Information, belief, and possibility.

According to a plausible picture of information, to acquire information is to rule out possibilities. What is the nature of these possibilities? The most natural answer---that they are (really) possible states of the world---seems to be refuted by the existence of informative truths that are (really) necessary, and so don't rule out any real possibilities. This seems to show that informational contents cannot be identified with the real possibilities they eliminate. Real possibilities, it seems, are too coarse-grained to do the work of informational contents. In the first part of the dissertation, I look at two defenses of the coarse-grained conception of content. First, Stalnaker has claimed that the informativeness of necessary truths can be explained within a two-dimensional semantic framework, in which necessary truths have contingent metalinguistic contents. In Chapter 1, I argue that this metalinguistic approach misconstrues the content of mathematical truths. Second, Stalnaker has claimed that we have independent reason to adopt a coarse-grained conception of content since naturalistic views of content such as indicator views allow only for coarse-grained contents. In Chapter 2, I argue that both indicator and teleological views allow for more fine-grained contents and that, given certain assumptions, they even require them. Together, these arguments show that the best attempt to explain the informativeness of necessary truths in terms of coarse-grained entities fails, and that naturalism gives us no reason for thinking that some other attempt will succeed. Instead of explaining informativeness in terms of the elimination of real possibilities, I claim, we should explain it in terms of the elimination of more fine-grained epistemic possibilities. In the second part of the dissertation, I describe the characteristic features of epistemic possibilities. Chapter 3 clarifies the relevant sense of epistemic possibility by distinguishing it from related senses that have gone under the same name. I argue that P is epistemically possible (in the relevant sense) for a thinker at a time just in case an operative belief that P is compatible with his operative beliefs at this time, where beliefs are called compatible, not if their contents are compatible, but if the beliefs themselves are compatible in the sense that it is possible to have them at the same time. Since epistemic possibility in this sense is a matter of what it is possible to believe, I call it epistemic possibility in the believability sense. In Chapter 4, I turn to the question of what sort of thing epistemic possibilities are. I argue that epistemic possibilities can be defined in terms of, but not identified with, a certain kind of fine-grained content.Ph.D.PhilosophyPhilosophy, Religion and TheologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124526/2/3150058.pd