This dissertation is about a priori justification and its relationship to experiential evidence. I begin with the assumption that a priori justification is justification that is independent of experience. It has been argued that putative examples of a priori justification are implausible because they are not, in any significant sense, independent of experience. My two central claims are that (a) a subject is plausibly justified a priori in believing a proposition only if (...) the belief is not revisable on empirical grounds, which I will call the empirical unrevisability thesis; and (b) moderate rationalists can resist four empirical challenges considered by many to be decisive against the empirical unrevisability thesis. I begin by developing an account of experiential evidence that is neutral between rationalists and empiricists in order to make clear the distinction between a priori and a posteriori justification. I then argue that a moderate rationalist account of a priori justification is plausible only if the beliefs justified a priori are empirically unrevisable in a qualified sense. I then argue that four classical objections that putative cases of a priori justification are not independent of experience fail, namely, that they are revisable by some instances of contrary testimony, by mistakes in long proofs and memory, that a paradigm example of a priori knowledge was overturned by new evidence in physics, and that psychological data undermines the reliability of sources of a priori justification. I conclude that there is only one potentially threatening case, derived from neurological malfunction, and I leave the solution to this case to future research. (shrink)

The major divide in contemporary epistemology is between those who embrace and those who reject a priori knowledge. Albert Casullo provides a systematic treatment of the primary epistemological issues associated with the controversy. By freeing the a priori from traditional assumptions about the nature of knowledge and justification, he offers a novel approach to resolving these issues which assigns a prominent role to empirical evidence. He concludes by arguing that traditional approaches to the a priori, which (...) focus primarily on the concepts of necessity and analyticity, are misguided. (shrink)

Broadly speaking, a naturalistic approach to epistemology seeks to explain human knowledge – and justification in particular – as a phenomenon in the natural world, in keeping with the tenets of naturalism. Naturalism is typically defined, in part, by a commitment to scientific method as the only legitimate means of attaining knowledge of the natural world. Naturalism is often thought to entail empiricism by virtue of this methodological commitment. However, scientific methods themselves may incorporate a priori elements, so (...) empiricism does not follow from the methodological commitments of naturalism alone. And given a suitably-naturalistic conception of the a priori, a priori forms of justification may be compatible with naturalism generally. A priori justification is, in principle, compatible with naturalism – and hence naturalistic epistemologies – if the a priori is understood in a way that is free of some of the inessential properties that have been associated with the concept. I argue that some of the more prominent strategies for accommodating normative notions within a naturalistic framework allow for the possibility of a priori justification. These include reliabilism, instrumental rationality, and nonfactualism about justification. A priori justification thus need not be seen as standing in opposition to all naturalistic epistemologies. It is only with nonnormative naturalistic epistemologies that a priori justification per se is incompatible, and this only because the notion of justification itself has no role to play within a nonnormative approach to epistemology. (shrink)

This paper argues there are crucial points in Nietzsche’s texts where he offers a priori epistemic justification for views he believes are correct. My reading contrasts with the dominant view that Nietzsche’s philosophical naturalism is incompatible with a priori justification. My aim is to develop Nietzsche’s brand of a priori justification, show that he employs this account of justification in the texts, and suggest how it might be compatible with naturalism.

In recent years many influential philosophers have advocated that philosophy is an a priori science. Yet very few epistemology textbooks discuss a priori knowledge at any length, focusing instead on empirical knowledge and empirical justification. As a priori knowledge has moved centre stage, the literature remains either too technical or too out of date to make up a reasonable component of an undergraduate course. Edwin Mares book aims to rectify this. This book seeks to make accessible (...) to students the standard topics and current debates within a priori knowledge, including necessity and certainty, rationalism, empiricism and analyticity, Quine's attack on the a priori, Kantianism, Aristotelianism, mathematical knowledge, moral knowledge, logical knowledge and philosophical knowledge. (shrink)

Joshua Thurow offers a defence of the claim that if a belief is defeasible by non-experiential evidence then it is defeasible by experiential evidence. He responds to an objection which I make against this claim, and offers two arguments in support of his own position. I show that Thurow's response misconstrues my objection, and that his supporting arguments fall short of their goal.

