Kenneth R. Westphal

This collection of original essays aims to reinvigorate the debate surrounding philosophical realism in relation to philosophy of science, pragmatism, epistemology, and theory of perception. Questions concerning realism are as current and as ancient as philosophy itself; this volume explores relations between different positions designated as ‘realism’ by examining specific cases in point, drawn from a broad range of systematic problems and historical views, from ancient Greek philosophy through the present. The first section examines the context of the project; contributions systematically engage the historical background of philosophical realism, re-examining key works of Aristotle, Descartes, Quine, and others. The following two sections epitomize the central tension within current debates: scientific realism and pragmatism. These contributions address contemporary questions of scientific realism and the reality of the objects of science, and consider whether, how or the extent to which realism and pragmatism are compatible. With an editorial introduction by Kenneth R. Westphal, these fourteen original essays provide wide-ranging, salient insights into the status of realism today.

Gauthier’s contractarianism begins with an idea of a rational deliberator but ‘finds no basis for postulating a moral need for the justification of one’s actions to others. The role of agreement is to address each person’s demand that the constraints of society be justified to him, not a concern that he justify himself to his fellows’ (Gauther 1997, 134–5). He contrasts his view with Scanlon’s contractualism, according to which agreement with others is the core of morality and each agent has the burden of justifying his or her actions to others. Both of their views count as ‘constructivist’ because they reject moral realism and hold that normativity is a function of what we do, either individually or collectively. Kant’s Rechtslehre is neutral regarding moral realism and yet constructivist about moral norms. However, the relevant acts basic to Gauthier’s and Scanlon’s views concern voluntary agreements we make. Using agreement to establish basic norms faces some serious difficulties. Kant’s Rechtslehre avoids these problems by showing how basic social norms can be identified and justified independently of voluntary agreement. Moreover, it does so in a way that shows that an individual’s justification of his or her acts to others and the justification of the acts of others to any individual are inseparable aspects of one and the same justificatory reasons in which voluntary agreement plays no role.

This article examines how Quine and Sellars develop informatively contrasting responses to a fundamental tension in Carnap’s semantics ca. 1950. Quine’s philosophy could well be styled ‘Essays in Radical Empiricism’; his assay of radical empiricism is invaluable for what it reveals about the inherent limits of empiricism. Careful examination shows that Quine’s criticism of Carnap’s semantics in ‘Two Dogmas of Empiricism’ fails, that at its core Quine’s semantics is for two key reasons incoherent and that his hallmark Thesis of Extensionalism is untenable. The tension in Carnap’s semantics together with Quine’s exposure of the severe limits of radical empiricism illuminate central features of Sellars’s philosophy: the fully general form of the myth of givenness, together with Sellars’s alternative Kantian characterisation of understanding; the full significance of Carnap’s distinction between conceptual analysis and conceptual explication, and its important methodological implications; the specifically pragmatic character of Sellars’s realism; and Sellars’s methodological reasons for holding that philosophy must be systematic and that systematic philosophy must be deeply historically and textually informed. This paper thus re-examines this recent episode of philosophical history for its philosophical benefits and systematic insights

Kant famously declares that “although all our cognition commences with experience, … it does not on that account all arise from experience”. This marks Kant’s disagreement with empiricism, and his contention that human knowledge and experience require both sensation and the use of certain a priori concepts, the Categories. However, this is only the surface of Kant’s much deeper, though neglected view about the nature of reason and judgment. Kant holds that even our a priori concepts are acquired, not from sensation, but “originally,” because our mind has a fundamental capacity to judge that, upon sensory stimulation, generates the Categories through its basic logical functions of judgment. This “epigenesis” of reason and our fundamental capacity to judge that drives it is the topic of Longuenesse’s fascinating book, and the source of her title.

