Inferential Internalists accept the Principle of Inferential Justification (PIJ), according to which one has justification for believing P on the basis of E only if one has justification for believing that E makes probable P. Richard Fumerton has defended PIJ by appeal to examples, and recently Adam Leite has argued that this principle is supported by considerations regarding the nature of responsible belief. In this paper, I defend a form of externalism against both arguments. This form of externalism recognizes what (...) I call the phenomenon of reflective defeat: if one is justified in not believing that E makes probable P, then this defeats whatever justification one has for believing P upon the basis of E. I argue that this modified version of externalism has the virtue of accommodating the intuitions that motivate internalism, without the cost of the vicious regress that makes internalism so unattractive. (shrink)

Knowledge can be transmitted by a valid deductive inference. If I know that p, and I know that if p then q, then I can infer that q, and I can thereby come to know that q. What feature of a valid deductive inference enables it to transmit knowledge? In some cases, it is a proof of validity that grounds the transmission of knowledge. If the subject can prove that her inference follows a valid rule, then her inference transmits knowledge. (...) However, this only pushes the question back to the inference that was made in this proof. What feature of that inference enables it to transmit knowledge? A vicious regress looms here. Every proof requires a valid inference, and every valid inference must follow at least one rule of inference. So every proof must follow at least one rule of inference. Therefore not every valid inference that transmits knowledge can acquire this power through a proof, on pain of vicious infinite regress. So it must be possible to transmit knowledge by making an inference that follows an underived rule. A deductive inference that follows an underived rule is what I will call a basic deductive inference. It must be possible to transmit knowledge by making a basic deductive inference. But how is this possible? What feature of a basic deductive inference gives it this power to transmit knowledge? (shrink)

Inconsistency-adaptive logics isolate the inconsistencies that are derivable from a premise set, and restrict the rules of Classical Logic only where inconsistencies are involved. From many inconsistent premise sets, disjunctions of contradictions are derivable no disjunct of which is itself derivable. Given such a disjunction, it is often justified to introduce new premises that state, with a certain degree of confidence, that some of the disjuncts are false. This is an important first step on the road to consistency: it narrows (...) down suspicion in inconsistent premise sets and hence locates the real problems among the possible ones. In this paper I present two approaches for handling such new premises in the context of the original premises. The first approach may apparently be combined with all paraconsistent logics. The second approach does not have the same generality, but is decidedly more elegant. (shrink)

The paper asks under what conditions deductive reasoning transmits justification from its premises to its conclusion. It argues that both standard externalist and standard internalist accounts of this phenomenon fail. The nature of this failure is taken to indicate the way forward: basic forms of deductive reasoning must justify by being instances of ‘blind but blameless’ reasoning. Finally, the paper explores the suggestion that an inferentialist account of the logical constants can help explain how such reasoning is possible.

in Philosophical Studies, Dec 2001, pp. 340-380.

Intuitions are often thought of as inputs to theoretical reasoning. For example, you might form a belief by taking an intuition at face value, or you might take your intuitions as starting points in the method of reflective equilibrium. The aim of this paper is to argue that in addition to these roles intuitions also play action-guiding roles. One form this takes is internal to theoretical reasoning: in addition to serving as inputs to theoretical reasoning, intuitions also guide it, enabling (...) the transmission of justification through inference. They play a similar role in guiding practical reasoning, enabling an action to be done for a reason. After making a case for assigning intuitions these additional action-guiding roles, I consider what it is in virtue of which an intuition can play such roles. I conclude by exploring the implications intuition’s playing these roles might have for two philosophical debates, one about the viability of moral intuitionism, and one about the epistemology of inference. (shrink)

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. (shrink)

We examine the role of working memory's central executive in the mental model explanation of propositional reasoning by using two working memory measures: the classical “reading span” test by Daneman and Carpenter (1980) and a new measure. This new “reasoning span” measure requires individuals to solve very simple anaphora problems, and store and remember the word solution in a growing series of inferential problems. We present one experiment in which we check the involvement of the central executive in conditional and (...) disjunctive inference tasks and compare predictions of the new reasoning span test with those of the classical reading span test. The results of the experiment confirm that reasoning responses, which according to mental model theory require high cognitive work, are predicted by working memory measures. Results also show that some reasoning responses are probably obtained by means of superficial biases or strategies that do not load working memory. The reasoning span test, which involves the central executive to a greater degree, predicts reasoning performance better than the reading span test. The significance and possibilities of the new measure in studying reasoning are discussed. (shrink)