Laurence BonJour’s In Defense of Pure Reason is rich and challenging. It offers a tightly integrated attack on empiricism and defense of rationalism. The tight texture of argument makes it difficult to isolate and assess specific aspects of the book in a brief discussion. My goal is to examine the role of experience in BonJour’s conception of a priori justification.

A review of Albert Casullo's "A Priori Justification" (Oxford University Press).

John Bengson holds that an intellectual seeming is sufficient for a priori justification, whereas Elijah Chudnoff disagrees and holds that a priori justification also requires an intuitive awareness of the abstract entities that are the subject matter of the proposition to be justified. I distinguish between substantive and non-substantive a priori claims about the world, and argue that Chudnoff is correct about the justification required for the former kind of claim, and Bengson is correct (...) about the justification required for the latter. In brief, substantive a priori claims about the world require for justification a process of reflection that takes as input states of awareness of the abstract entities in the world that are the subject matter of the claim, and yields as output an intellectual seeming that the claim is true. Whereas non-substantive a priori claims about the world (merely conceptual claims) can be justified merely by an intellectual seeming that the claim is true, so long as the seeming is a manifestation of conceptual competence. (shrink)

In his recent book Albert Casullo rejects the claim that if a belief is defeasible by non-experiential evidence then it is defeasible by experiential evidence. This claim is a crucial premise in a simple argument for the experiential defeasibility of a priori justification. I defend the premise against Casullo's objection, the main problem with which is that he does not take into account the evidential role of multiple corroborating sources of testimony. I conclude that the crucial premise is (...) true and that the simple argument is sound; thus many of our a priori justified beliefs are experientially defeasible. (shrink)

Kant famously argued that, from experience, we can only learn how something actually is, but not that it must be so. In this paper, I defend an improved version of Kant's argument for the existence of a priori knowledge, the Modal Argument , against recent objections by Casullo and Kitcher. For the sake of the argument, I concede Casullo's claim that we may know certain counterfactuals in an empirical way and thereby gain epistemic access to some nearby, nomologically possible (...) worlds. But I maintain that our beliefs about metaphysical necessities still cannot be justified empirically. Furthermore, I reject Casullo's deflationary thesis about the significance of such justification. Kitcher's most troublesome objection is that we can gain any modal justification whatsoever through testimony , i.e. in an experiential way. This can be countered by distinguishing between productive sources of justification, like perception, and merely reproductive sources, like testimony. Thus, some productive a priori source will always be needed somewhere. (shrink)

This book is concerned with the alleged capacity of the human mind to arrive at beliefs and knowledge about the world on the basis of pure reason without any dependence on sensory experience. Most recent philosophers reject the view and argue that all substantive knowledge must be sensory in origin. Laurence BonJour provocatively reopens the debate by presenting the most comprehensive exposition and defence of the rationalist view that a priori insight is a genuine basis for knowledge. This important (...) book will be at the centre of debate about the theory of knowledge for many years to come. (shrink)

Laurence BonJour's (1985) coherence theory of empirical knowledge relies heavily on a traditional foundationalist theory of a priori knowledge. He argues that a foundationalist, rationalist theory of a priori justification is indispensable for a coherence theory. BonJour (1998) continues this theme, arguing that a traditional account of a priori justification is indispensable for the justification of putative a priori truths, the justification of any non-observational belief and the justification of reasoning itself. (...) While BonJour's indispensability arguments have received some critical discussion (Gendler 2001; Harman 2001; Beebe 2008), no one has investigated the indispensability arguments from a coherentist perspective. This perspective offers a fruitful take on BonJour's arguments, because he does not appreciate the depth of the coherentist alternative to the traditional empiricist-rationalist debate. This is surprising on account of BonJour's previous defense of coherentism. Two significant conclusions emerge: first, BonJour's indispensability arguments beg central questions about an explanationist form of coherentism; second, BonJour's original defense of coherentism took on board certain assumptions that inevitably led to the demise of his form of coherentism. The positive conclusion of this article is that explanatory coherentism is more coherent than BonJour's indispensability arguments assume, and more coherent than BonJour's earlier coherentist epistemology. (shrink)

