This essay presents deductive arguments to an introductory-level audience via a discussion of Aristotle's three types of rhetoric, the goals of and differences between deductive and non-deductive arguments, and the major features of deductive arguments (e.g., validity and soundness).

First, I consider J.L. Mackie's deductive argument from evil, noting that required modifications to his premises, especially those dealing with what it is to be a good person and omnipotence, do not entail that God would be required to eliminate evil completely. Hence, no contradiction exists between God's existence, possession of certain properties, and the existence of evil. Second I evaluate McCloskey's arguments against reasons for evil often suggested by the theist: that evil is a means to achieving (...) the good, that evil is a by-product of securing the good, and that certain goods are logically dependent on the existence of certain evils. I argue that in none of these objections is McCloskey successful. (shrink)

Juhani Yli-Vakkuri has argued that the Twin Earth thought experiments offered in favour of semantic externalism can be replaced by a straightforward deductive argument from premisses widely accepted by both internalists and externalists alike. The deductive argument depends, however, on premisses that, on standard formulations of internalism, cannot be satisfied by a single belief simultaneously. It does not therefore, constitute a proof of externalism. The aim of this article is to explain why.

This argument map justifies the claim that using only deductive argument schemes in computer-supported argument visualization stimulates reflection on some of one's implicit background assumptions.

T. Govier's description of ‘conductive argument’ and 'A priori analogy' is taken as a start to investigate non-deductive argumentation. It is here argued, that the nature of those types can be better understood when taking up a dynamic view (in addition to the usual structural view). The concepts of ‘frame’ and ‘position’ are constructed in order to establish such a twofold approach.

This essay is basically divided into two parts. The first deals with the similarities between reductio ad absurdum arguments and slippery slope arguments. The chief example comes from Thomas Hobbes’s Leviathan, which advances an argument for the necessity of government for humane living. The second addresses some pedagogical concerns centered around another pair of arguments: the argument by complete enumeration and the argument by inductive generalization. The illustration for this pair comes from the arts. I finish with (...) a suggestion that pairs like the above can be as effectively used in shorter, non-regular critical reasoning or introductory logic courses as those in mid-term or summer courses. Such pairing can demonstrate a good use of mixing and matching deductive and non-deductive arguments in teaching logic. (shrink)

ABSTRACT At the core of Kant’s theoretical philosophy lies the deduction of the categories: his effort to secure the distinctiveness of sensibility and understanding and to provide a necessary relation between the domains of these faculties. The argument for this claim is presented in two different versions - i.e., the A and B editions of the Critique of pure reason - and is one of the most puzzling in Kant’s corpus. The common view in the literature that considers the importance (...) of the A-deduction and tries to present its structure is that it must be understood in the light of the B-deduction argument. I aim at contesting this view and offering an internal reconstruction of the A-deduction argument which reveals its unique methodology. The thesis advanced is that the A-deduction follows an analytical methodology and that this methodology does not allow the accomplishment of the task of the deduction stated in Kant’s effort. At first, Kant’s retrospect of the A-deduction is taken into account. After that, a consideration of the part of the argument described as ‘subjective deduction’ is carried out. (shrink)

Both 'persuasion' and 'rational convincing' play a major role in argumentative discourse but only the latter is said to constitute argument and be amenable to traditional logical analysis. I argue against this assumption by showing that there are many paradigmatic instances of persuasion which are best understood as implicit arguments. So understood, acts of persuasion can conform to well recognized argument schemata and are best assessed accordingly. I shall argue that the attempt to distinguish arg ument and persuasion is (...) fraught with difficulties. I contrast my conclusions with those of authors like Gilbert, Johnson, and Johnson and Blair. (shrink)

