In the late 19th century great changes in theories of light and electricity were in direct conflict with certitude, the view that scientific knowledge is infallible. What is, then, the epistemic status of scientific theory? To resolve this issue Duhem and Poincaré proposed images of fallible knowledge, Instrumentalism and Conventionalism, respectively. Only in 1919–1922, after Einstein's relativity was published, he offered arguments to support Fallibilism, the view that certainty cannot be achieved in science. Though Einstein did not consider Duhem's Instrumentalism, (...) he argued against Poincaré's Conventionalism. Hitherto, Einstein's Fallibilism, as presented at first in a rarely known essay of 1919, was left in the dark. Recently, Howard obscured its meaning. Einstein's essay was never translated into English. In my paper I provide its translation and attempt to shed light on Einstein's view and its context; I also direct attention to Einstein's images of philosophical opportunism in scientific practice. (shrink)

Fichte argues that the conclusion of Kant’s transcendental deduction of the categories is correct yet lacks a crucial premise, given Kant’s admission that the metaphysical deduction locates an arbitrary origin for the categories. Fichte provides the missing premise by employing a new method: a genetic deduction of the categories from a first principle. Since Fichte claims to articulate the same view as Kant in a different, it is crucial to grasp genetic deduction in relation to the (...) sorts of deduction that Kant offers. I propose to interpret genetic deduction as the simultaneous fulfillment of two tasks: answering the question quid facti by deriving the categories from the I and answering the question quid juris by establishing our entitlement to the categories as conditions of experience. While the second task represents Fichte’s agreement with Kant’s transcendental deduction, the first reflects his correction of Kant’s metaphysical deduction. (shrink)

A system of typed terms which corresponds with the classical natural deduction with one conclusion and full logical symbols is defined. Church–Rosser property of the system is proved using an extended method of parallel reduction.

According to non-conceptualist interpretations, Kant held that the application of concepts is not necessary for perceptual experience. Some have motivated non-conceptualism by noting the affinities between Kant's account of perception and contemporary relational theories of perception. In this paper I argue (i) that non-conceptualism cannot provide an account of the Transcendental Deduction and thus ought to be rejected; and (ii) that this has no bearing on the issue of whether Kant endorsed a relational account of perceptual experience.

Peter Slezak and William Boos have independently advanced a novel interpretation of Descartes's "cogito". The interpretation portrays the "cogito" as a diagonal deduction and emphasizes its resemblance to Godel's theorem and the Liar. I object that this approach is flawed by the fact that it assigns 'Buridan sentences' a legitimate role in Descartes's philosophy. The paradoxical nature of these sentences would have the peculiar result of undermining Descartes's "cogito" while enabling him to "disprove" God's existence.

This essay partly builds on and partly criticizes a striking idea of Dieter Henrich. Henrich argues that Kant's distinction in the first Critique between the question of fact (quid facti) and the question of law (quid juris) provides clues to the argumentative structure of a philosophical "Deduction". Henrich suggests that the unity of apperception plays a role analogous to a legal factum. By contrast, I argue, first, that the question of fact in the first Critique is settled by the (...) Metaphysical Deduction, which establishes the purity of origin of the Categories, and, second, that in the second Critique, the relevant factum is the Fact of Reason, which amounts to the fact that the Moral Law is pure in origin. (shrink)

I give an argument against nonconceptualist readings of Kants claim that intuitions and concepts constitute two distinct kinds of representation than is assumed by proponents of nonconceptualist readings. I present such an interpretation and outline the alternative reading of the Deduction that results.

The aim of this paper is twofold. First, I want to argue that the distinction between induction and deduction is less clear-cut than traditionally assumed, and that, moreover, most reasoning processes in the sciences involve an integration of inductive and deductive steps. Next, I want to show how so-called adaptive logics may lead to a better understanding of this integrated use of induction and deduction.

