Joshua Schechter

A consequence relation is strongly classical if it has all the theorems and entailments of classical logic as well as the usual meta-rules (such as Conditional Proof). A consequence relation is weakly classical if it has all the theorems and entailments of classical logic but lacks the usual meta-rules. The most familiar example of a weakly classical consequence relation comes from a simple supervaluational approach to modelling vague language. This approach is formally equivalent to an account of logical consequence according to which α1, ..., αn entails β just in case □α1, ..., □αn entails □β in the modal logic S5. This raises a natural question: If we start with a different underlying modal logic, can we generate a strongly classical logic? This paper explores this question. In particular, it discusses four related technical issues: (1) Which base modal logics generate strongly classical logics and which generate weakly classical logics? (2) Which base logics generate themselves? (3) How can we directly characterize the logic generated from a given base logic? (4) Given a logic that can be generated, which base logics generate it? The answers to these questions have philosophical interest. They can help us to determine whether there is a plausible supervaluational approach to modelling vague language that yields the usual meta-rules. They can also help us to determine the feasibility of other philosophical projects that rely on an analogous formalism, such as the project of defining logical consequence in terms of the preservation of an epistemic status.

How should we understand validity? A standard way to characterize validity is in terms of the preservation of truth (or truth in a model). But there are several problems facing such characterizations. An alternative approach is to characterize validity epistemically, for instance in terms of the preservation of an epistemic status. In this paper, I raise a problem for such views. First, I argue that if the relevant epistemic status is factive, such as being in a position to know or having conclusive evidence for, then the account runs into trouble if we endorse certain familiar logical principles. Second, I argue that if the relevant epistemic status is non-factive, such as is rationally committed to or has justification for believing, then a similar problem arises if we endorse the logical principles as well as a sufficiently strong epistemic “level-bridging” principle. Finally, I argue that an analogous problem arises for the most natural characterization of validity in terms of rational credence.

Learning information about the etiology of one's beliefs can reduce the justification a thinker has for those beliefs. Learning information about the etiology of one's desires, emotions, or concepts can similarly have a debunking effect. In this chapter, I develop a unified account of etiological debunking that applies across these different kinds of cases. According to this account, etiological debunking arguments work by providing reason to think that there is no satisfying explanation of how it is that some part of our mental life is fitting. The role that etiological information plays is to help to rule out (or render less plausible) potential explanations, given our background views about the world. This account suggests several potential morals for epistemology, the philosophy of mind, and metaethics.

This chapter discusses epistemic objections to non-naturalist moral realism. The goal of the chapter is to determine which objections are pressing and which objections can safely be dismissed. The chapter examines five families of objections: (i) one involving necessary conditions on knowledge, (ii) one involving the idea that the causal history of our moral beliefs reflects the significant impact of irrelevant influences, (iii) one relying on the idea that moral truths do not play a role in explaining our moral beliefs, (iv) one involving the claim that if moral realism is true then our moral beliefs are unlikely to be reliable, and (v) one involving the claim that moral realism is incompatible with there being a plausible explanation of our reliability about morality. The overall conclusion of the chapter is that the final objection is by far the most pressing.

In this paper, we develop an account of the justification thinkers have for employing certain basic belief-forming methods. The guiding idea is inspired by Reichenbach's work on induction. There are certain projects in which thinkers are rationally required to engage. Thinkers are epistemically justified in employing any belief-forming method such that "if it doesn't work, nothing will" for successfully engaging in such a project. We present a detailed account based on this intuitive thought and address objections to it. We conclude by commenting on the implications that our account may have for other important epistemological issues and debates.

