to a delicate balance between factors in a complex and fragile mechanism. Science owes its strength to an interaction between the ordered cooperation and single-mindedness of normal science, together with the ability of these ordered behavioral patterns to break down and reconstitute themselves in revolutions. Periodic injections of disorder are just as essential to the process as the well-regulated behaviors found in normal science.
That is Kuhn's mechanism. Quite quickly, critics were able to find problems with this mechanism when interpreted as a description of how science actually works. I have already mentioned two important objections: single paradigms rarely have the kind of dominance that Kuhn describes, and large-scale changes can occur without crises. Many parts of Kuhns mechanism are especially hard to apply to the history of biology, which Kuhn did not much discuss. Kuhn's account of the mechanisms behind scientific change is in several ways too tightly structured, too specific. The real story is more mixed. But Kuhns was the first prominent attempt at a new kind of approach to the philosophy of science, a new kind of theory. These are theories that approach questions in the philosophy of science by looking at the social structure of science and the mechanisms underlying scientific change. This approach has flourished.
Back in the first chapter, I distinguished views that construe science broadly from those that construe it narrowly. Some philosophies of science are really extensions of more general theories in epistemology, psychology, or the philosophy of language. These views see the difference between science and everyday problemsolving as a matter of detail and degree. Kuhn's theory is nothing like this. His theory of science emphasizes the differences between science, narrowly construed, and various other kinds of empirical learning and problemsolving. Science is a form of organized behavior with a specific social structure, and science seems only to thrive in certain kinds of societies. As a consequence, science appears in this story as a rather fragile cultural achievement; subtle chan
ges in the education, incentive structure, and political situation of scientists could result in the loss of the special mechanisms of change that Kuhn described.
Before moving on, as a kind of brief appendix I will mention some interesting connections between Kuhn's theory of science and a few other famous mechanisms for change. First, in some ways Kuhns view of science has an "invisible hand" structure. The Scottish political and economic theorist Adam Smith argued in the Wealth of Nations (['776] 1976) that individual selfishness in economic behavior leads to good outcomes for society as a whole. The market is an efficient distributor of goods to everyone, even though the people involved are each just out for themselves. Here we have an apparent mismatch between individual-level characteristics and the characteristics of the whole; selfishness at one level leads to the general benefit. But the mismatch is only apparent; it disappears when we look at the consequences of having a large number of individuals interacting together. We see something similar in Kuhns theory of science: narrowmindedness and dogmatism at the level of the individual lead to intellectual openness at the level of science as a whole. Anomaly and crisis produce such stresses in the normal scientist that an especially wholesale openness to novelty is found in revolutions. In the next chapter we will look at one critic who was suspicious of Kuhn on exactly this point; he thought Kuhn was trying to excuse and encourage the most narrowminded and unimaginative trends in modern science.
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