I pursue an answer to the psychological question “what is it for S to presuppose that p?” I will not attempt a general answer. Rather, I will explore a particular kind of presuppositions that are constituted by the mental act of reasoning: Inferential presuppositions. Indeed, I will consider a specific kind of inferential presuppositions—one that is constituted by a specific reasoning competence: The univocality competence. Roughly, this is the competence that reliably governs the univocal thought-components’ operation as univocal in a (...) line of reasoning. I will argue that the exercise of this reasoning competence constitutes certain inferential presuppositions. More specifically, I outline a conception of an inferential presupposition as a non-attitudinal but genuinely psychological and rationally committing relation that holds between a reasoner and a proposition. Thus, inferential presuppositions may be distinguished from tacit or standing attitudes that function as premise-beliefs in reasoning. Likewise inferential presuppositions may be distinguished from other kinds of presuppositions. In conclusion, I note some features of inferential presuppositions that bear on the epistemology of inference. (shrink)

I Imperative Sentences It has often been taken for granted by logicians that there is a class of sentences which is the proper subject-matter of logic, ...

C hange in View offers an entirely original approach to the philosophical study of reasoning by identifying principles of reasoning with principles for revising one's beliefs and intentions and not with principles of logic. This crucial observation leads to a number of important and interesting consequences that impinge on psychology and artificial intelligence as well as on various branches of philosophy, from epistemology to ethics and action theory. Gilbert Harman is Professor of Philosophy at Princeton University. A Bradford Book.

Richard Fumerton’s “Principle of Inferential Justification” holds that, in order to be justified in believing P on the basis of E, one must be justified in believing that E makes P probable. I argue that the plausibility of this principle rests upon two kinds of mistakes: first, a level confusion; and second, a fallacy of misconditionalisation. Furthermore, Fumerton’s principle leads to skepticism about inferential justification, for which reason it should be rejected. Instead, the examples Fumerton uses to motivate his principle (...) can be accounted for using a different principle: in order for S to be justified in believing P on the basis of E, it must be true that E makes P probable. The latter principle can be independently motivated and does not lead to skepticism. (shrink)

Power has been studied in various guises in both the social cognition and the reasoning literatures. In this paper, three experiments are reported in which this factor was investigated in the domain of deontic thinking. Power of source of deontic statements was varied within several scenarios, and participants judged the degree to which they thought an injunction would be carried out. In the first experiment, permission statements were used, and it was found that, as predicted, power was positively related to (...) degree of endorsement of deontic conclusions across scenarios. In the second experiment, these findings were generalised across three further deontic domains (threat, warning, and promise) and two different syntactic forms (conjunctive and disjunctive). In the third experiment, the hypothesis that power effects were mediated by subjective judgements of conditional probability was investigated and confirmed. It is argued that these results favour theories that give a general role to probabilistic factors, rather than those based on domain-specific schemas. (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)

Is it coherent to suppose that in order to hold a belief responsibly, one must recognize something else as a reason for it? This paper addresses this question by focusing on so-called “Inferential Internalist” principles, that is principles of the following form: in order for one to have positive epistemic status Ø in virtue of believing P on the basis of R, one must believe that R evidentially supports P, and one must have positive epistemic status Ø in relation to (...) that latter belief as well. While such principles and their close relatives figure centrally in a wide variety of recent epistemological discussions, there is confusion in the literature about what, precisely, Inferential Internalism commits one to and whether it is so much as coherent. This paper (1) articulates a broader framework for understanding the notion of epistemic responsibility, (2) motivates Inferential Internalism on the basis of considerations about the basing relation, epistemic responsibility, and parallels with practical deliberation, (3) defends Inferential Internalism against charges of incoherence leveled by James Van Cleve and Paul Boghossian, and (4) shows that contrary to a currently widespread view, Inferential Internalism is coherent even if foundationalism and the a priori are rejected. The paper closes with a preliminary argument for an affirmative answer to the initiating question about the requirements of epistemic responsibility. (shrink)

