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. (shrink)

The aim of this paper is to sketch a theory of justified belief. What I have in mind is an explanatory theory, one that explains in a general way why certain beliefs are counted as justified and others as unjustified. Unlike some traditional approaches, I do not try to prescribe standards for justification that differ from, or improve upon, our ordinary standards. I merely try to explicate the ordinary standards, which are, I believe, quite different from those of many classical, (...) e. g., ‘Cartesian’, accounts. (shrink)

This paper defends a counterexample to Modus Tollens, and uses it to draw some conclusions about the logic and semantics of indicative conditionals and probability operators in natural language. Along the way we investigate some of the interactions of these expressions with 'knows', and we call into question the thesis that all knowledge ascriptions have truth-conditions.

This is a response to Paul Boghossian’s paper: What is inference?. The paper and the abstract originate from a symposium at the Pacific Division Meeting of the APA in San Diego in April 2011. John Broome was a co-commentator.

In this paper I am concerned with the question of whether degrees of belief can figure in reasoning processes that are executed by humans. It is generally accepted that outright beliefs and intentions can be part of reasoning processes, but the role of degrees of belief remains unclear. The literature on subjective Bayesianism, which seems to be the natural place to look for discussions of the role of degrees of belief in reasoning, does not address the question of whether degrees (...) of belief play a role in real agents’ reasoning processes. On the other hand, the philosophical literature on reasoning, which relies much less heavily on idealizing assumptions about reasoners than Bayesianism, is almost exclusively concerned with outright belief. One possible explanation for why no philosopher has yet developed an account of reasoning with degrees of belief is that reasoning with degrees of belief is not possible for humans. In this paper, I will consider three arguments for this claim. I will show why these arguments are flawed, and conclude that, at least as far as these arguments are concerned, it seems like there is no good reason why the topic of reasoning with degrees of belief has received so little attention. (shrink)

It seems beyond doubt that a thinker can come to know a conclusion by deducing it from premisses that he knows already, but philosophers have found it puzzling how a thinker could acquire knowledge in this way. Assuming a broadly externalist conception of knowledge, I explain why judgements competently deduced from known premisses are themselves knowledgeable. Assuming an exclusionary conception of judgeable content, I further explain how such judgements can be informative. (According to the exclusionary conception, which I develop from (...) some remarks in Ramsey, a judgement's content is given by the hitherto live possibilities that it excludes or rules out.) I propose that the value of logic lies in its allowing us to combine different sources of knowledge, so that we can learn things that we could not learn from those sources individually. I conclude by arguing that while single-conclusion logics possess that value, multiple-conclusion logics do not. (shrink)

It is tempting to think that multi premise closure creates a special class of paradoxes having to do with the accumulation of risks, and that these paradoxes could be escaped by rejecting the principle, while still retaining single premise closure. I argue that single premise deduction is also susceptible to risks. I show that what I take to be the strongest argument for rejecting multi premise closure is also an argument for rejecting single premise closure. Because of the symmetry between (...) the principles, they come as a package: either both will have to be rejected or both will have to be revised. (shrink)

The authors outline a theory of conditionals of the form If A then C and If A then possibly C. The 2 sorts of conditional have separate core meanings that refer to sets of possibilities. Knowledge, pragmatics, and semantics can modulate these meanings. Modulation can add information about temporal and other relations between antecedent and consequent. It can also prevent the construction of possibilities to yield 10 distinct sets of possibilities to which conditionals can refer. The mental representation of a (...) conditional normally makes explicit only the possibilities in which its antecedent is true, yielding other possibilities implicitly. Reasoners tend to focus on the explicit possibilities. The theory predicts the major phenomena of understanding and reasoning with conditionals. (shrink)

In this essay we argue that reasoning can sometimes generate epistemic justification, rather than merely transmitting justification that the subject already possesses to new beliefs. We also suggest a way to account for it in terms of the relationship between epistemic normative requirements, justification and cognitive capacities.

Carroll's short piece “What the Tortoise said to Achilles” in many ways anticipates issues that arise in a number of contemporary controversies. One might argue, for example, that initially plausible attempts to deal with the problem of easy knowledge will land one in the unfortunate position of Achilles who followed the Tortoise down a road that leads to vicious infinite regress. Or consider the conditions required for inferential justification. For idealized inferential justification, I have defended the view that to be (...) justified in believing P on the basis of E one needs to be not only justified in believing E, but justified in believing that E makes probable P. And again, critics have argued that such a strong requirement fails to learn the lesson that Achilles should have been taught by the Tortoise. Even more generally, one might well argue that strong access internalists will need to deal with a variation of Carroll's puzzle even for their accounts of non-inferential justification. In this paper I'll examine these controversies with a mind to reaching a conclusion about just exactly how one can accept intellectually demanding conditions on justified belief without encountering vicious regress. (shrink)

There are quite a few theses about logic that are in one way or another pluralist: they hold (i) that there is no uniquely correct logic, and (ii) that because of this, some or all debates about logic are illusory, or need to be somehow reconceived as not straightforwardly factual. Pluralist theses differ markedly over the reasons offered for there being no uniquely correct logic. Some such theses are more interesting than others, because they more radically affect how we are (...) initially inclined to understand debates about logic. Can one find a pluralist thesis that is high on the interest scale, and also true? (shrink)

I object to Markos Valaris’s thesis that reasoning requires a belief that your conclusion follows from your premisses. My counter-examples highlight the important but neglected role of suppositional reasoning in the basis of so much of what we know.

Access internalism about epistemic justification is the thesis that a person’s justification for a belief is directly accessible to that person, in the sense that the person can have direct awareness of whatever is functioning as the actual justification for the belief. This thesis is distinguished into a weak and a strong version, and a number of arguments in favor of the access internalist position are assessed. It is concluded that none of the arguments in support of access internalism is (...) satisfactory. (shrink)

The epistemic basing relation is the relation occurring between a belief and a reason when the reason is the reason for which the belief is held. It marks the distinction between a belief's being justifiable for a person, and the person's being justified in holding the belief. As such, it is an essential component of any complete theory of epistemic justification. ;I survey and evaluate all theories of the basing relation that I am aware of published between 1965 and 1995. (...) These include causal theories, , theories involving pseudo-overdetermination relations , theories involving what a person would appeal to in defense of her beliefs , and doxastic theories , involving an appeal to meta-beliefs. My discussion of these theories includes a detailed analysis of variations of Lehrer's case of the gypsy lawyer which, I show, can be reformulated to pose a decisive objection to causal theories, if not causal analyses, of the basing relation. ;Rejecting all published theories, I present a new kind of causal analysis of the basing relation which I call the causal-doxastic theory. This theory states that a belief is based on a reason if the reason bears an appropriate causal relation to the belief, or, it does not bear such a causal relation, but an appropriate meta-belief is present. A causal analysis of which meta-beliefs are appropriate is given, so as to count as inappropriate rationalizations, mistaken meta-beliefs, etc. In developing the causal-doxastic theory, I present a solution to the problem of deviant causal chains, a discussion of the causal sustaining of beliefs, an account of rejecting reasons, and a partial analysis of showing that one is justified. I then discuss implications of my theory regarding foundationalism, inference, basic and non-basic belief, holistic and linear coherentism, process reliabilism, internalism and externalism, and various closure principles. (shrink)