Radical empiricism is the view that experience is the only source of knowledge. Hence, radical empiricism denies the existence of a priori knowledge. Its most famous proponents are John Stuart Mill and W. V. Quine. Although both reject a priori knowledge, they offer different empiricist accounts of the knowledge alleged by their opponents to be a priori. My primary concern in this paper is not with the cogency of their positive accounts. My focus is their arguments against (...) a priori knowledge. My goal is to establish that although they offer very different arguments against the existence of a priori knowledge, each of their arguments suffers from a common defect. They both fail to appreciate the phenomenon of epistemic overdetermination and its role in the theory of knowledge. (shrink)

In my book In Defense of Pure Reason, I offer an extended defense of the idea of a priori justification and, more specifically, of a rationalist conception of such justification: one according to which rational insight or intuition provides genuine justification for claims that need not be merely definitional or tautological in character. In the relatively brief space available to me on the present occasion, I want to present and defend, necessarily in rather broad strokes, four (...) of the most central claims that are discussed at much greater length in that book. I will say the most about the first of these theses, somewhat less about the second and third, and only a very little about the fourth. (shrink)

There are propositions that upon understanding them it seems that one can “just see” that they are necessary or impossible. A commonly discussed example is the claim that it is not possible for an object to be red and green all over at the same time. My purpose in this paper is to account for how it is that such beliefs are justified. I begin by criticizing a suggestion defended lately by Laurence BonJour and others. BonJour argues that because these (...) beliefs are necessarily true external factors are irrelevant to their epistemic status. This is how BonJour can defend a foundationalist account of the a priori while at the same time attacking foundationalism with respect to empirical knowledge. I argue that this view of the a priori is mistaken. External factors are relevant even in the case of those a priori beliefs it seems we can just see to be true. I defend an alternative account of the justification of such beliefs. I argue that these beliefs may be justified in virtue of their being the products of a basic belief-forming mechanism one has no reason to distrust. In particular, I argue that this approach can be employed to account for the non-inferential justification of a priori beliefs without falling prey to the line of objections BonJour lodges against other forms of foundationalism. (shrink)

Laurence BonJour’s In Defense of Pure Reason is rich and challenging. It offers a tightly integrated attack on empiricism and defense of rationalism. The tight texture of argument makes it difficult to isolate and assess specific aspects of the book in a brief discussion. My goal is to examine the role of experience in BonJour’s conception of a priori justification.

This book is concerned with the alleged capacity of the human mind to arrive at beliefs and knowledge about the world on the basis of pure reason without any dependence on sensory experience. Most recent philosophers reject the view and argue that all substantive knowledge must be sensory in origin. Laurence BonJour provocatively reopens the debate by presenting the most comprehensive exposition and defence of the rationalist view that a priori insight is a genuine basis for knowledge. This important (...) book will be at the centre of debate about the theory of knowledge for many years to come. (shrink)

In a recent and interesting paper “Experientially Defeasible A Priori Justification,” Joshua Thurow argues that many a priori justified beliefs are defeasible by experience. The argument takes the form of an objection against Albert Casullo’s recent book, A Priori Justification, where Casullo, according to Thurow, denies that if a justified belief is non-experientially defeasible, then that belief is also experientially defeasible. This paper critically examines Thurow’s two arguments in the first two sections I–II. In the (...) last section, III, an alternative line of argument for Thurow’s thesis is suggested that employs other parts of the framework that Casullo provides—especially the thesis of overdetermination of justification. It will be argued that the prospects for this suggestion are brighter than for bothof Thurow’s arguments. (shrink)

The past twenty-five years have seen a major renewal of interest in the topic of a priori knowledge. In the sixteen essays collected here, which span this entire period, philosopher Albert Casullo documents the complex set of issues motivating the renewed interest, identifies the central epistemological questions, and provides the leading ideas of a unified response to them.

At any given time, an individual has certain beliefs and certain procedures or methods for modifying those beliefs. In The Realm of Reason, as in his previous book, Being Known (1999), Christopher Peacocke is concerned with the elusive question of what it is for someone to be “entitled” to a given belief or procedure.1..