In recent years, several philosophers have argued that the a priori/a posteriori distinction is a legitimate distinction but does not carve at the epistemological joints and is theoretically unimportant. In this paper, I do two main things. First, I respond to the most prominent recent challenge to the significance of the a priori/a posteriori distinction – the central argument in Williamson (2013). Second, I discuss the question of what the theoretical significance of the a priori/a posteriori distinction is. I first present the a priori/a posteriori distinction as it is typically developed. I then turn to Williamson’s challenge to the significance of the distinction. Williamson points out that we often use the same cognitive mechanisms in coming to have a priori and a posteriori knowledge. So how could it be, asks Williamson, that there is a “deep epistemological difference” between the two? In response to this challenge, I argue that there is an important disanalogy between Williamson’s central example of a case of a priori knowledge and his central example of a case of a posteriori knowledge. Although the beliefs in the two cases are formed in similar ways, the ways in which their justification can be defeated are different. This suggests that there is an important epistemological difference between the two cases, one that cannot be captured in terms of the cognitive mechanisms used to form the beliefs. Although Williamson’s argument is unsuccessful, there remains the question of just what the theoretical significance of the a priori/a posteriori distinction is. I argue that the point of the distinction is not to enable us to represent some joint in nature, but rather to help us to identify epistemological problem cases. We understand – more-or-less – the epistemology of simple perceptual knowledge. The epistemology of non-perceptual knowledge is far less clear. The purpose of labeling a case of knowledge as a priori is to claim that its epistemology should not be assimilated to the epistemology of perception. Instead, it is something of a puzzle case. This proposal has an important implication. There are several ways in which a case of knowledge can be different from a simple case of perceptual knowledge. Two differences are perhaps the most important: (i) the justification of the belief does not involve phenomenality, and (ii) the belief does not stand in a causal relation to what the belief is about. When beliefs about some subject matter fit either (i) or (ii), an epistemological puzzle arises. So there is more than one kind of epistemological puzzle to solve. This suggests that there is an important theoretical role for (at least) two distinctions in the ballpark of the traditional a priori/a posteriori distinction.

This paper discusses Ernest Sosa's account of knowledge and epistemic normativity. The paper has two main parts. The first part identifies places where Sosa's account requires supplementation if it is going to capture important epistemic phenomena. In particular, additional theoretical resources are needed to explain the way in which epistemic aims are genuinely good aims, and the way in which some forms of reasoning can be epistemically better than others even when they are equally conducive to attaining the truth. The second part focuses on Sosa's claim that there is a kind of belief – judgmental belief – that doesn't merely aim at truth but also aims at aptness, and that this kind of belief is central to our mental lives. The paper raises several concerns about this part of Sosa's account, including the concern that aiming at aptness is overly self-directed, and so is more closely tied to vice than epistemic virtue.

There are many domains about which we think we are reliable. When there is prima facie reason to believe that there is no satisfying explanation of our reliability about a domain given our background views about the world, this generates a challenge to our reliability about the domain or to our background views. This is what is often called the reliability challenge for the domain. In previous work, I discussed the reliability challenges for logic and for deductive inference. I argued for four main claims: First, there are reliability challenges for logic and for deduction. Second, these reliability challenges cannot be answered merely by providing an explanation of how it is that we have the logical beliefs and employ the deductive rules that we do. Third, we can explain our reliability about logic by appealing to our reliability about deduction. Fourth, there is a good prospect for providing an evolutionary explanation of the reliability of our deductive reasoning. In recent years, a number of arguments have appeared in the literature that can be applied against one or more of these four theses. In this paper, I respond to some of these arguments. In particular, I discuss arguments by Paul Horwich, Jack Woods, Dan Baras, Justin Clarke-Doane, and Hartry Field.

We are justified in employing the rule of inference Modus Ponens (or one much like it) as basic in our reasoning. By contrast, we are not justified in employing a rule of inference that permits inferring to some difficult mathematical theorem from the relevant axioms in a single step. Such an inferential step is intuitively “too large” to count as justified. What accounts for this difference? In this paper, I canvass several possible explanations. I argue that the most promising approach is to appeal to features like usefulness or indispensability to important or required cognitive projects. On the resulting view, whether an inferential step counts as large or small depends on the importance of the relevant rule of inference in our thought.

