At the core of evidentialism lies a very plausible claim: rational thinkers follow their evidence. While this seems to be a very intuitive, almost trivial, claim, providing a full and complete evidentialist theory is complicated. In this entry, I begin with elucidating what kind of theory evidentialists aim to provide us with. I will show that, in order to provide a complete evidentialist theory, we have to provide a lot of details on what evidence is and how it relates to (...) the proposition it’s evidence for, as well as the agent possessing such evidence. I then consider objections arising for the most popular answers one can give to such questions. I conclude by considering old and new challenges that arise for evidentialism, regardless of the specific version one endorses. (shrink)

Some philosophers think that knowledge or justification is both necessary and sufficient for rational action: they endorse knowledge-action or justification-action biconditionals. This paper offers a novel, metaphysical challenge to these biconditionals, which proceeds with a familiar question: What depends on what? If you know that p iff it is rational for you to act on p, do you know that p partly because it is rational for you to act on p, or is it rational for you to act on (...) p partly because you know that p? And a structurally similar question can be asked regarding justification-action biconditionals. I argue that proponents of these biconditionals cannot give a satisfactory answer to these questions. This is because each direction of these biconditionals strongly supports an opposite order of explanation to the one that is supported by the other direction. Given the traditional assumption that metaphysical explanations—even partial ones—are asymmetric, I argue that these biconditionals should be rejected. While knowledge might be necessary for rational action, and it might be sufficient, it cannot be both. And the same goes for justification. (shrink)

The received view says that possibility is the dual of necessity: a proposition is (metaphysically, logically, epistemically etc.) possible iff it is not the case that its negation is (metaphysically, logically, epistemically etc., respectively) necessary. This reading is usually taken for granted by modal logicians and indeed seems plausible when dealing with logical or metaphysical possibility. But what about epistemic possibility? We argue that the dual definition of epistemic possibility in terms of epistemic necessity generates tension when reasoning about non-idealized (...) agents and is a problem of concern for most hyperintensional epistemic logics that alleviate the problem of logical omniscience. The tension is particularly evident when knowledge is taken as a primitive to define other epistemic concepts, such as justification and belief, as done in the knowledge-first tradition. We propose a non-dual interpretation of epistemic possibility, employing a hyperintensionality filter similar to the one that makes the corresponding epistemic necessity operator hyperintensional. We employ the proposed semantics to model Stalnaker's belief as epistemic possibility of knowledge and provide a sound and complete axiomatization for a hyperintensional version of his bimodal logic of knowledge and belief. (shrink)

Ascriptions of rationality are related to our practices of praising and criticizing. This seems to provide motivation for normative accounts of rationality, more specifically for the view that rationality is a matter of responding to normative reasons. However, rational agents are sometimes guided by false beliefs. This is problematic for those reasons-based accounts of rationality that are also committed to the widespread thesis that normative reasons are facts. The critical aim of the paper is to present objections to recent proposed (...) solutions to this problem, according to which the responses of deceived agents would be rationalized by facts about how things appear to them. My positive aim is to argue that accounts of reasons in terms of apparent reasons manage to capture the intuitions that seem to favor a normative account of rationality. (shrink)

The paper investigates what type of motivation can be given for adopting a knowledge-based decision theory. KBDT seems to have several advantages over competing theories of rationality. It is commonly argued that this theory would naturally fit with the intuitive idea that being rational is doing what we take to be best given what we know, an idea often supported by appeal to ordinary folk appraisals. Moreover, KBDT seems to strike a perfect balance between the problematic extremes of subjectivist and (...) objectivist decision theory. We argue that these alleged advantages do not stand up to a closer scrutiny: KBDT inherits the same kinds of problems as alternative decision theoretic frameworks but doesn’t retain any of the respective advantages. Moreover, differently from other knowledge-action principles advanced in the literature, KBDT cannot fully explain the intuitive connections between knowledge and rational action. We conclude that the most serious challenge for knowledge-based decision theorists is to provide a substantive rationale for the adoption of such a view. (shrink)