An essay I wrote on relativism in Kuhn's theory of scientific revolutions.

Does Kuhn's portrayal of science involve an unacceptable relativism?

Thomas Kuhn developed a theory of science in his book The Structure of Scientific Revolutions. It has a hostile reception amongst philosophers, especially those who advocated an objective standard or framework for science. Philosophers like Popper and Lakatos attacked Kuhn for developing an unacceptable relativism the undermined their preferred conception of the discipline. Ultimately they are right insofar as they claim it is relativistic, but I don't think it constitutes an unacceptable relativism. Rather I sympathise with those who claim that his relativism did not go far enough.

Kuhn's central thesis is that science operates in a cycle of revolutions with three phases. In the first pre-scientific phase, scientists work with several incompatible and incomplete theories. Eventually one theory becomes accepted by enough scientists that it becomes dominant and so scientists begin to use it as their basic methodology. Kuhn called this dominant framework a paradigm, borrowing from the linguistic term meaning systematic arrangement of all the inflections of a term. Scientists then practice in the second phase, which Kuhn called normal science. In this phase, scientists engage in puzzle solving, trying to expand the paradigm. Inevitably, anomalies will arise that cannot be explained with any theory that would fit the dominant paradigm. They will generally be dismissed or put to one side, until they gain sufficient weight for a crisis of revolutionary science. During this phase the paradigm and its axioms can be re-examined, leading to a new paradigm that has all of the explanatory power of its predecessor in addition to the ability to explain some or all of the anomalies. The change to a new paradigm was called a paradigm shift.

The obvious consequence of this theory is that science has no permanent, objective methodological or semantic standards. It rejects standards like falsification and confirmation, and posits social context – the struggle for dominance in the scientific culture – as the ultimate arbiter of scientific knowledge and progress.

The first problem that this raises relates to a definition of science. How one can distinguish science from other intellectual enterprises, since there is nothing inherent in the methodology or meaning of the discipline? Kuhn might reply that science is simply that which studies the natural world, or even the discipline that can be defined by the methodology of revolutions, i.e. by reference to the phases of pre-theory, normal science and revolutionary science. Positivists like Popper would object to this, since it allows for fields like psychology and sociology to be counted as scientific.

In fact, many other enterprises could conceivably involve these phases, including philosophy itself. Kuhn later revised his theory to admit the possibility of normal and revolutionary science occurring in parallel, which in turn allows for a narrow interpretation of almost any intellectual enterprise as being scientific. If I settle upon one theoretical framework and try to solve philosophical problems within that perspective, am I not practicing normal science? And if I then reject that framework and develop a new one that exceeds its predecessor's explanatory power, am I not undergoing a paradigm shift?

It would seem that Kuhn can only resort to defining science by reference to its subject matter – the natural world – but that itself is problematic due to the incommensurability of terms, a consequence of Kuhn's theory.

According to Kuhn, we judge a theory by reference to a paradigmatic theory, rather than to some permanent, theory-independent rules (such as whether or not it is falsifiable). This has several important consequences. First, scientific theories and methodology are relative to their paradigm, there is nothing permanent about the discipline, as I have explored briefly already. Second, theories from different paradigms are incommensurable since they have no shared paradigmatic theory against which they can be judged. I cannot easily compare Newton's theory of gravity with Einstein's since the two theories can only be explained by reference to their paradigm. I am unable, in other words, to escape any given paradigm and compare two paradigmatically different theories. This is methodological incommensurability (Bird, 4.1).

Furthermore, scientists must suffer observational incommensurability. Observation, Kuhn suggested, is theory-dependent as it is influenced by prior beliefs based in the current paradigm; scientists in different paradigms will perceive the same event differently because of the theoretical framework through which they view the world (Bird, 4.2). So when a scientist in a pre-Newtonian paradigm sees an apply fall to the ground, he may observe an apple moving towards the ground. A scientist observing the same phenomena in a post-Newtonian paradigm will see an apple under the force of gravity changing its inertia. The two observations, Kuhn says, cannot be compared. So one cannot even rely on the evidence of previous paradigms, it must be reinterpreted. It may even have to be re observed, if one takes this form of incommensurability seriously, since we have no reason to believe the observation statements of scientists from different paradigms.

