Truth and conspiracy

A nice companion to my 2010 post:

For the simple truth is that truth is often hard to come by, and that once found it may easily be lost again. Erroneous beliefs may have an astonishing power to survive, for thousands of years, in defiance of experience, with or without the aid of any conspiracy. The history of science, and especially of medicine, could furnish us with a number of good examples. One example is, indeed, the general conspiracy theory itself I mean the erroneous view that whenever something evil happens it must be due to the evil will of an evil power. Various forms of this view have survived down to our own day.

(Karl Popper, from the Annual Philosophical Lecture read before the British Academy on January 20th, 1960. First published in the Proceedings of the British Academy, 46, 1960, and separately by Oxford University Press, 1961).