Peter Graham

Radical skepticism about the external implies that no belief about the external is even prima facie justified. A theoretical reply to skepticism has four stages. First, show which theories of epistemic justification support skeptical doubts (show which theories, given other reasonable assumptions, entail skepticism). Second, show which theories undermine skeptical doubts (show which theories, given other reasonable assumptions, do not support the skeptic’s conclusion). Third, show which of the latter theories (which non-skeptical theory) is correct, and in so doing show that all of the rival theories of justification, skeptical and non-skeptical alike, are mistaken. Fourth, explain why skeptical doubts are sometimes (or sometimes merely seem) intuitive, and thereby accommodate skeptical doubts without capitulation. Michael Williams has pioneered the very idea of a theoretical reply. A theoretical diagnosis consists in just the first two stages. An adequate reply, which is correct at each stage, would rebut the skeptic entirely. Williams’ own reply, I argue, is inadequate. I offer in its place an exhaustive and accurate diagnosis of skepticism. I distinguish four kinds of skepticism and five theories of justification. I then show which theories do, and which theories do not, support which kinds of skepticism.

Our folk epistemology says that if someone knows that P and tells you that P, then, given the absence of defeaters, if you believe what they tell you, you will come to know that P as well. A speaker's knowledge that P is then, for the most part, enough for a hearer to come to know that P. But there are counterexamples to this principle: testimonial knowledge does not always transfer from the speaker to the hearer. Why should that be so? Because testimonial knowledge arises through the flow of information--from conclusive grounds--from the speaker through the speaker's assertion to the hearer's state of comprehension as of the speaker's assertion. A speaker's belief can be based on conclusive grounds, but the speaker's assertion may fail to provide conclusive grounds to the hearer. Then the hearer won't acquire knowledge, even from a knowledgeable speaker. Knowledge from testimony then works more like knowledge through perception. But wait, you say, that can't be so because testimony involves free will but perception does not. The essay ends with a broadly Hume inspired reply to this objection.

What is the best account of process reliabilism about epistemic justification, especially epistemic entitlement? I argue that entitlement consists in the normal functioning (proper operation) of the belief-forming process when the process has forming true beliefs reliably as an etiological function. Etiological functions involve consequence explanation: a belief-forming process has forming true beliefs reliably as a function just in case forming-true beliefs reliably partly explains the persistence of the process. This account paves the way for avoiding standard objections to process reliabilism and situations epistemic entitlement within a normative framework of functions and functional norms.

This paper argues for the general proper functionalist view that epistemic warrant consists in the normal functioning of the belief-forming process when the process has forming true beliefs reliably as an etiological function. Such a process is reliable in normal conditions when functioning normally. This paper applies this view to so-called testimony-based beliefs. It argues that when a hearer forms a comprehension-based belief that P (a belief based on taking another to have asserted that P) through the exercise of a reliable competence to comprehend and filter assertive speech acts, then the hearer's belief is prima facie warranted. The paper discusses the psychology of comprehension, the function of assertion, and the evolution of filtering mechanisms, especially coherence checking.

Reductionism about testimony holds that testimonial warrant or entitlement is just a species of inductive warrant. Anti-Reductionism holds that it is different from inductive but analogous to perceptual or memorial warrant. Perception receives much of its positive epistemic status from being reliably truthconducive in normal conditions. One reason to reject the epistemic analogy is that testimony involves agency – it goes through the will of the speaker – but perception does not. A speaker might always choose to lie or otherwise deliberately mislead. It is argued that the force of this derives (in part) from Libertarianism about agency, and that Libertarianism, if it undermines the Anti-Reductionist explanation of why we are entitled to rely upon testimony, undermines the Reductionist explanation as..