Hume and contemporary Humeans contend that moral sentiments form the sole and sufficient basis of moral judgments. This thesis is criticised by appeal to Hume’s theory of justice, which shows that basic principles of justice are required to form and to maintain society, which is indispensable to human life, and that acting according to, or violating, these principles is right, or wrong, regardless of anyone’s sentiments, motives or character. Furthermore, Hume’s theory of justice shows how the principles of justice are artificial without being arbitrary. In this regard, Hume’s theory belongs to the unjustly neglected modern natural law tradition. Some key merits of this strand in Hume’s theory are explicated by linking it to Kant’s constructivist method of identifying and justifying practical principles (à la O’Neill), and by showing how and why Hegel adopted and further developed Kant’s constructivism by re-integrating it with Hume’s central natural law concern with our actual social practices. (Slightly revised English translation by the author of „Von der Konvention zur Sittlichkeit. Humes Begründung einer Rechtsethik aus nach-Kantischer Perspektive“, on which see below.)

This article shows that Hegel’s analysis of ‘Perception’ (PhdG, ch. 2) is a critique of Hume’s analysis, ‘Of Scepticism with regard to the senses’ (Treatise, I.iv §2). To extend his concept-empiricism to handle the non-logical concept of the identity of a perceptible thing, Hume must appeal to several psychological ‘propensities’ to generate, in effect, a priori concepts; he must confront a ‘contradiction’ in the concept of the identity of a perceptible thing; and he must regard this concept as a ‘fiction’. Hegel reexamines Hume’s account to show that the concept of the identity of a perceptible thing is non-logical and cannot be defined in accord with concept-empiricism. This important point supports Hegel’s concept-pragmatism. This point is also important in connection with the quite general problem of how we bring various sensations together into the perception of any one object. (English translation by the author of „Vom Skeptizismus in Bezug auf die Sinne oder das Ding und die Täuschung“.)

The idea that noumena or things in themselves causally affect our sensibility, and thus provide us with sensations, has been rejected on two basic grounds: It is unintelligible because distinguishes between appearance and reality in such a way that things cannot in principle appear as they really are, and it requires applying the concept of causality trans-phenomenally, contra Kant’s Schematism. I argue that noumenal causality is intelligible and is required out of fidelity to Kant’s texts and doctrines. Kant’s theory of meaning and his transcendental reflection on sensibility show how Kant legitimately can speak about, and determine that, our passive sensibility must be causally affected by noumena. Kant’s analysis of agency shows that Kant’s practical philosophy requires noumenal causality, both from a first- and from a third-person perspective. These points ground my criticisms of Buchdahl and Allison’s view of affection, and Strawson and Sandberg’s view of meaning.

Few if any of Kant’s critics were more trenchant than Hegel. Here I reconstruct some objections Hegel makes to Kant in a text that has received insufficient attention, the chapter titled ‘the Moral World View’ in the Phenomenology of Spirit. I show that Kant holds virtually all the tenets Hegel ascribes to ‘the moral world view’. I concentrate on five of Hegel’s main objections to Kant’s practical metaphysics. First, Kant’s problem of coordinating happiness with virtue (as worthiness to be happy) is contrived. Kant denies that there is any inherent connection between acting rightly and being happy, but his denial depends on his defining happiness in terms of satisfying inclinations, rather than in terms of achieving ends in general. Second, Kant’s view of moral motivation is contrived; he ultimately admits that we cannot resolve to act without taking inclinations into account. (We cannot resolve to act apart from the matter of our maxim.) Third, Kant’s idea about perfecting our virtue in an infinite progress is incoherent. Kant defines virtue, and evidence of virtue, in terms of overcoming inclinations. Inclinations die with the body. Therefore there can be neither virtue nor evidence of virtue after death. Fourth, Kant’s view of the autonomy of moral agency is inconsistent with viewing the moral law as a divine command. Fifth, Kant’s moral principles cannot be put into practice in concrete circumstances because he supplies inadequate guidance for classifying acts. I conclude that Hegel’s objections to Kant’s practical metaphysics are sound, and I show that the problems Hegel raised against Kant’s account of autonomy and moral motivation are still current, since they have not been resolved, e.g., by Onora O’Neill’s Constructions of Reason

Argues inter alia that Kant and Hegel identified necessary conditions for the possibility of singular cognitive reference that incorporate avant la lettre Evans’ (1975) analysis of identity and predication, that Kant’s and Hegel’s semantics of singular cognitive reference are crucial to McDowell’s account of singular thoughts, and that McDowell has neglected (to the detriment of his own view) these conditions and their central roles in Kant’s and in Hegel’s theories of knowledge. > Reprinted in: J. Lindgaard, ed., John McDowell: Experience, Norm and Nature (Oxford: Blackwell, 2008d), 124–151.

