Abductivists claim that explanatory considerations (e.g., simplicity, parsimony, explanatory breadth, etc.) favor belief in the external world over skeptical hypotheses involving evil demons and brains in vats. After showing how most versions of abductivism succumb fairly easily to obvious and fatal objections, I explain how rationalist versions of abductivism can avoid these difficulties. I then discuss the most pressing challenges facing abductivist appeals to the a priori and offer suggestions on how to overcome them.

I think that the epistemological theory presented by Plantinga would be more plausible if it were amended in a way that would be consistent with the no-foundations view suggested above. We have considered in detail his conception of basic beliefs in Section II above, and noted that his conception of basicality was obscure. For Plantinga, beliefs are basic only under certain conditions, and this is an obscure notion of basicality because unlike basic beliefs in a more traditional foundationalist theory, there (...) is no incorrigibility at the foundation, with no suitable substitute. Consequently, a foundationalist like Plantinga is faced with the same problem he thinks is inherent in coherentism; namely, how warrant for the noetic structure is guaranteed.In fact, it is unclear how Plantinga's version of foundationalism differs significantly from Williams' no-foundations view. If the noetic structure is potentially unlimited in the way that I have suggested, one could have a temporally local foundationalism which is consistent with Williams' no-foundations view, for all of Williams' arguments attack the notion of ultimate warrant for the noetic structure. And if, at a given time, a person takes certain beliefs in their noetic structure as basic contingent upon subsequent assessment of those beliefs, we have something very much like Plantinga's foundationalism. Such beliefs would be ‘basic’ in the sense of being non-inferentially credible, but this would not entail their functioning as grounds for the noetic structure as a whole, for the element lacking in this no-foundations view is the certain sort of experience which Plantinga thinks is necessary as a ground of the basic belief. But given the problems discussed above concerning criteria for basicality and the consequent problems concerning the identification of what sorts of experience function as a suitable ground, it is unclear in what way Plantinga's position is preferable.Plantinga's fundamental objection to a coherence view of justification was that there is no way of accounting for ultimate warrant for a noetic structure. But in reference to his own theory, Plantinga states that:The justification-conferring conditions mentioned above must be seen as conferring prima facie rather than ultima facie, or all-things-considered justification. This justification can be overridden. (“Reason”, 83)If, however, basic beliefs are merely prima facie justified and can be overridden, then there is no accounting for ultimate warrant in theological foundationalism either. Basic beliefs in a foundationalist position are supposed to serve the function of providing an end to the process of justification, but they do not serve this function in Plantinga's system. In defending the no-foundations view of justification, Williams recognizes that some beliefs are in fact accepted as non-inferentially credible or that some beliefs happen to be reliable (86, 94). If this is all that basic beliefs amount to, i.e. beliefs that are prima facie credible yet still defeasible, then theological foundationalism may as well scrap any hope of supplying adequate grounds for a noetic structure. Although more recent developments of foundationalism and coherentism, e.g. Laurence BonJour's The Structure of Empirical Knowledge (Cambridge: Harvard University Press, 1985) and William P. Alston's Epistemic Justification (Ithaca: Cornell University Press, 1989), contain refinements of the two theories which, ultimately, need to be considered in order to resolve the problems I raise here for theological foundationalism, I do not think these refinements significantly affect the arguments I present in this paper. In any case, I am considering these modifications in a work in progress. (shrink)

The abductivist reply to skepticism is the view that commonsense explanations of the patterns and regularities that appear in our sensory experiences should be rationally preferred to skeptical explanations of those same patterns and regularities on the basis of explanatory considerations. In this article I critically examine Laurence BonJour’s rationalist version of the abductivist position. After explaining why BonJour’s account is more defensible than other versions of the view, I argue that the notion of probability he relies upon is deeply (...) problematic, that he incorporates an implausible double-standard concerning a priori and a posteriori justification, and that his view is vulnerable to skepticism about the a priori. I suggest that some of these problems are due to idiosyncratic commitments BonJour makes and that abductivists would be better off without them. I conclude with some suggestions about how to improve BonJour’s abductivist response to skepticism. (shrink)

Abstract This paper develops an explanationist treatment of the problem of the criterion. Explanationism is the view that all justified reasoning is justified in virtue of the explanatory virtues: simplicity, fruitfulness, testability, scope, and conservativeness. A crucial part of the explanationist framework is achieving wide reflective equilibrium. I argue that explanationism offers a plausible solution to the problem of the criterion. Furthermore, I argue that a key feature of explanationism is the plasticity of epistemic judgments and epistemic methods. The explanationist (...) does not offer any fixed judgments or methods to guide epistemic conduct; even the explanatory virtues themselves are subject to change. This feature of explanationism gives it an advantage over non-explanationist views that offer fixed epistemic judgments and epistemic methods. The final section of this paper responds to objections to explanationism. (shrink)

Ongoing knowledge is that knowledge that a person possesses continuously across a period of time. Given the plausible assumption that knowledge implies justification, it then follows that ongoing knowledge implies ongoing justification. However, the actual character of a person's justification for a belief often changes as time passes. Two types of changes in one's ongoing justification are explored: content change and structure change. It is argued that justification held over time often undergoes both content and structure change, and that the (...) latter sort of change has interesting implications for theories of epistemic justification. (shrink)

I argue that there are Leibnizian-style cosmological arguments for the existence of God which start from very mild premises which affirm the mere possibility of a principle of sufficient reason. The utilization of such premises gives a great deal of plausibility to such types of argumentation. I spend the majority of the paper defending three major objections to such mild premises viz., a reductio argument from Peter van Inwagen and William Rowe, which proffers and defends the idea that a necessary (...) proposition cannot explain a contingent one. I, then, turn to an amelioration of the Rowe/van Inwagen argument which attempts to appeal to an entailment relation between explanans and explanandum that is fettered out in terms of relevance logic. Subsequent to dispelling with that worry, I tackle objections to the utilization of weak principles of sufficient reason that depend essentially upon agglomerative accounts of explanation. (shrink)