Evidentialism: Concepts, content, and epistemological unity.

摘要

Evidentialist theories of epistemic justification endorse the thesis that one is justified in believing a proposition at a time if and only if one's evidence at that time supports one's believing that proposition. In this dissertation I consider and address two main objections to this thesis. I then conclude by considering the extent to which a general requirement on epistemic justification implicit in previous chapters can unify the various epistemic principles that constitute evidentialism.The first objection I consider depends on a thesis prominent in recent philosophy of language. According to this thesis, the proposition that Hesperus is visible in the evening is identical to the proposition that Phosphorus is visible in the evening. But it seems that one can rationally believe that Hesperus is visible in the evening while at the same time rationally disbelieving that Phosphorus is visible in the evening. Some take this to show that one can believe (or fail to believe) a proposition in various ways, or under different guises. If all of this is correct, then standard formulations of evidentialism are false. The evidentialist thesis needs to be revised so that the primary objects of epistemic appraisal are not propositions, but rather "ways of believing" propositions, where a way of believing a proposition is just the guise under which the proposition is believed.I defend the epistemic judgments involved in this argument against standard formulations of evidentialism and develop a revised version of the evidentialist thesis. I show that the required revision to the evidentialist thesis demands substantive changes to its accompanying theory of evidence. Nevertheless, I argue that the changes to evidentialism forced by these semantic considerations do not provide any insurmountable difficulties for evidentialism. The second objection that I consider is a descendent of the traditional problem of the speckled hen. Briefly, the problem of the speckled hen shows that traditional evidentialist accounts of the justification of introspective and empirical beliefs are false. Contrary to what they entail, having the appearance-state of a 48-speckled hen is not sufficient for being justified in believing either that one is having the perceptual state of a 48-speckled hen, or that a 48-speckled hen is before one. Intuitively, it seems one also needs to have the ability to discriminate 48-speckles from similar amounts of speckles in order for one's experience to provide one with adequate justification for believing either proposition. Thus, at a very general level, the problem of the speckled hen challenges evidentialism because it appears to show that not only one's evidence, but also one's discriminatory capacities, determine what one is justified in believing. I critically evaluate two accounts of the justification of introspective belief specifically formulated to overcome this problem. I argue that they fail, and I develop my own account of the justification of introspective belief, utilizing insights gleaned from the earlier discussion.The discussion of these two objections suggests that some substantive "subjective" conception of epistemic justification is true. In the final chapter I sketch some subjective interpretations of the key terms of the evidentialist thesis that can help to guide future work. By so doing, these interpretations of those terms also will help to unify the various epistemic principles evidentialism admits.