This article reconstructs Hegel’s chapter “Sense Certainty” (Phenomenology of Spirit, chap. 1) in detail in its historical and philosophical context. Hegel’s chapter develops a sound internal critique of naive realism that shows that sensation is necessary but not sufficient for knowledge of sensed particulars. Cognitive reference to particulars also requires using a priori conceptions of space, spaces, time, times, self, and individuation. Several standard objections to and misinterpretations of Hegel’s chapter are rebutted. Hegel’s protosemantics is shown to accord in important regards with Gareth Evans’ view in “Identity and Predication.”

This paper details the key steps in Kant’s transcendental proof that we perceive, not merely imagine, physical objects. These steps begin with Kant’s method (§II) and highlight the spatio-temporal character of our representational capacities (§III), Kant’s two transcendental proofs of mental content externalism (§IV), his proof that we can only make causal judgments about spatial substances (§§V, VI), the transcendental conditions of our self-ascription of experiences (§VII), Kant’s semantics of singular cognitive reference (§VIII), perceptual synthesis (§IX), Kant’s justificatory fallibilism (§X), and the cognitive transcendence of global perceptual hypotheses (§XI). The proof outlined here differs markedly from ‘analytic transcendental arguments’ that focus selectively on Kant’s ‘Refutation of Idealism’ and portions of the ‘Transcendental Deduction of the Pure Concepts of the Understanding’. Understood as presented here, Kant’s epistemology is directly relevant to contemporary philosophical issues

Henry Allison criticizes and rejects naturalism because the idea of freedom is constitutive of rational spontaneity, which alone enables and entitles us to judge or to act rationally, and only transcendental idealism can justify our acting under the idea of freedom. Allison’s critique of naturalism is unclear because his reasons for claiming that free rational spontaneity requires transcendental idealism are inadequate and because his characterization of Kant’s idealism is ambiguous. Recognizing this reinforces the importance of the question of whether only transcendental idealism “can ground the right to the conceptual space” that we occupy when thinking spontaneously or acting under the idea of freedom. Only with a clear answer to this question can Kant’s idea of freedom provide a basis for assessing today’s naturalist orthodoxy.

The tension between Kant’s egalitarian conception of persons as ends in themselves and his rejection of the right of revolution has been widely discussed. The crucial issue is more fundamental: Is Kant’s defense of absolute obedience consistent with his own principle of legitimate law, that legitimate law is compatible with the Categorical Imperative? Resolving this apparent inconsistency resolves the subsidiary inconsistencies that have been debated in the literature. I argue that Kant’s legal principles contain two distinct grounds of obligation to obey political authority. One lies in his metaphysical principles of law, according to which there is only a duty to obey legitimate law or fully legitimate authorities. Another lies in his moral-pragmatic principles. He believes that membership in the state helps improve one’s character by counter-balancing one’s immoral inclinations. This is his ultimate ground for obedience to de facto, imperfectly legitimate states. On this ground, the duty to obey an actual state is conditional. Kant’s strong statements about the duty to obey actual states is explained by the ease with which he thinks the relevant condition is met by extant states. The apparent ambiguities in his discussion of obedience point to some important philosophical and historical shortcomings of his analysis of the division of govemmental powers and of judicial competence which hamper his analysis of the duty to obey the state.

