The burden of proof

William James coined the term “radical empiricism” to mean a philosophy that includes as objects of experience particular things, relations and values. But I use the label to designate something quite different; it is the view that there are no a priori beliefs.

In order to evaluate the theories of apriority that we are examining, I need to put them into context. We need, in particular, to see whether philosophy without the a priori is viable and what, if anything, one needs to relinquish in order to get rid of the a priori. In this chapter, we shall look briefly at the history of radical empiricism and then in some depth at four radical empiricists – Mill, C. S. Peirce, Quine and Gilbert Harman.

The main question we need to ask in this chapter is: why do we need to think that there are a priori beliefs? In Chapter 1, we said that the a priori is useful in helping us understand how we can have knowledge about necessity and about certain types of normativity, especially moral obligations. Mill, Quine and Harman think we cannot know about what is necessarily true. Quine goes so far as to attack the notion of necessity itself. Harman thinks there are no moral facts in any strong sense, and he thinks moral knowledge is easily obtained, but is not the sort of knowledge many philosophers have taken it to be.