Empiricism has traditionally been concerned with two questions: What is the source of our concepts and ideas? and How should claims to empirical knowledge be judged? The empiricist answer to the first question is ‘From observation or experience.’ The concern in the second question is not to ground science in pure observation or in direct experience, but rather to ensure that claims to scientific knowledge are judged against the natural phenomena themselves. Questions about nature must be settled by nature — (...) not by faith, nor metaphysics, nor mathematics, and not by convention or convenience either. From Francis Bacon to Karl Popper empiricists have wanted to police the methods of scientific enquiry. (shrink)