This book examines two questions: Do people make use of abstract rules such as logical and statistical rules when making inferences in everyday life? Can such abstract rules be changed by training? Contrary to the spirit of reductionist theories from behaviorism to connectionism, there is ample evidence that people do make use of abstract rules of inference -- including rules of logic, statistics, causal deduction, and cost-benefit analysis. Such rules, moreover, are easily alterable by instruction as it occurs in classrooms (...) and in brief laboratory training sessions. The fact that purely formal training can alter them and that those taught in one content domain can "escape" to a quite different domain for which they are also highly applicable shows that the rules are highly abstract. The major implication for cognitive science is that people are capable of operating with abstract rules even for concrete, mundane tasks; therefore, any realistic model of human inferential capacity must reflect this fact. The major implication for education is that people can be far more broadly influenced by training than is generally supposed. At high levels of formality and abstraction, relatively brief training can alter the nature of problem-solving for an infinite number of content domains. (shrink)

There has long been a history of studies investigating how people (“ordinary people”) perform on tasks that involve deductive reasoning. The upshot of these studies is that people characteristically perform some deductive tasks well but others badly. For instance, studies show that people will typically perform MP (“modus ponens”: from ‘If A then B’ and ‘A’, infer ‘B’) and bi-conditional MP (from: ‘A if and only if B’ and ‘A’, infer ‘B’) correctly when invited to make the inference and additionally (...) can discover of their own accord when such inferences are appropriate. On the other hand, the same studies show that people typically perform MT (“modus tollens”: from ‘If A then B’ and ‘not-B’, infer ‘not-A’) and biconditional MT badly. They not only do not recognize when it is appropriate to draw such inferences, but also they will balk at doing them even when they are told that they can make it. Related to these shortcomings seems to be the inability of people to understand that contrapositives are equivalent (that ‘If A then B’ is equivalent to ‘If not-B then not-A’). [Studies of people’s deductive inference-drawing abilities have a long history, involving many studies in the early 20th century concerning Aristotelian syllogisms. But the current spate of studies draws much of its impetus from Wason (Wason, 1968; see also Wason & <span class='Hi'>Johnson</span>-Laird, 1972). ] The general conclusion seems to be that there are specific areas where “ordinary people” do not perform very logically. This conclusion will not come as a surprise to teachers of elementary logic, who have long thought that the majority of “ordinary people” are inherently illogical and need deep and forceful schooling in order to overcome this flaw. (shrink)

The aim of this paper is to investigate two related aspects of human reasoning, and use the results to construct an automated theorem prover for the predicate calculus that at least approximately models human reasoning. The result is a non-resolution theorem prover that does not use Skolemization. It involves two central ideas. One is the interest constraints that are of central importance in guiding human reasoning. The other is the notion of suppositional reasoning, wherein one makes a supposition, draws inferences (...) that depend upon that supposition, and then infers a conclusion that does not depend upon it. Suppositional reasoning is involved in the use of conditionals and reductio ad absurdum, and is central to human reasoning with quantifiers. The resulting theorem prover turns out to be surprisingly efficient, beating most resolution theorem provers on some hard problems. (shrink)

The mental model theory predicts that reasoners normally represent what is true, but not what is false. One consequence is that reasoners should make "illusory" inferences, which are compelling but invalid. Three experiments confirmed the existence of such illusions based on disjunctions of disjunctions. They also established a successful antidote to them: Reasoners are much less likely to succumb to illusions if the inferences concern disjunctions of physical objects (alternative newspaper advertisements) rather disjunctions of the truth values of assertions. The (...) results shed light both on the cause of the illusions and on the current controversy among different theories of reasoning. (shrink)

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. (shrink)

In virtue of what are we justified in employing the rule of inference Modus Ponens? One tempting approach to answering this question is to claim that we are justified in employing Modus Ponens purely in virtue of facts concerning meaning or concept-possession. In this paper, we argue that such meaning-based accounts cannot be accepted as the fundamental account of our justification.