This paper develops a new framework for combining propositional logics, called "juxtaposition". Several general metalogical theorems are proved concerning the combination of logics by juxtaposition. In particular, it is shown that under reasonable conditions, juxtaposition preserves strong soundness. Under reasonable conditions, the juxtaposition of two consequence relations is a conservative extension of each of them. A general strong completeness result is proved. The paper then examines the philosophically important case of the combination of classical and intuitionist logics. Particular attention is paid to the phenomenon of collapse. It is shown that there are logics with two stocks of classical or intuitionist connectives that do not collapse. Finally, the paper briefy investigates the question of which rules, when added to these logics, lead to collapse.

In the first chapter of his Knowledge and Lotteries, John Hawthorne argues that thinkers do not ordinarily know lottery propositions. His arguments depend on claims about the intimate connections between knowledge and assertion, epistemic possibility, practical reasoning, and theoretical reasoning. In this paper, we cast doubt on the proposed connections. We also put forward an alternative picture of belief and reasoning. In particular, we argue that assertion is governed by a Gricean constraint that makes no reference to knowledge, and that practical reasoning has more to do with rational degrees of belief than with states of knowledge.

This paper concerns the epistemology of difficult moral cases where the difficulty is not traceable to ignorance about non-moral matters. The paper first argues for a principle concerning the epistemic status of moral beliefs about difficult moral cases. The basic idea behind the principle is that one’s belief about the moral status of a potential action in a difficult moral case is not justified unless one has some appreciation of what the relevant moral considerations are and how they bear on the moral status of the potential action. The paper then argues that this principle has important ramifications for moral epistemology and moral metaphysics. It puts pressure on some views of the justification of moral belief, such as ethical intuitionism and reliabilism. It puts pressure on some antirealist views of moral metaphysics, including simple versions of relativism. It also provides some direct positive support for broadly realist views of morality.

Closure for justification is the claim that thinkers are justified in believing the logical consequences of their justified beliefs, at least when those consequences are competently deduced. Many have found this principle to be very plausible. Even more attractive is the special case of Closure known as Single-Premise Closure. In this paper, I present a challenge to Single-Premise Closure. The challenge is based on the phenomenon of rational self-doubt – it can be rational to be less than fully confident in one's beliefs and patterns of reasoning. In rough outline, the argument is as follows: Consider a thinker who deduces a conclusion from a justified initial premise via an incredibly long sequence of small competent deductions. Surely, such a thinker should suspect that he has made a mistake somewhere. And surely, given this, he should not believe the conclusion of the deduction even though he has a justified belief in the initial premise.

Deductive reasoning is the kind of reasoning in which, roughly, the truth of the input propositions (the premises) logically guarantees the truth of the output proposition (the conclusion), provided that no mistake has been made in the reasoning. The premises may be propositions that the reasoner believes or assumptions that the reasoner is exploring. Deductive reasoning contrasts with inductive reasoning, the kind of reasoning in which the truth of the premises need not guarantee the truth of the conclusion.

There are several important arguments in metaethics that rely on explanatory considerations. Gilbert Harman has presented a challenge to the existence of moral facts that depends on the claim that the best explanation of our moral beliefs does not involve moral facts. The Reliability Challenge against moral realism depends on the claim that moral realism is incompatible with there being a satisfying explanation of our reliability about moral truths. The purpose of this chapter is to examine these and related arguments. In particular, this chapter will discuss four kinds of arguments – Harman’s Challenge, evolutionary debunking arguments, irrelevant influence arguments, and the Reliability Challenge – understood as arguments against moral realism. The main goals of this chapter are (i) to articulate the strongest version of these arguments; (ii) to present and assess the central epistemological principles underlying these arguments; and (iii) to determine what a realist would have to do to adequately respond to these arguments.

We think of logic as objective. We also think that we are reliable about logic. These views jointly generate a puzzle: How is it that we are reliable about logic? How is it that our logical beliefs match an objective domain of logical fact? This is an instance of a more general challenge to explain our reliability about a priori domains. In this paper, I argue that the nature of this challenge has not been properly understood. I explicate the challenge both in general and for the particular case of logic. I also argue that two seemingly attractive responses – appealing to a faculty of rational insight or to the nature of concept possession – are incapable of answering the challenge.