We argue that the need for commentary in commonly used linear calculi of natural deduction is connected to the “deletion” of illocutionary expressions that express the role of propositions as reasons, assumptions, or inferred propositions. We first analyze the formalization of an informal proof in some common calculi which do not formalize natural language illocutionary expressions, and show that in these calculi the formalizations of the example proof rely on commentary devices that have no counterpart in the original proof. (...) We then present a linear natural deduction calculus that makes use of formal illocutionary expressions in such a way that unique readability for derivations is guaranteed – thus showing that formalizing illocutionary expressions can eliminate the need for commentary. (shrink)

A normalization procedure is given for classical natural deduction with the standard rule of indirect proof applied to arbitrary formulas. For normal derivability and the subformula property, it is sufficient to permute down instances of indirect proof whenever they have been used for concluding a major premiss of an elimination rule. The result applies even to natural deduction for classical modal logic.

This article argues that many (often Anglophone) interpreters of the Deduction have mistakenly identified Kant's aim as vindicating ordinary knowledge of objects and as refuting Hume's (alleged) skepticism about such knowledge. Instead, the article contends that Kant's aims were primarily negative. His primary mission (in the Deduction) was not to justify application of the categories to experience, but to show that any use beyond the domain of experience could not be justified. To do this, he needed to show (...) that their proper use in attaining metaphysical knowledge was restricted to (actual and possible) experience. The central theoretical claims of previous metaphysics were thus rendered void. Kant was not out to save ordinary knowledge from the skeptic, at least not originally, since he did not think such knowledge was in danger. Rather, he wanted to sustain the skeptical claim that we cannot justify metaphysical claims about things in themselves, hence that we cannot gain metaphysical knowledge about the existence of God, the immortality of the soul, the beginning of time, and the least parts of matter. He wanted to achieve this result in a more theoretically satisfying manner than had skeptical authors. Doing so would also allow him to curb certain forms of skeptical empiricism, by showing that we cannot disprove, or rule out as unintelligible, human freedom, an afterlife, or divine providence. The article ends by considering the retrospective rereadings of the Deduction by Hermann Cohen and P. F. Strawson, concluding that these rereadings force Kant's text into an alien mold, thereby diminishing its philosophical value as a work with its own distinctive aims and methods. (shrink)

This article studies the mathematical properties of two systems that model Aristotle's original syllogistic and the relationship obtaining between them. These systems are Corcoran's natural deduction syllogistic and ?ukasiewicz's axiomatization of the syllogistic. We show that by translating the former into a first-order theory, which we call T RD, we can establish a precise relationship between the two systems. We prove within the framework of first-order logic a number of logical properties about T RD that bear upon the same (...) properties of the natural deduction counterpart ? that is, Corcoran's system. Moreover, the first-order logic framework that we work with allows us to understand how complicated the semantics of the syllogistic is in providing us with examples of bizarre, unexpected interpretations of the syllogistic rules. Finally, we provide a first attempt at finding the structure of that semantics, reducing the search to the characterization of the class of models of T RD. (shrink)

I critically examine one central line of reasoning in Mario Caimi's book »Kant's B Deduction« (Cambridge Publishing, 2014).

Chapter 4 of Dennis Schulting’s book Kant’s Radical Subjectivism targets those commentators who take there to be a gap in the transcendental deduction of the categories, arguing instead that there is no gap between the necessary application of the categories and their exemplification in the object of experience. In these comments on the chapter, I suggest a minimal sense in which the fact that there is a gap is non-negotiable. The interesting question is not whether there is a gap (...) which needs to be bridged, but how and why Kant makes the step from subjectivity to objectivity. (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)

