Thoughts in a Haystack

In [Sir Karl] Popper's view then, there are two contexts in which we might investigate the history of science and the story of how certain theories come to be developed and accepted, namely the context of discovery and the context of justification. This view accords with an intuition about the autonomy of ideas from the people that have them. It is no argument against vegetarianism to point out that Hitler was a vegetarian; similarly it is no argument against Newtonian mechanics to point out that Newton was an alchemist, and had an obsessive interest in the apocryphal books of the Bible. On the other hand, it is no argument for pacifism to point out that Einstein was a pacifist. In general, the evidence in favour of a hypothesis is independent of who believes it and who doesn't, and whether an idea really is a good one is not at all dependent on whether it is a genius or a fool who first thinks of it. It seems plausible to argue that an evaluation of the evidence for a hypothesis ought to take no account of how, why and by whom the hypothesis was conceived. Some such distinction between the causal origins of scientific theories and their degree of confirmation is often thought to be important for the defence of the objectivity of scientific knowledge.

- James Ladyman, Understanding the Philosophy of Science