The intensity of a conviction that a hypothesis is true has no bearing on whether it is true or false. The importance of the strength of our conviction is only to provide a proportionately strong incentive to find out if the hypothesis will stand up to critical evaluation.

Considered in its entirety, psychoanalysis won't do. It is an end product, moreover, like a dinosaur or a zeppelin; no better theory can ever be erected on its ruins, which will remain for ever one of the saddest and strangest of all landmarks in the history of twentieth century thought.

In no sense other than an utterly trivial one is reproduction the inverse of chemical disintegration. It is a misunderstanding of genetics to suppose that reproduction is only 'intended' to make facsimiles, for parasexual processes of genetical exchange are to be found in the simplest living things.

If politics is the art of the possible, research is surely the art of the soluble. Both are immensely practical-minded affairs.

Innocent, unbiased observation is a myth.

[A certain class of explanations in science are] analgesics that dull the ache of incomprehension without removing the cause.

The art of research [is] the art of making difficult problems soluble by devising means of getting at them.