By taking into account some texts published between the first and the second edition of the Critique of Pure Reason that have been neglected by most of those who have dealt with the deduction of the categories, I argue that the core of the deduction is to be identified as the ‘almost single inference from the precisely determined definition of a judgment in general’, which Kant adumbrates in the Metaphysical Foundations in order to ‘make up for the deficiency’ (...) of the A-deduction. Whereas the first step of the B-deduction is an attempt to show that the manifold of an intuition belongs to the ‘necessary unity of self-consciousness’ by means of the synthesis of the understanding, the second step has the task of showing that the very same synthesis is responsible for the spatio-temporal unity of the manifold. Thus, Kant's ‘answer to Hume’ is that no spatio-temporal objects of experience at all are merely ‘given’, independently of the conceptual activities of the understanding. Against the established view I substantiate the claim that with this ‘almost single inference’ of the second proof step the distinction between judgments of perception and judgments of experience consequently vanished from Kant's thinking. (shrink)

In "Beyond the Myth of the Myth: A Kantian Theory of Non-Conceptual Content", Robert Hanna argues for a very strong kind of non-conceptualism, and claims that this kind of non-conceptualism originally has been developed by Kant. But according to "Kant's Non-Conceptualism, Rogue Objects and the Gap in the B Deduction", Kant's non-conceptualism poses a serious problem for his argument for the objective validity of the categories, namely the problem that there is a gap in the B Deduction. This (...) gap is that the B Deduction goes through only if conceptualism is true, but Kant is a non-conceptualist. In this paper I argue, contrary to what Hanna claims, that there is not a gap in the B Deduction. (shrink)

The main result of this paper is a normalizing system of natural deduction for the full language of intuitionistic linear logic. No explicit weakening or contraction rules for -formulas are needed. By the systematic use of general elimination rules a correspondence between normal derivations and cut-free derivations in sequent calculus is obtained. Normalization and the subformula property for normal derivations follow through translation to sequent calculus and cut-elimination.

The notion of normal proof theory, and yet it has been somewhat neglected by the systems of equational logic. The intention here is then to show the normalization procedure for the equational logic of the Labelled Natural Deduction system . With this we believe we are making a step towards filling a gap in the literature on equational logic. Besides presenting a normalization procedure for the LND equational fragment, we employ a new method to prove the normalization theorems for (...) equational logic: proof transformation by rewriting, based on a algebraic calculus on the 'rewrite reasons'. (shrink)

So we stand more or less on our own when trying to make sense of a specifically transcendental way of argumentation. Fortunately we are not all that alone, since independently of a direct Kantian influence the problem of transcendental arguments has stimulated a considerable debate among analytical philosophers. And we still have Kant’s own text. We shall start, therefore, by reminding ourselves of this debate and then go back to Kant. We shall deliberately not proceed the other way round in (...) order to avoid as much as possible what one may call a Kantian bias. The representatives chosen for analytical philosophy are Wittgenstein, Quine, and Strawson. We shall then consider the Kantian account of the meaning of the term "transcendental". After this preparation we are in a position to examine the claim of a ‘transcendental deduction,’ which is one of the most controversial issues arising from the Critique of Pure Reason. (shrink)

I argue for a novel, non-subjectivist interpretation of Kant’s transcendental idealism. Kant’s idealism is often interpreted as specifying how we must experience objects or how objects must appear to us. I argue to the contrary by appealing to Kant’s Transcendental Deduction. Kant’s Deduction is the proof that the categories are not merely subjectively necessary conditions we need for our cognition, but objectively valid conditions necessary for objects to be appearances. My interpretation centres on two claims. First, Kant’s method (...) of self-knowledge consists in his determining what makes our cognitive faculty finite in contrast to God’s infinite cognitive faculty. Second, Kant’s limitation of our knowledge to appearances consists in his developing an account according to which appearances and our finite cognitive faculty are conceived of in terms of each other and in contrast to noumena in the positive sense and God’s infinite cognitive faculty. (shrink)