Kant’s ‘Refutation of Idealism’ plainly has an anti-Cartesian conclusion: ‘inner experience in general is only possible through outer experience in general’ (B278). Due to wide-spread preoccupation with Cartesian skepticism, and to the anti-naturalism of early analytic philosophy, most of Kant’s recent commentators have sought to find a purely conceptual, ‘analytic’ argument in Kant’s Refutation of Idealism – and then have dismissed Kant when no such plausible argument can be reconstructed from his text. Kant’s argument supposedly cannot eliminate all relevant alternatives, and so cannot justify its strong modal claims. Kant based his arguments on an inventory of our basic cognitive capacities to employ our forms of intuition and our forms of judgment. Kant provides a variety of considerations and arguments to determine what our cognitive capacities are. This involves ‘transcendental reflection’, which Kant held is absolutely crucial for judging matters a priori (A263/B319). I argue that there is a level of philosophical reflection on our own cognitive capabilities and their preconditions that is significantly richer than has been noticed by recent commentators, and that is a precondition of Kant’s transcendental reflection proper. I explicate certain thought experiments Kant proposes in order for us to recognize some our basic, characteristic cognitive capabilities, and the limits and requirements they entail for the nature and objects of human knowledge. These thought experiments involve a kind of reflection on who we as cognizant subjects are, on what our basic cognitive capabilities are. Engaging in this kind of reflection reveals that Kant’s transcendental arguments are significantly stronger and more persuasive than has been recognized in recent commentary.

The term ‘realism’ and its contrasting terms have various related senses, although often they occlude as much as they illuminate, especially if ontological and epistemological issues and their tenable combinations are insufficiently clarified. For example, in 1807 the infamous ‘idealist’ Hegel argued cogently that any tenable philosophical theory of knowledge must take the natural and social sciences into very close consideration, which he himself did. Here I argue that Hegel ably and insightfully defends Newton’s causal realism about gravitational force, in part by exposing a fatal equivocation in the traditional concept of substance, by criticizing some still-standard empiricist misconceptions of force, by emphasizing the role of explanatory integration in Newtonian mechanics, and by using his powerful semantics of singular, specifically cognitive reference to justify fallibilism regarding empirical justification, together with the semantic core of Newton’s Rule Four of (experimental) Philosophy—in a way that highlights a key fallacy in many arguments against realism, both in epistemology and within philosophy of science.

In 1792 and 1798 Kant noticed two basic problems with hisMetaphysical Foundations of Natural Science (MAdN) which opened a crucial gap in the Critical system as a whole. Why is theMAdN so important? I show that the Analogies of Experience form an integrated proof of transeunt causality. This is central to Kant's answer to Hume. This proof requires explicating the empirical concept of matter as the moveable in space, it requires the specifically metaphysical principle that every physical event has an external cause, and it requires a metaphysical principle regarding the individuation of spatio-temporal things. These three doctrines are not defended in the firstCritique, but only in theMAdN. Kant's transcendental analysis of the conditions of experience thus requires the special metaphysics of theMAdN. This marks an important shift in Kant's view of the metaphysical basis of the transcendental philosophy.

For many reasons mainstream Hegel scholarship has disregarded Hegel's interests in epistemology, hence also his response to scepticism. From the points of view of defenders and critics alike, it seems that 'Hegel' and 'epistemology' have nothing to do with one another. Despite this widespread conviction, Hegel was a very sophisticated epistemologist whose views merit contemporary interest. This article highlights several key features and innovations of Hegel's epistemology-including his anti-Cartesianism, fallibilism, realism (sic) and externalism both about mental content and about justification-by considering his systematic responses to Pyrrhonian, Humean, Cartesian and Kantian scepticism

This book is the first detailed study of Kant's method of 'transcendental reflection' and its use in the Critique of Pure Reason to identify our basic human cognitive capacities, and to justify Kant's transcendental proofs of the necessary a priori conditions for the possibility of self-conscious human experience. Kenneth Westphal, in a closely argued internal critique of Kant's analysis, shows that if we take Kant's project seriously in its own terms, the result is not transcendental idealism but realism regarding physical objects. Westphal attends to neglected topics - Kant's analyses of the transcendental affinity of the sensory manifold, the 'lifelessness of matter', fallibilism, the semantics of cognitive reference, four externalist aspects of Kant's views, and the importance of Kant's Metaphysical Foundations for the Critique of Pure Reason - that illuminate Kant's enterprise in new and valuable ways. His book will appeal to all who are interested in Kant's theoretical philosophy.

