Brit. J. Phil. Sci. 59 (2008), 89–119
What Evidence Do You Have? Ram Neta
ABSTRACT
Your evidence constrains your rational degrees of confidence both locally and globally. On the one hand, particular bits of evidence can boost or diminish your rational degree of confidence in various hypotheses, relative to your background information. On the other hand, epistemic rationality requires that, for any hypothesis h, your confidence in h is proportional to the support that h receives from your total evidence. Why is it that your evidence has these two epistemic powers? I argue that various proposed accounts of what it is for something to be an element of your evidence set cannot answer this question. I then propose an alternative account of what it is for something to be an element of your evidence set. 1 Introduction 2 The elements of one’s evidence set are propositions 3 Which kinds of propositions are in one’s evidence set? 3.1 Doxastic accounts of evidence 3.2 Non-doxastic accounts of evidence 4 Elaborating and defending the LIE
1 Introduction
Your evidence constrains your epistemically rational degrees of confidence in two ways. First, and most obviously, your evidence locally constrains your epistemically rational degrees of confidence, as follows: for any bit of evidence that you have, it is possible for you to use that evidence in the rational regulation of your degrees of confidence, or of your attitudes more generally. Relative to your background information, particular bits of your evidence thereby boost your rational degrees of confidence in some hypotheses, and diminish your rational degrees of confidence in others. Second, and less obviously, your evidence globally constrains your epis- temically rational degrees of confidence, as follows: for any hypothesis h, your confidence in h at a particular time t should be—as a matter of epis- temic rationality—proportional to the degree to which the total evidence that you possess at t supports h. Epistemic rationality does not require that your