Finally, scientists must contend with semantic incommensurability. Fields of science, Kuhn said, are governed by taxonomies that divide its subject matter into kinds, with an associated lexical network (of terminology). Scientific revolutions involve a change in meaning of terminology, and since Kuhn thought that meaning was holistic this would involve a change in the whole lexical network and therefore also the taxonomy. So terminology and taxonomies cannot be translated between paradigms (Bird, 4.4).

A realist might then object that if scientific theories are potential descriptions of the world “involving reference to worldly entities, kind, and properties” (Bird, 6.2) then how can we take them to be incommensurable? The sense (the meaning) may change, but the reference cannot. They still refer to same concepts, even where the understanding is different (e.g. Newton and Einstein and their understanding of “mass”). To a realist, one understanding is simply closer to the truth and so the two different understandings are still commensurable, even if only in reference and not in meaning.

Kuhn might reply that with different conceptualisations of the world that describe the same phenomena, the references may be the same but the scientist cannot interpret or understand these independent of his subjective theoretical framework – i.e. depending upon the sense of the terminology. One cannot say that mass refers to the same thing for Newton and Einstein since one can only understand the term “mass” from one of their theoretical frameworks.

The realist would content that natural kind terms are sense-free, particularly causal theories of reference. For example, two theories that explain how gravity causes that apple to fall towards the earth are commensurable because they refer to kinds that are wholly objective as far as scientists are concerned (we have no scientists who can dispute terms like “apple” and “towards the earth”). Though the observations may be different insofar as they are embedded in a theoretical framework, the natural kind terms are objective. Similarly natural kind terms like “mass” and “acceleration” change in sense but not in reference (Bird, 6.2).

Kuhn might finally reply that this only shows that reference can be retained, not that it must be, so one can still defend an extremely relativistic conceptualisation of scientific revolutions as being possible if not necessary. In other words, there is nothing necessarily objective about science, and so if its objectivity is contingent then Kuhn can claim that his study of the history of science supports his theory of the structure of scientific revolutions.

Furthermore, for a philosopher or scientist to be aware of any such continuity one would need to posit some external guarantor of truth so that he one could observe the continuity within the current paradigm (i.e. independent of its standards of evaluation). This could either be what Kuhn termed an “Archimedean platform”, upon which the philosopher can compare two theories without any theoretical framework that might bias his analysis. Or it could be an epistemic standard such as reliability, according to which the philosopher could judge how science has improved or degenerated in between paradigms.

Kuhn's arguments seem convincing. For while it may be useful to think of science as being a cumulative discipline that adheres to strict, objective standards, the failure of Kuhn's adversaries to posit any convincing account of such a set of standards suggests that science is indeed more humanised than they want to think.

Paul Feyerabend took this point further to suggest that it is good that scientists aren't restricted by any particular methodological, observational or semantic framework, since such a framework would limit the activities of the scientist and hence restrict scientific progress. Although he took issue with Kuhn's strict delineation of normal and revolutionary science, he thought that scientists engaged in puzzle solving could not adhere to the truth. Rather, scientists ought to operate in a kind of methodological anarchism, so that they are free to pursue any line of thought they choose (Preston).

Strictly speaking Feyerabend rejects Kuhn's model of scientific revolutions outright, dismissing it as simplistic. In fact, he contends that philosophers have nothing useful to say about scientific methodology, and advised scientists to ignore philosophers. But as a defense against those who attack Kuhn's relativism, Feyerabend provides compelling arguments. He idealised Kuhn's descriptions of the pre-scientific and revolutionary phases of science, and claimed that all good science occurred during these phases. He therefore rejected outright the phases in which there is any continuity, and so denied not only incommensurability between paradigms but also between theories.

Even if one rejects Feyerabend's extreme incommensurability thesis, and even if one rejects Kuhn's particular structure of scientific revolutions, one can still preserve his theory of incommensurability between paradigms. His detractors have failed to develop a convincing account of how theories from different paradigms can be compared, and so I must conclude that Kuhn's portrayal of science doesn't involve an unacceptable relativism.

Bibliography

Alexander Bird, 2004, Thomas Kuhn, entry in the Standard Encyclopedia of Philosophy: http://www.seop.leeds.ac.uk/entries/kuhn, on file with author

W.H.Newton-Smith, 2001, A Companion to the Philosophy of Science, Orxord: Blackwel

John Preston, 2002, Paul Feyerabend, entry in the Standard Encyclopedia of Philosophy: http://www.seop.leeds.ac.uk/entries/feyerabend, on file with author