Gentzen writes in the published version of his doctoral thesis Untersuchungen über das logische Schliessen that he was able to prove the normalization theorem only for intuitionistic natural deduction, but not for classical. To cover the latter, he developed classical sequent calculus and proved a corresponding theorem, the famous cut elimination result. Its proof was organized so that a cut elimination result for an intuitionistic sequent calculus came out as a special case, namely the one in which the sequents (...) have at most one formula in the right, succedent part. Thus, there was no need for a direct proof of normalization for intuitionistic natural deduction. The only traces of such a proof in the published thesis are some convertibilities, such as when an implication introduction is followed by an implication elimination [1934–35, II.5.13]. It remained to Dag Prawitz in 1965 to work out a proof of normalization. Another, less known proof was given also in 1965 by Andres Raggio.We found in February 2005 an early handwritten version of Gentzen's thesis, with exactly the above title, but with rather different contents: Most remarkably, it contains a detailed proof of normalization for what became the standard system of natural deduction. The manuscript is located in the Paul Bernays collection at the ETH-Zurichwith the signum Hs. 974: 271. Bernays must have gotten it well before the time of his being expelled from Göttingen on the basis of the racial laws in April 1933. (shrink)

In the context of a critique of James Conant’s (2016) important new reading of the main argument of the Deduction, I present my current, most detailed interpretation of the well-known Leitfaden passage at A79, which in my view has been misinterpreted by a host of prominent readers. The Leitfaden passage is crucial to understanding the argument of, not just the so-called Metaphysical Deduction, but also the Transcendental Deduction. This new account expands and improves upon the account of (...) the Leitfaden I gave in Chap. 5 of Kant’s Deduction From Apperception. While I agree with the core of Conant’s critique of what he calls the ‘layer-cake’ reading of the Deduction argument, in this new account I make clearer my position on why the unity of judgement, in which concepts and intuitions are a priori synthetically unified, is wholly determined in virtue of the unity of apperception as the unitary function of the understanding, without this leading to a strong form of conceptualism such as that of Conant and others. (shrink)

In this paper we make some observations about Natural Deduction derivations [Prawitz, 1965, van Dalen, 1986, Bell and Machover, 1977]. We assume the reader is familiar with it and with proof-theory in general. Our development will be simple, even simple-minded, and concrete. However, it will also be evident that general ideas motivate our examples, and we think both our specific examples and the ideas behind them are interesting and may be useful to some readers. In a sentence, the bare (...) technical content of this paper is: Extending natural deduction with global well-formedness conditions can neatly and cheaply capture classical and intermediate logics. The interest here is in the ‘neatly’ and ‘cheaply’. By ‘neatly’ we mean ‘preserving proof-normalisation’,1 and ‘maintaining the subformula property’, and by ‘cheaply’ we mean ‘preserving the formal structure of deductions’ (so that a deduction in the original system is still, formally, a deduction in the extended system, and in particular it requires no extra effort to write just because it is in the extended system). To illustrate what we have in mind consider intuitionistic first-order logic (FOL) [van Dalen, 1986] as a paradigmatic example of a formal notion of deduction. A natural deduction derivation (or deduction) is an inductively defined tree structure where each node contains an instance of a formula. A deduction is valid when each successive node follows from its predecessors in accordance with some predetermined inference rules. A particular attraction of Natural Deduction is its clean and economical presentation. Here for example are deduction (fragments) proving A ∧ B from A and B, and ∀x. (P (x) ∧ Q(x)) from ∀x. P (x) and ∀x. Q(x): ∀x. P (x) (∀E). (shrink)

It is often said that in a purely formal perspective, intuitionistic logic has no obvious advantage to deal with the liar-type paradoxes. In this paper, we will argue that the standard intuitionistic natural deduction systems are vulnerable to the liar-type paradoxes in the sense that the acceptance of the liar-type sentences results in inference to absurdity (⊥). The result shows that the restriction of the Double Negation Elimination (DNE) fails to block the inference to ⊥. It is, however, not (...) the problem of the intuitionistic approaches to the liar-type paradoxes but the lack of expressive power of the standard intuitionistic natural deduction system. We introduce a meta-level negation for a given system and a meta-level absurdity, ⋏, to the intuitionistic system. We shall show that in the system, the inference to ⊥ is not given without the assumption that the system is complete. Moreover, we consider the Double Meta-Level Negation Elimination rules (DMNE) which implicitly assume the completeness of the system. Then, the restriction of DMNE can rule out the inference to ⊥. (shrink)