There are propositions that upon understanding them it seems that one can “just see” that they are necessary or impossible. A commonly discussed example is the claim that it is not possible for an object to be red and green all over at the same time. My purpose in this paper is to account for how it is that such beliefs are justified. I begin by criticizing a suggestion defended lately by Laurence BonJour and others. BonJour argues that because these (...) beliefs are necessarily true external factors are irrelevant to their epistemic status. This is how BonJour can defend a foundationalist account of the a priori while at the same time attacking foundationalism with respect to empirical knowledge. I argue that this view of the a priori is mistaken. External factors are relevant even in the case of those a priori beliefs it seems we can just see to be true. I defend an alternative account of the justification of such beliefs. I argue that these beliefs may be justified in virtue of their being the products of a basic belief-forming mechanism one has no reason to distrust. In particular, I argue that this approach can be employed to account for the non-inferential justification of a priori beliefs without falling prey to the line of objections BonJour lodges against other forms of foundationalism. (shrink)

The past twenty-five years have seen a major renewal of interest in the topic of a priori knowledge. In the sixteen essays collected here, which span this entire period, philosopher Albert Casullo documents the complex set of issues motivating the renewed interest, identifies the central epistemological questions, and provides the leading ideas of a unified response to them.

Laurence BonJour divides approaches to a priori justification into three kinds. Quine’s radical empiricism denies the existence of any special category of a priori justification; moderate empiricism attempts to explain a priori justification in terms of something like knowledge of meaning or grasp of concepts; and rationalism postulates an irreducible ‘rational insight’ into the nature of reality. The positions therefore form a familiar trio of eliminativism, reductionism and anti-reductionism concerning a priori justification. (...) BonJour’s interesting and (in the present philosophical climate) unusual project is to defend rationalism, the anti-reductionist position. Rationalism says that we have an ability to ‘directly or intuitively see or grasp or apprehend … a necessary fact about the nature or structure of reality’ (pp. 15-16). ‘An apparent rational insight,’ he says, ‘purports to be nothing less than a direct insight into the necessary character of reality’ (p. 107). Two clarifications will help to mark out the distinctive character of this view: first, that rational insight is fallible; and second, that although BonJour carefully distinguishes the concepts of necessity and apriority, he none the less claims that rational insight yields a priori knowledge of necessary truths only. On his view, the contingent a priori does not exist, although empirical necessities do... (shrink)

There are four approaches to analyzing the concept of a priori knowledge. The primary target of the reductive approach is the concept of a priori justification. The primary target of the nonreductive approach is the concept of a priori knowledge. There are two approaches to analyzing each primary target. A theory-neutral approach provides an analysis that does not presuppose any general theory of knowledge or justification. A theory-laden approach provides an analysis that does presuppose some (...) general theory of knowledge or justification (call it the background theory). Those who embrace a theory-laden analysis incur a special burden: they must separate the features of their analysis that are constitutive of the a priori from those that are constitutive of the background theory. My goal is to illustrate how the failure to separate these features leads to erroneous conclusions about the nature of a priori knowledge. (shrink)

In this paper I argue that Michael Friedman's conception of the contitutive a priori faces two serious problems. These two problems show that the view collapses into a form of conventionalism.

The distinction between a priori and a posteriori knowledge has been the subject of an enormous amount of discussion, but the literature is biased against recognizing the intimate relationship between these forms of knowledge. For instance, it seems to be almost impossible to find a sample of pure a priori or a posteriori knowledge. In this paper, it will be suggested that distinguishing between a priori and a posteriori is more problematic than is often suggested, and that (...) a priori and a posteriori resources are in fact used in parallel. We will define this relationship between a priori and a posteriori knowledge as the bootstrapping relationship. As we will see, this relationship gives us reasons to seek for an altogether novel definition of a priori and a posteriori knowledge. Specifically, we will have to analyse the relationship between a priori knowledge and a priori reasoning , and it will be suggested that the latter serves as a more promising starting point for the analysis of aprioricity. We will also analyse a number of examples from the natural sciences and consider the role of a priori reasoning in these examples. The focus of this paper is the analysis of the concepts of a priori and a posteriori knowledge rather than the epistemic domain of a posteriori and a priori justification. (shrink)

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)