On what inferentially justifies what: the vices of reliabilism and proper functionalism

Yet there are restrictions: a justified belief can inferentially justify a belief in some propositions but not others. Suppose I justifiably believe (J) that Jones ate pizza last night. My justified belief in J can, by itself, inferentially justify me in believing (S) that someone ate pizza last night. 2 Maybe I won’t be justified in believing S because I have a defeater. But S is at least a candidate for being justified solely by my justified belief in J. On the other hand, my justified belief in J cannot, by itself, inferentially justify me in believing (T) that Tommy tames tigers; T isn’t even a candidate for being justified solely by my justified belief in J. An adequate account of inferential justification needs to explain this difference, why a justified belief in J can inferentially justify a belief in S but not a belief in T. As a first pass, the more general question is this: what determines which propositions are candidates to be inferentially justified by a given justified belief? Reliabilism and proper functionalism may seem to deliver what we are looking for. A reliabilist can say that the relevant criterion can be supplied by differences in reliability. A justified belief in J can justify me in believing S, because J (conditionally 3 ) reliably indicates S; it can’t justify me in believing T, because J doesn’t reliably indicate T. The proper functionalist can say that the relevant criterion can be supplied by differences in proper function. A justified belief in J can justify me in believing S, because I’m designed to believe S on the basis of believing J; it can’t justify me in believing T, because I’m not designed to believe T in response to believing J. Despite the initial plausibility of reliabilism and proper functionalism, I argue that these views have counterintuitive implications. The underlying problem is that reliabilism and proper functionalism fail to place enough constraints on what can