Kuhn and Popper (Andrew Pickin) 1.The perceived difference in methods: normative versus descriptive

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1 Kuhn and Popper (Andrew Pickin) In the article Reflections on my Critics Kuhn sorts the points made by Popper, Feyerabend, Lakatos, Toulmin and Watkins into three categories. 1 Although the primary aim of this essay is to provide a comparison of the views of Kuhn and Popper it is not so much concerned with the legitimacy of the points made by Kuhn s critics, nor with the adequacy of Kuhn s replies it will be useful to structure the essay around the three categories. 1.The perceived difference in methods: normative versus descriptive Kuhn correctly observes that some of his critics see him as solely concerned with giving a description of science, whereas Popper s approach, they say, is normative. For example, Watkins writes: Popper says, in effect, that major theoretical advances in science ought to have a revolutionary character; and Kuhn says, in effect, that they do have a revolutionary character. 2 And Feyerabend is not sure what to make of Kuhn: Whenever I read Kuhn, I an troubled by the following question: are we here presented with methodological prescriptions which tell the scientist how to proceed; or are we given a description, void of any evaluative element, of those activities which are generally called scientific? Kuhn s writings, it seems to me, do not lead to a straightforward answer. They are ambiguous in the sense that they are compatible with, and lend support to, both interpretations. 3 Kuhn s reply is emphatic. In response to Feyerabend s queries he writes: 1 Kuhn (1969:233) 2 Watkins (1965:37) [Watkins s italics] 3 Feyerabend (1969:198) [Feyerabend s italics]

2 The answer, of course, is that they [i.e., Kuhn s remarks] should be read in both ways [i.e., as descriptions and as prescriptions] at once. If I have a theory of how and why science works, it must necessarily have implications for the way in which scientists should behave if their enterprise is to flourish scientists should behave essentially as they do if their concern is to improve scientific knowledge. 4 Thus, Kuhn s account is normative in the following sense: it attempts to tell us how scientists do behave; and how scientists do behave is essentially how they should behave. Popper is also concerned with the question of how scientists ought to behave. However, there is a significant difference between his view and Kuhn s although Kuhn plays it down. The difference is this: Kuhn thinks that science is largely successful, and further that this is necessarily so. The reason for this is that he does not think that there can be criteria of scientific success which are independent of our understanding of the essentials of the scientific process. 5 Thus, for Kuhn, description and prescription go hand in hand. For Popper, in contrast, they come apart. Popper thinks that the aim of science ought to be to get nearer to the truth. Science could therefore be largely unsuccessful; science that fails to get nearer to the truth is unsuccessful science. Thus, for Popper, the normative question of how scientists ought to behave is principally separate from the question of how in fact they do behave. From these considerations another difference between Kuhn and Popper emerges. We have already made the point that Kuhn approaches normative concerns through the project of description. Now, Kuhn thinks that a description of science must, in the final analysis, be psychological or sociological. 6 Consequently, Kuhn approaches the normative question through psychology and sociology. Popper s arguments, on the other hand, are essentially logical. He advocates for science the critical method on the grounds that the search for truth logically requires the elimination of falsehoods. 2. Normal science 4 Kuhn (1969:237) 5 Kuhn (1969:264) 6 Kuhn (1965:21)

3 The second category of criticisms identified by Kuhn groups together remarks made about what Kuhn labels normal science. Again, I will not survey the remarks, nor will I bother with a description of normal science. 7 Instead I will sketch some differences between the views of Kuhn of Popper in the area of normal science. I begin with two remarks: First, Popper agrees that normal science exists. 8 Second, contrary to Watkins s reading of Kuhn, Kuhn thinks that the central episodes in scientific advance are revolutions. 9 Now that the remarks are dealt with, let us turn to where Kuhn and Popper differ. Popper acknowledges that normal science exists, and then goes on to characterise it as a danger to science 10 ; later he characterises its practitioners as applied scientists rather than pure scientists. 11 Popper therefore thinks both that normal science ought to be avoided and that it is not proper science. Kuhn disagrees on both counts. Kuhn first argues that the existence of normal science is a logical corollary of the existence of revolutions. 12 However, since Popper accepts that normal science exists, there is no obvious disagreement here. The real conflict arises when Kuhn goes on to explain why he sees value in normal science. He thinks that once the transition to normal science is made, the time for steady criticism and theory proliferation has passed. 13 There are benefits to focusing all energy on a particular theory; Kuhn writes, Because they can ordinarily take current theory for granted, exploiting rather than criticizing it, the practitioners of mature sciences are freed to explore nature to an esoteric depth and detail otherwise unimaginable. 14 In contrast, Popper advocates the critical method for science at all times. It should be mentioned that Popper does think that there is a need for some dogmatism; theories must be retained long enough to extract their true worth. And Kuhn accepts that critical thinking has an important role to play in science. Thus, their disagreement over normal science is far from absolute. 7 I will write normal science for what Kuhn means by normal science. And I will write normal science for what is conventionally meant by normal science. 8 Normal science, in Kuhn s sense, exists Popper (1965:52) 9 Kuhn (1969:241) 10 Popper (1965:52) 11 Popper (1965:53) 12 Kuhn (1969); see p.233 and p Kuhn (1969:246) 14 Kuhn (1969:247)

