falsification

falsification, falsificationism To falsify a knowledge-claim is to provide evidence that it is false. Since the time of David Hume, empiricist philosophy of science has struggled with the problem of induction: namely, how is it possible to justify inference, from a finite set of instances, to the truth of a universal law whose scope is potentially infinite? In the absence of a convincing answer to this question, our everyday and scientific belief in a regular, ordered, and predictable universe must seem to be a physiologically indispensable, but still irrational, habit of mind.

The original approach to this problem pioneered by Karl Popper involved a reasoned rejection of the question itself. Popper accepted that the problem of induction was insoluble, but it did not follow that science was irrational, or that it could not progress. Instead of seeing discovery of the truth as the aim of science, we should, rather, see scientific activity as a systematic attempt to ‘falsify’–or refute–bold and imaginative conjectures about the nature of the world.

Popper's formulation of this principle is widely acknowledged as one of the most original contributions to the modern philosophy of science. His work is often assimilated to the logical positivism of the Vienna Circle, but Popper was in fact (correctly) viewed by the latter as ‘the official opposition’. Certainly, Popper shared with the Vienna Circle a concern with what differentiated science from other approaches to knowledge and belief, and with passionate advocacy of scientific method. However, he differed from them in several important respects. First, he did not equate testability or scientificity with ‘meaningfulness’. For him, metaphysics, religion, myth, and other forms of discourse which fell on the ‘wrong’ side of the science/non-science division were still meaningful, and might even be true. Such systems of thought in any case formed the indispensable prehistory of properly scientific modes of enquiry. Furthermore, Popper did not follow the logical positivists in their search for indubitable ‘basic statements’ which reported sense-experience, and were crucial to verification.

Popper rejected the most characteristic doctrine of empiricism, in arguing (following Kant) that all descriptions of experiences involve selection and interpretation in terms of some prior conceptual framework, or theory. The model of scientific advance as an inductive process of generalization from particular experiences must therefore be rejected. Popper's alternative model is eloquently captured in the title of one of his books–Conjectures and Refutations (1963). Scientific theories are invented, by a process which cannot be captured by any logical scheme. Once invented, their scientific status is established by their fruitfulness in allowing the deduction of hypotheses which are ‘empirically contentful’. By this, Popper means that they should be highly improbable (in the sense that they rule out as impossible many happenings which might otherwise seem possible), and at the same time be clear and unambiguous in specifying what they rule out. In Popper's version, the empirical testing of a theory is not a matter of finding evidence to support or confirm it, but rather a matter of systematically attempting to show it to be false–a logic of refutation or falsification. In this way Popper avoids the problem of induction which had bedevilled the attempt to justify science in terms of the idea of empirical verification. Popper's position is based on recognition of a very simple asymmetry between the logic of verification and that of falsification in relation to the law-like generalizations of science: universal claims always go beyond what is strictly justified by the (finite) body of evidence for them, but may be decisively refuted by a single counter-instance.

But the situation is more complex than this. Most especially, although the logic of falsification may be simple, its methodology is not. An observation which appears to challenge an established theory may itself be challenged as fraudulent, methodologically suspect, and so on, and will always leave advocates of the theory a range of choices to modify their theory, short of wholesale abandonment. Popper is fully aware of this, and is inclined to present falsificationism as a normative injunction, rather than as a description of the actual practice of scientists. Nevertheless, choice between rival theories is never an arbitrary matter. Although all scientific knowledge must be considered provisional (there is no conclusive proof or disproof), scientists properly prefer, among rival theories which are so far unfalsified and account for the known facts, that theory which has most empirical content.

Popper's colleague, Imre Lakatos, developed a still more complex form of falsificationism in response to the historically based conventionalist arguments of Thomas S. Kuhn, Paul Feyerabend, and others (see ‘Falsification and the Methodology of Scientific Research Programmes’, in I. Lakatos and and A. Musgrave ( eds.) . Criticism and the Growth of Knowledge, 1970
).