In the conceptual preliminaries of his philosophical Encyclopedia Hegel discusses three approaches to epistemology under the headings of three ‘Attitudes of Thought Toward Objectivity’. The third of these is Jacobi’s doctrine of ‘immediate’ or intuitive knowledge. Hegel’s discussion presumes great familiarity with Jacobi’s highly polemical and now seldom read texts. In this essay I disambiguate and reconstruct Hegel’s discussion of Jacobi, in close consideration of Jacobi’s texts, showing why Hegel finds him important and what Hegel’s objections to his doctrines are. Jacobi’s importance for Hegel lies in three points. First, Hegel agrees with Jacobi’s claim, against Kant, that God and the world are themselves knowable. Second, Hegel must answer Jacobi’s charge that discursive thinking ineluctably leads to determinism and ultimately to nihilism. Third, Hegel’s analysis of Jacobi’s doctrine of ‘immediate knowledge’ reveals some points that are important to Hegel’s metaphysics. Hegel mounts five objections to Jacobi’s doctrine. First, Jacobi’s key term ‘immediacy’ illicitly equivocates among the rejection of three different kinds of ‘mediation’: syllogistic inference, the application of concepts, and representational accounts of perception. Second, Jacobi’s doctrine of a-conceptual knowledge is untenable because one must apply concepts to objects in order identify objects and thus to know what kinds of things known objects are. Third, if a fundamental point of Hegel’s holistic ontology (explained in the essay) is correct, then the identity conditions of things are interdependent, and this interdependence would render ‘immediate’ knowledge impossible. Fourth, Jacobi’s doctrine is self-referentially inconsistent: it is possible on his doctrine to prove that his doctrine is false. Finally, Jacobi’s doctrine licenses question-begging and is in principle unable to address or to settle disagreements among divergent intuitions.

: This paper explicates and defends the thesis that individual rational judgment, of the kind required for justification, whether in cognition or in morals, is fundamentally socially and historically conditioned. This puts paid to the traditional distinction, still influential today, between ‘rational’ and ‘historical’ knowledge. The present analysis highlights and defends key themes from Kant’s and Hegel’s accounts of rational judgment and justification, including four fundamental features of the ‘autonomy’ of rational judgment and one key point of Hegel’s account of ‘mutual recognition’. These themes are linked to Kant’s and Hegel’s transformation of the modern natural law tradition. The results explain why Kant’s and Hegel’s philosophy are indeed the origins of the properly pragmatic account of rationality, why the pragmatic account of rationality provides genuine rational justification and why this pragmatic account of rational justification is consistent with realism about the objects of empirical knowledge and with strict objectivity about moral norms. > Russian translation : Nelly Motroshilova, ed., К 200-летию выхода в свет «Феноменологии духа» Гегеля, 195–219. > Turkish translation : ‘Hegel’in Tinin Görüngübilimi’nde Karşihkh Onanma ve Ussal Gerekçelendirme’. MonoKL 4–5 :212–231

In the Critique of Pure Reason Kant introduced both transcendental idealism and transcendental arguments into philosophy. Transcendental arguments in general aim to establish conditions necessary for our having self-conscious experience at all. Transcendental idealism holds that such conditions do not hold independently of human subjects; those conditions obtain or are satisfied because they are generated or fulfilled by the structure or functioning of the subject’s cognitive capacities. Is transcendental idealism the only possible explanation of such conditions? I pursue this question by exploring a widely neglected issue, the transcendental affinity of the manifold of intuition. I argue the following: (1) This issue remains vital to the second edition of the Critique, even though many passages on the topic were omitted from that edition. (2) Kant’s link between transcendental idealism and transcendental arguments is substantive, not methodological. (3) Kant’s views on transcendental affinity show that there are non-subjective, transcendental material conditions for the possibility of unified self-conscious experience. (4) These conditions and Kant’s arguments for them directly undermine Kant’s own arguments for transcendental idealism. This criticism of Kant’s arguments for transcendental idealism is entirely internal to the first Critique. (5) These points reveal some serious flaws in Henry Allison’s defense of Kant’s idealism. (6) Realists, naturalists, and pragmatists have much to learn and to borrow from Kant’s transcendental analysis of the conditions of unified self-conscious experience.