By a sentential logic we understand a pair, where S is a sentential language, i.e. an absolutely free algebra freely generated by an infinite set p, q, r,... of sentential variables and endowed with countably many finitary connectives §1, §2,... and C is a consequence operation on S, the underlying set of S, satisfying the condition of structurality: eC ⊆ C, for every endomorphism e of S and for every X ⊆ S. If no confusion is likely we shall identify (...) a logic with its consequence operation C. A logic C is standard if C = [ {C : Y ⊆ X & Y is finite}, for all X ⊆ S. (shrink)

According to a familiar reading of Kant, he denies the possibility alleged by the rationalists of our having non-sensible or intellectual intuition. I argue in this article that he simply holds the possibility to be groundless. To put the contrast in terms of a distinction Kant makes in the A-Paralogisms, he raises a “dogmatic” objection to the rationalists in the former case, and a “critical” one in the latter. By analyzing the two-step argument in the B-Deduction, I defend the (...) “critical” reading, which may, I hope, shed light on how Kant can justify his claim – which may be regarded as a second-order, methodological one pivotal to his Critical project – that possible experience serves as the only guideline for proving that we can cognize objects a priori. (shrink)

The goal of this note is to analyze the ideas presented by Alberto Moretti (1984) in his article “Gentzen y la naturalidad de la deducción” regarding the importance of sequent calculi. My goal is to argue that the difference between these systems and those of natural deduction lies fundamentally in the way in which structural rules can be implicit in them, and that, unlike what Moretti proposes, natural deduction calculi are particularly appropriate for characterizing the notion of consequence.

A constructive proof is provided for the claim that classical first-order logic admits of a natural deduction formulation featuring the subformula property.

Natural deduction systems for classical, intuitionistic and modal logics were deeply investigated by Prawitz [D. Prawitz, Natural Deduction: A Proof-theoretical Study, in: Stockholm Studies in Philosophy, vol. 3, Almqvist and Wiksell, Stockholm, 1965. Reprinted at: Dover Publications, Dover Books on Mathematics, 2006] from a proof-theoretical perspective. Prawitz proved weak normalization for classical logic only for a language without logical or, there exists and with a restricted application of reduction ad absurdum. Reduction steps related to logical or, there exists (...) and classical negation bring about many problems solved only rather recently. For classical S5 modal logic, Prawitz defined a normalizable system, but for a language without logical or, there exists, ◊ and, for a propositional language without ◊, Medeiros [M.da P.N. Medeiros, A new S4 classical modal logic in natural deduction, Journal of Symbolic Logic 71 799–809] presented a normalizable system for classical S4. We can mention many cut-free Gentzen systems for S4, S5 and K45/K45D, some normalizable natural deduction systems for intuitionistic modal logics and one more for full classical S4, but not for full classical S5. Here our focus is on the definition of a classical and normalizable natural deduction system for S5, taking not only □ and ◊ as primitive symbols, but also all connectives and quantifiers, including classical negation, disjunction and the existential quantifier. The normalization procedure is based on the strategy proposed by Massi [C.D.B. Massi, Provas de normalizaçaõ para a lógica clássica, Ph.D. Thesis, Departamento de Filosofia, UNICAMP, Campinas, 1990] and Pereira and Massi [L.C. Pereira, C.D.B. Massi, Normalização para a lógica clássica, in: O que nos faz pensar, Cadernos de Filosofia da PUC-RJ, vol. 2, 1990, pp. 49–53] for first-order classical logic to cope with the combined use of classical negation, disjunction and the existential quantifier. Here we extend such results to deal with □ and ◊ too. The elimination rule for ◊ uses the notions of connection and of essentially modal formulas already proposed by Prawitz for the introduction of □. Beyond weak normalization, we also prove the subformula property for full S5. (shrink)