Since the publication of Timothy Williamson’s Knowledge and its Limits, knowledge-first epistemology has become increasingly influential within epistemology. This paper discusses the viability of the knowledge-first program. The paper has two main parts. In the first part, I briefly present knowledge-first epistemology as well as several big picture reasons for concern about this program. While this considerations are pressing, I concede, however, that they are not conclusive. To determine the viability of knowledge-first epistemology will require philosophers to carefully evaluate the individual theses endorsed by knowledge-first epistemologists as well as to compare it with alternative packages of views. In the second part of the paper, I contribute to this evaluation by considering a specific thesis endorsed by many knowledge-first epistemologists – the knowledge norm of assertion. According to this norm, roughly speaking, one should assert that p only if one knows that p. I present and motivate this thesis. I then turn to a familiar concern with the norm: In many cases, it is intuitively appropriate for someone who has a strongly justified belief that p, but who doesn't know that p, to assert that p. Proponents of the knowledge norm of assertion typically explain away our judgments about such cases by arguing that the relevant assertion is improper but that the subject has an excuse and is therefore not blameworthy for making the assertion. I argue that that this response does not work. In many of the problem cases, it is not merely that the subject’s assertion is blameless. Rather, the subject positively ought to make the assertion. Appealing to an excuse cannot be used to adequately explain this fact. (Nor can we explain this fact by appealing to some other, quite different, consideration.) Finally, I conclude by briefly considering whether we should replace the knowledge norm of assertion with an alternative norm. I argue that the most plausible view is that there is no norm specifically tied to assertion.

In our thought, we employ rules of inference and belief-forming methods more generally. For instance, we (plausibly) employ deductive rules such as Modus Ponens, ampliative rules such as Inference to the Best Explanation, and perceptual methods that tell us to believe what perceptually appears to be the case. What explains our entitlement to employ these rules and methods? This chapter considers the motivations for broadly internalist answers to this question. It considers three such motivations—one based on simple cases, one based on a general conception of epistemic responsibility, and one based on skeptical scenarios. The chapter argues that none of these motivations is successful. The first two motivations lead to forms of internalism—Extreme Method Internalism and Defense Internalism—that are too strong to be tenable. The third motivation motivates Mental Internalism (Mentalism), which does not fit with plausible accounts of entitlement.

There are well-known quasi-formal arguments that identity is a "strict" relation in at least the following three senses: (1) There is a single identity relation and a single distinctness relation; (2) There are no contingent cases of identity or distinctness; and (3) There are no vague or indeterminate cases of identity or distinctness. However, the situation is less clear cut than it at first may appear. There is a natural formal theory of identity that is very close to the standard classical theory but which does not validate the formal analogues of (1)-(3). The core idea is simple: We weaken the Principle of the Indiscernibility of Identicals from a conditional to an entailment and we adopt a weakly classical logic. This paper investigates this weakly classical theory of identity (and related theories) and discusses its philosophical ramifications. It argues that we can accept a reasonable theory of identity without committing ourselves to the uniqueness, necessity, or determinacy of identity.

We are reliable about logic in the sense that we by-and-large believe logical truths and disbelieve logical falsehoods. Given that logic is an objective subject matter, it is difficult to provide a satisfying explanation of our reliability. This generates a significant epistemological challenge, analogous to the well-known Benacerraf-Field problem for mathematical Platonism. One initially plausible way to answer the challenge is to appeal to evolution by natural selection. The central idea is that being able to correctly deductively reason conferred a heritable survival advantage upon our ancestors. However, there are several arguments that purport to show that evolutionary accounts cannot even in principle explain how it is that we are reliable about logic. In this paper, I address these arguments. I show that there is no general reason to think that evolutionary accounts are incapable of explaining our reliability about logic