This chapter argues that Hegel is a major (albeit unrecognized) epistemologist: Hegel’s Introduction provides the key to his phenomenological method by showing that the Pyrrhonian Dilemma of the Criterion refutes traditional coherentist and foundationalist theories of justification. Hegel then solves this Dilemma by analyzing the possibility of constructive self- and mutual criticism. ‘Sense Certainty’ provides a sound internal critique of ‘knowledge by acquaintance’, thus undermining a key tenet of Concept Empiricism, a view Hegel further undermines by showing that a series of non-logical a priori concepts must be used to identify any particular object of experience. Most importantly, Hegel justifies a semantics of singular cognitive reference with important anti-skeptical implications. ‘Perception’ extends Hegel’s criticism Concept Empiricism by exposing the inadequacy of Modern theories of perception (and also sense data theories) which lack a tenable concept of the identity of perceptible things. Hegel demonstrates that this concept is a priori and integrates two counterposed sub-concepts, ‘unity’ and ‘plurality’. Hegel’s examination of this concept reveals his clear awareness of what is now called the ‘binding problem’ in neurophysiology of perception, a problem only very recently noticed by epistemologists. ‘Force and Understanding’ exposes a fatal equivocation in the traditional concept of substance which thwarts our understanding of force and causal interaction. Hegel’s disambiguation of that concept enables us to comprehend how relations can be essential to physical particulars. Hegel contends that Newtonian universal gravitation shows that gravitational relations are essential to physical particulars, and he criticizes a series of attempts—including the infamous ‘inverted world’—to avoid this conclusion. Hegel’s cognitive semantics supports Newton’s Fourth Rule of philosophizing, which rejects mere logical possibilities as counter-examples to empirical hypotheses. This is an important anti-Cartesian, also anti-empiricist, insight. Finally, Hegel’s cognitive semantics reveals a previously unnoticed link between Pyrrhonian and Cartesian skepticism and empiricist anti-realism about causality within philosophy of science: all three appeal to premises, hypotheses, or counter-examples which, as mere logical possibilities, lack in principle fully determinate, cognitively legitimate meaning. ‘Consciousness’ thus establishes basic principles and features of human cognition to which Hegel returns throughout the Phenomenology. The chapter concludes by summarizing Hegel’s over-arching epistemological analysis in the Phenomenology.

Hegel’s idealism and his epistemology have been seriously misunderstood due to various deep-set preconceptions of Hegel’s expositors. Thesepreconceptions include: Idealism is inherently subjective; Hegel’s epistemology invokes intellectual intuition; Hegel was not much concerned with natural science; Natural science has no basic role to play in Hegel’s Logic. In criticizing these notions, I highlight four key features of Hegel’s account of intelligence: (1) Human cognition is active, and forges genuine cognitive links to objects that exist and have intrinsic characteristics, regardless of what we may think, believe, or say about them; (2) The Denkbestimmungen that structure and thus characterize worldly objects and events can only be grasped by intelligence (not merely by consciousness); (3) Intelligence obtains genuine objectivity by correctly identifying characteristics of a known object; (4) Central to our intelligent comprehension of Denkbestimmungen is natural scientific investigation. These findings show that Hegel’s Logic is much more closely tied with Naturphilosophie and with natural science than is commonly supposed. I conclude with eight hermeneutical pointers for understanding Hegel’s writings.

Onora O’Neill has contributed enormously to moral philosophy (broadly speaking, including both ethics and political philosophy) by identifying Kant’s unique and powerful form of normative constructivism. Frederick Neuhouser has contributed similarly by showing that all of Hegel’s standards of moral rationality aim to insure the complete development of three distinct, complementary forms of personal, moral and social freedom. However, Neuhouser’s study does not examine Hegel’s justificatory methods and principles. The present article aims to reinforce and extend Neuhouser’s findings by explicating Hegel’s basic principles for justifying practical norms. Surprisingly, Hegel’s basic principles of normative justification are rooted in Kant’s constructivism, as explicated by O’Neill. Hegel’s adaptation and development of Kant’s constructivism results in a powerful form of constructivism about moral principles which merits contemporary interest because it is more powerful and more objectivist than familiar contemporary forms of constructivism. (Slightly revised English translation by the author of „Objektive Gültigkeit zwischen Gegebenem und Gemachtem. Hegels kantischer Konstruktivismus in der praktischen Philosophie“)

