The Logic of Scientific Discovery

In one majestic and systematic attack, psychologism, naturalism, inductionism, and logical positivism are swept away and replaced by a set of methodological rules called Falsificationism. Falsificationism is the idea that science advances by unjustified, exaggerated guesses followed by unstinting criticism. Only hypotheses capable of clashing with observation reports are allowed to count as scientific. "Gold is soluble in hydrochloric acid" is scientific (though false); "Some homeopathic medicine does work" is, taken on its own, unscientific (though possibly true). The first is scientific because we can eliminate it if it is false; the second is unscientific because even if it were false we could not get rid of it by confronting it with an observation report that contradicted it. Falsifiable theories enhance our control over error while expanding the richness of what we can say about the world.

Any "positive support" for theories is unobtainable and superfluous; all we can do is eliminate error - and even this is hypothetical, though often successful. The notion that science offers proof is now only advanced by popular treatments of science on TV and in (many) newspapers. Many journalists are sadly completely devoid of theoretical knowledge: a side-effect of overspecialization on the immediate moment.

Realism and the Aim of Science

Look out for this travesty of Popper's analysis: "You cannot prove a theory, but you can disprove it". Proof is a matter of demonstration (as in mathematics), but refutation is a matter of accepting a basic statement and rejecting the truth of the theory it contradicts. If I accept "This swan here is black", then I am obliged to reject "All swans are white". Because from "This swan here is black" I can derive "Not all swans are white". But I have not proved that not all swans are white, that this must be true. In a proof, we discard the assumptions that helped us to get to the conclusion. This is quite clear in proof by reductio ad absurdum. In a reductio ad absurdum we start by assuming the opposite of what we wish to prove. That is, we assume it is false. We then try to infer an absurdity (contradiction) from this, and if we do, we then conclude that the assumption must be true. But in a refutation, our rejection of a theory, "All swans are white", depends on our maintaining the truth of the basic statement, "This swan here is black". In a refutation we hold on to the assumptions of our derivation. Of course, the derivations involved in science are much more complex than in the swan example, but the point stands.