“I don’t know whether God exists or not. We may know how little we know, but this must not be turned or twisted into a positive knowledge of the existence of an unfathomable secret. There is a lot in the world that is in the nature of an unfathomable secret, but I do not think that it is admissible to make a theology out of a lack of knowledge nor turn our ignorance into anything like positive knowledge. Some forms of atheism are arrogant and ignorant and should be rejected, but agnosticism–to admit that we don’t know and to search–is all right.”

Karl Popper, The Enemy of Certainty, by Liz Williams

The search for truth was, Popper considered, the strongest motivation for scientific discovery. His role was to determine how we can ascribe truth to the claims made by science, religion and politics. He did not, however, become a member of the Vienna Circle, that group of intellectuals who, following on from the work of Wittgenstein (the Tractatus mark-one version of that philosopher) aimed at the unification of the sciences and the wholesale rejection of metaphysics. Popper’s antipathy to Wittgenstein meant that he was not invited to become a member of this particular group, but being cast in the role of the formal opposition seems to have honed his own thinking on logical positivism. Following on from Hume and the latter’s rejection of induction, Popper took a stand against an empiricist view of science, endeavouring to show via his rejection of verificationism, and consequent espousal of falsificationism, how scientific theories progress. We will be looking at this more closely in future articles, but the fundamental principle of falsificationism is this: any contradictory instance to a theory is sufficient to falsify that theory, regardless of how many positive examples appear to support it.

The Problem of Demarcation

Popper accordingly repudiates induction and rejects the view that it is the characteristic method of scientific investigation and inference, substituting falsifiability in its place. It is easy, he argues, to obtain evidence in favour of virtually any theory, and he consequently holds that such ‘corroboration’, as he terms it, should count scientifically only if it is the positive result of a genuinely ‘risky’ prediction, which might conceivably have been false. For Popper, a theory is scientific only if it is refutable by a conceivable event. Every genuine test of a scientific theory, then, is logically an attempt to refute or to falsify it, and one genuine counter-instance falsifies the whole theory. In a critical sense, Popper’s theory of demarcation is based upon his perception of the logical asymmetry which holds between verification and falsification: it is logically impossible to conclusively verify a universal proposition by reference to experience (as Hume saw clearly), but a single counter-instance conclusively falsifies the corresponding universal law. In a word, an exception, far from ‘proving’ a rule, conclusively refutes it.