It has become a veritable industry to defend Descartes against the charge of circularity and, to a lesser extent, to argue that he successfully responds to the skepticism of Sextus Empiricus. Since one of Sextus’ main skeptical ploys is to press the charge of circularity against any view, and because Descartes does reply to Sextus, it is worthwhile to criticize these efforts in the same paper. I argue that Descartes did not successfully respond to Sextus’ skeptical arguments. I argue that he is guilty of not one but of five distinct circularities in his defense of empirical knowledge, thst clearing him of such charges can only be had by rendering him naively dogmatic, and that he fails to respond to a Pyrrhonisn contraposition argument. One circle concerns divine logical voluntarism. Another concerns the semantic component of innate ideas. A third arises from his natural inability to disbelieve whatever he clearly and distinctly perceives. A fourth circularity arises in Descartes’ proof that he cannot have generated his idea of God. A final circularity concerns Descartes’ attempt to verify the reliability of his thinking nature by employing that very same thinking nature. To substantiate these claims I review the principles of Sextus’ arguments briefly and I reexamine Descartes’ texts and doctrines in detail. I also take occasion to reflect on why Descartes’ foundationalist program must have failed.

Rejection of the philosophical relevance of history of philosophy remains pronounced within contemporary analytic philosophy. The two main reasons for this rejection presuppose that strict deduction is both necessary and sufficient for rational justification. However, this justificatory ideal of scientia holds only within strictly formal domains. This is confirmed by a neglected non-sequitur in van Fraassen’s original defence of ‘Constructive Empiricism’. Conversely, strict deduction is insufficient for rational justification in non-formal, substantive domains of inquiry. In non-formal, substantive domains, rational justification is also, in part, ineliminably social and historical, for sound reasons Hegel was the first to articulate. Demonstrating this involves considering closely two key reasons many analytic philosophers (still) reject the philosophical relevance of historical philosophy (§2). As specific example of presumed, though fallacious, deductivism about justification in the non-formal domain of empirical knowledge is found in van Fraassen’s (1980) defence of ‘Constructive Empiricism’ (§3). These first two sections contend that philosophical consideration of historical philosophy is required to properly formulate key issues in non-formal domains. I next consider the further issues involved rational justification in non-formal domains, issues quintessentially posed by the Pyrrhonian Dilemma of the Criterion (§4). Finally I consider what kind of history of philosophy is required for cogent philosophy in non-formal domains (§5).

According to Kant, justifying the application of mathematics to objects in natural science requires metaphysically constructing the concept of matter. Kant develops these constructions in the Metaphysical Foundations of Natural Science (MAdN). Kant’s specific aim is to develop a dynamic theory of matter to replace corpuscular theory. In his Preface Kant claims completely to exhaust the metaphysical doctrine of body, but in the General Remark to MAdN ch. 2, “Dynamics,” Kant admits that once matter is reconceived as basic forces, it is no longer possible to construct the concept of matter. I argue that Kant’s admission is only the tip of the problem, and that none of Kant’s commentators has fully grasped the problems infecting the MAdN that underlie Kant’s admission. I show that Kant’s proof that matter consists of forces is fallacious. I then re-analyze the circularity in Kant’s definition of density, criticizing both Adickes’ formulations and his later dissolution of it. I also show that a third circularity infects the relations between Kant’s treatment of “Dynamics” and “Mechanics” (MAdN ch. 3). These three fundamental problems demonstrate the untenability of Kant’s metaphysical method, and they require the radical revision of the relation between mathematics and metaphysics Kant undertakes in his opus postumum. I show that some of Kant’s most surprising and critical later claims about the Critical philosophy are correct, and that they require the sorts of remedies Kant contemplates in the opus postumum. (I defend the essentially correct analyses offered by Burkhard Tuschling and Eckart Forster against criticisms by Michael Friedman.)