The Psychiatrist In Search of a Science

II. Developments in the Logic and the Sociology of Science

¹ Institute of Psychiatry, De Crespigny Park, London, SE5 8AF

The outstanding feature of scientific advance is its capacity for self-correction. This cannot be accounted for on the basis of inductive reasoning. It would not be enough to accumulate observations and then invent theories to account for them, for such conjectures would have no power to compel conviction, and a variety of theories could be advanced and held according to taste. In science theories are advanced, are criticized, are destroyed or survive criticism, and then perhaps become part of a generally accepted scientific world-view. It is important to be able to distinguish those argumentative processes which are capable of compelling conviction from those which may leave differences of opinion for ever unresolved. Karl Popper has proposed a criterion of demarcation for this purpose: a scientific theory is indeed a guess or conjecture, but is one which is capable of refutation. It is a generalization, a universal statement, which can be disproved by showing a contrary instance. If the theory explains how things happen one way, it denies that they happen another way, and it is the prohibition that matters, because this is what can be tested. The test is made by attempting to produce one of the forbidden range of phenomena. If such attempts at refutation fail, the hypothesis is to that extent confirmed. But it is not proved, since there will be other implications than the ones tested, and a later test may still refute it. Our acceptance of scientific theories is always provisional. This requires an attitude in the scientist of being willing to be proved wrong; though he may believe a theory, he should not be committed to it, or give it his unreserved loyalty.

A consequence of adopting Popper's criterion is that we are enabled to recognize, among all the theories purporting to give information about the empirical world, those which are worth scientific attention and those which are not. It is only theories which involve consequences capable of clashing with experience that are worth such attention. When we adopt a theory we must be able to say fairly precisely what observations we would accept as refuting it, and under what circumstances we should feel compelled to abandon it.

This criterion is a serviceable one, covering all that we think of as the empirical sciences. The criterion excludes, for instance, law, theology, and history, for in them no part is played by deductive reasoning from empirical observations. It equally excludes philosophy, logic and mathematics, disciplines not primarily concerned with observational subject matter and not dependent on it. If advance occurs in any of these fields, it is not because contentions are settled by the specific self-testing process which is at the heart of science. Popper's work still stands, when all the criticisms are heeded to which it has been subjected. The point has been justly made, by Kuhn and others, that scientists are various and conform to no invariable pattern in the way they work. We cannot deny that they are rooted in the ideologies of their era and their society, brainwashed by their teachers, blinded by prejudices, hogtied by obsessions, beguiled by will-o'-the-wisps, and at times even tempted to cheat and to lie. These lapses cause no more than eddies in a river. The curiosity of the scientist about the world, his rejection of authority and appeal to fact, lead to an information flow. Conjecture and refutation are integral to the flow, polarities necessarily engendered by the curiosity and the appeal. They are, in fact, higher order effects, and their interaction appertains to science and not to scientists.