4 As stated above, Popper does not think that normal science is science in the proper sense of the term. Popper demarcates science by the presence of the possibility of refutation by observation and experiment. It is not clear that Popper describes normal science as applied science because he thinks that it fails to meet his demarcation criterion. However, mentioning the demarcation criterion allows us to notice another divergence of the views of Popper and Kuhn. Although Kuhn does not believe that it is possible to find a sharp line of demarcation, 15 he does think that puzzle solving is more fundamental to science than testing (he does, however, think that the presence of testing is necessary for a field to qualify as a science 16 ). 3.Irrationality, Relativism, and Incommensurability The third category of criticisms picked out by Kuhn consists of charges of irrationality, relativism, and the defence of mob rule. As usual, I shall only consider how these criticisms relate to a comparison of Kuhn and Popper. Also, I will not discuss mob rule Irrationality Lakatos writes the following about Kuhn s view: Each paradigm contains its own standards. The crisis sweeps away not only the old theories and rules but also the standards which made us respect them. The new paradigm brings a totally new rationality. There are no super-paradigmatic standards. The change is a bandwagon effect. Thus in Kuhn s view scientific revolution is irrational. 17 The passage nicely captures the reason why Kuhn is accused of declaring science irrational. Lakatos s interpretation of Kuhn is wide of the mark. Kuhn thinks that there are many good reasons for choosing one theory rather than another, and he cites some: 15 Kuhn (1965:6) 16 Kuhn (1969:245) 17 Lakatos (1969:178) [Lakatos s italics]

5 accuracy, scope, simplicity, and fruitfulness. 18 These are Kuhn s super-paradigmatic standards. The standards enable him to make sense of rational scientific revolution. Thus, Kuhn and Popper agree that science is, and ought to be, rational. They do, however, differ in their conceptions of rationality. Popper thinks that the critical attitude is characteristic of the rational attitude. 19 On the other hand, we have already seen that Kuhn believes that science does not need to be critical at all times. 3.2 Relativism and Incommensurability Kuhn is also charged with relativism. In response, he writes, In one sense of the term I may be a relativist; in a more essential one I am not. 20 Looking at why Kuhn thinks that he is a relativist will bring out further divergence of his own views and Popper s. The reason why Kuhn thinks that he is in some sense a relativist pertains to truth. Namely, he rejects the idea that one theory can be a better approximation to the truth than another theory. This rejection marks a substantial clash between himself and Popper; it is a rejection Popper s criterion of verisimilitude, and this criterion is a fundamental feature of Popper s philosophy of science. I think that there are two motivations for Kuhn s rejection of the idea that one theory can be a better approximation to the truth than another theory. The first is that he does not believe that one theory can be a better representation of what is really out there than another. He writes: To say, for example, of a field theory that it approaches more closely to the truth than an older matter-and-force theory should mean, unless words are being oddly used, that the ultimate constituents of nature are more like fields than like matter and force. But in this ontological context it is far from clear how the phrase more like is to be applied. Comparison of historical theories gives no sense that their ontologies are approaching a limit: in some fundamental ways Einstein s general relativity resembles Aristotle s physics more than Newton s. In any case, the evidence from which conclusions about an ontological limit are 18 Kuhn (1969:261) 19 Popper (1979:31) 20 Kuhn (1969:264)

6 to be drawn is the comparison not of whole theories but of their empirical consequences. That is a major leap, particularly in the face of a theorem that any finite set of consequences of a given theory can be derived from another incompatible one. 21 The second motivation is related to his notion of incommensurability. Kuhn frequently says that successive theories are incommensurable. One sense in which successive theories are incommensurable, and the important one in this context, is that in the transition from one theory to the next words change their meanings or conditions of applicability in subtle ways. 22 There is no such thing as a theoryindependent vocabulary. Kuhn thinks that a theory-independent vocabulary is required for comparing the verisimilitude of alternate theories (it is not at all clear to me that this is right), and for this reason he sees a second reason to reject Popper s criterion of verisimilitude. Bibliography Feyerabend (1969): Consolations for the Specialist, in Lakatos and Musgrave (eds.): Criticism and the Growth of Knowledge, Kuhn (1965): Logic of Discovery or Psychology of Research?, in Lakatos and Musgrave (eds.): Criticism and the Growth of Knowledge, Kuhn (1969): Reflections on my Critics, in Lakatos and Musgrave (eds.): Criticism and the Growth of Knowledge, Lakatos (1969): Falsification and the Methodology of Scientific Research Programmes, in Lakatos and Musgrave (eds.): Criticism and the Growth of Knowledge, Popper (1965): Normal Science and its Dangers, in Lakatos and Musgrave (eds.): Criticism and the Growth of Knowledge, Popper (1979): Objective Knowledge: An Evolutionary Approach, OUP, Oxford. Watkins (1965): Against Normal Science, in Lakatos and Musgrave (eds.): Criticism and the Growth of Knowledge, Kuhn (1969:265) 22 Kuhn (1969:266)