One of Laurence BonJour’s main arguments for the existence of the a priori is an argument that a priori justification is indispensable for making inferences from experience to conclusions that go beyond experience. This argument has recently come under heavy fire from Albert Casullo, who has dubbed BonJour’s argument, “The Generality Argument.” In this paper I (i) defend the Generality Argument against Casullo’s criticisms, and (ii) develop a new, more plausible, version of the Generality Argument in response to some other (...) objections of my own. Two of these objections stem out of BonJour’s failing to fully consider the importance of the distinction between being justified in believing that an inference is good and being justified in making an inference. The final version of the argument that I develop sees the Generality Argument as one part of a cumulative case argument for the existence of a priori justification, rather than as a stand-alone knock-down argument. (shrink)

Does inferential justification require the subject to be aware that her premises support her conclusion? Externalists tend to answer “no” and internalists tend to answer “yes”. In fact, internalists often hold the strong higher-level requirement that an argument justifies its conclusion only if the subject justifiably believes that her premises support her conclusion. I argue for a middle ground. Against most externalists, I argue that inferential justification requires that one be aware that her premises support her conclusion. Against many internalists, (...) I argue that this higher-level awareness needn’t be doxastic or justified. I also argue that the required higher-level awareness needn’t be caused in some appropriate way, e.g. by a reliable or properly functioning faculty. I suspect that this weaker higher-level requirement is overlooked because, at first glance, it seems absurd to allow nondoxastic, unjustified, and unreliably-caused higher-level awareness to contribute to inferential justification. One of the central goals of this paper is to explain how such weak awareness can make an essential contribution to inferential justification. (shrink)

The inferentialist account of the a priori says that basic logical beliefs can be justified by way of rule circular inference. I argue that this account of the a priori fails to skirt the charge of begging the question, that the reasons offered in support of it are weak and that it makes justifying logical beliefs too easy. I also argue that recent modifications to inferentialism spell doom for it as a general theory of a priori justification.

Biological and Cultural Bases of Human Inference addresses the interface between social science and cognitive science. In this volume, Viale and colleagues explore which human social cognitive powers evolve naturally and which are influenced by culture. Updating the debate between innatism and culturalism regarding human cognitive abilities, this book represents a much-needed articulation of these diverse bases of cognition. Chapters throughout the book provide social science and philosophical reflections, in addition to the perspective of evolutionary theory and the central assumptions (...) of cognitive science. The overall approach of the text is based on three complementary levels: adult performance, cognitive development, and cultural history and prehistory. Scholars from several disciplines contribute to this volume, including researchers in cognitive, developmental, social and evolutionary psychology, neuropsychology, cognitive anthropology, epistemology, and philosophy of mind. This contemporary, important collection appeals to researchers in the fields of cognitive, social, developmental, and evolutionary psychology and will prove valuable to researchers in the decision sciences. (shrink)

What is the connection between justification and the kind of consequence relations that are studied by logic? In this essay, I shall try to provide an answer, by proposing a general conception of the kind of inference that counts as justified or rational.

Both these ideas are intuitively plausible: rationality has an external aim, such as forming a true belief or good decision; and the rationality of a belief or decision is determined purely by facts about the thinker's internal mental states. Unlike earlier conceptions, the conception of rationality presented here explains why these ideas are both true. Rational beliefs and decisions, it is argued, are those that are formed through the thinker's following `rules of rationality'. Some rules count as rules of rationality (...) because it is rational to believe-through following other rules-that those rules are reliable. But there must also be certain basic rules, which are a priori, or `built into' our basic cognitive capacities. That these rules are a priori is a purely internal matter; and in following these rules the thinker has done all that could reasonably be expected to achieve the external aim of forming a true belief or good decision. (shrink)

[Paul Boghossian] The paper asks under what conditions deductive reasoning transmits justification from its premises to its conclusion. It argues that both standard externalist and standard internalist accounts of this phenomenon fail. The nature of this failure is taken to indicate the way forward: basic forms of deductive reasoning must justify by being instances of 'blind but blameless' reasoning. Finally, the paper explores the suggestion that an inferentialist account of the logical constants can help explain how such reasoning is possible. (...) /// [Timothy Williamson] The paper challenges the inferentialist account of concept possession that Paul Boghossian takes as a premise in his account of the transmission of justification by deductive reasoning in his paper 'Blind Reasoning'. Unorthodox speakers who reject the inferences in an alleged possession condition can still have the concept by understanding a word for it. In that sense, the inferences are not analytic. Inferentialist accounts of logical constants, theoretical terms (using the Ramsey-Carnap-Lewis method) and pejorative expressions such as 'Boche' are examined and rejected. It is suggested that epistemological questions cannot be reduced to questions in the theory of thought and meaning. (shrink)