In philosophy, an argument consists of a set of statements called premises that serve as grounds for affirming another statement called the conclusion. Philosophers typically distinguish arguments in natural languages (such as English) into two fundamentally different types: deductive and inductive. Each type of argument is said to have characteristics that categorically distinguish it from the other type. The two types of argument are also said to be subject to differing evaluative standards. Pointing to paradigmatic examples of each (...) type of argument helps to clarify their key differences. The distinction between the two types of argument may hardly seem worthy of philosophical reflection, as evidenced by the fact that their differences are usually presented as straightforward, such as in many introductory philosophy textbooks. Nonetheless, the question of how best to distinguish deductive from inductive arguments, and indeed whether there is a coherent categorical distinction between them at all, turns out to be considerably more problematic than commonly recognized. This article identifies and discusses a range of different proposals for marking categorical differences between deductive and inductive arguments while highlighting the problems and limitations attending each. Consideration is also given to the ways in which one might do without a distinction between two types of argument by focusing solely on the application of evaluative standards to arguments instead. (shrink)

A simple summary of the difference between induction and deduction.

Richard Arthur’s _Natural Deduction_ provides a wide-ranging introduction to logic. In lively and readable prose, Arthur presents a new approach to the study of logic, one that seeks to integrate methods of argument analysis developed in modern “informal logic” with natural deduction techniques. The dry bones of logic are given flesh by unusual attention to the history of the subject, from Pythagoras, the Stoics, and Indian Buddhist logic, through Lewis Carroll, Venn, and Boole, to Russell, Frege, and Monty Python.

The traditional No-Miracles Argument (TNMA) asserts that the novel predictive success of science would be a miracle, and thus too implausible to believe, if successful theories were not at least approximately true. The TNMA has come under fire in multiple ways, challenging each of its premises and its general argumentative structure. While the TNMA relies on explaining novel predictive success via the truth of the theories, we put forth a deductive version of the No-Miracles argument (DNMA) that avoids inference (...) to the best explanation entirely. Instead, a relatively simple empirical framework and a probabilistic analysis can accomplish the ambitious goals of the TNMA while entirely sidestepping its problems. This close-but-distinct argument has many independent strengths and comparatively few weaknesses. Indeed, objections tailored specifically to the DNMA reveal surprising insights into how exactly NMAs are neither circular nor question-begging, as has been widely speculated. (shrink)

One of the principle aims of the B version of Kant’s transcendental deduction is to show how it is possible that the same “I think” can accompany all of my representations, which is a transcendental condition of the possibility of judgment. Contra interpreters such as A. Brook, I show that this “I think” is an a priori (reflected) self-consciousness; contra P. Keller, I show that this a priori self-consciousness is first and foremost a consciousness of one’s personal identity from a (...) first person point of view. (shrink)

a recent paper, Fábio Perin Shecaira proposes a defence of Waller’s deductivist schema for moral analogical argumentation. This defence has several flaws, the most important of them being that many good analogical arguments would be deemed bad or deficient. Additionally, Shecaira misrepresents my alternative account as something in between deductivism and non-deductivism. This paper is both an attempt at solving this misunderstanding and an analysis and criticism of Waller and Shecaira’s forms of deductivism.

Bruce Waller has defended a deductive reconstruction of the kinds of analogical arguments found in ethics, law, and metaphysics. This paper demonstrates the limits of such a reconstruction and argues for an alternative. non-deductive reconstruction. It will be shown that some analogical arguments do not fit Waller's deductive schema, and that such a schema does not allow for an adequate account of the strengths and weaknesses of an analogical argument. The similarities and differences between the (...) account defended herein and the Trudy Govier's account are discussed as well. (shrink)

David Miller claims that every valid deductive argument begs the question. Other philosophers and logicians have made similar claims. I show that the claim is false. Its appeal depends on the existence of logical terminology, particularly concerning what a proposition 'contains' or its 'logical content,' that is best understood as metaphoric and that, given its aptness to mislead, would be better eschewed. I show how the terminology appears to derive from early modern theories of the nature of mind, ideas (...) and reasoning that have since been rejected. (shrink)

Popper and Miller (1983) have presented an argument purporting to establish the impossibility of inductive probability. Here I discuss critically their characterization of a deductive part of nondeductive support, a point that has not figured centrally in previous responses.

Bruce Waller has defended a deductive reconstruction of the kinds of analogical arguments found in ethics, law, and metaphysics. This paper demonstrates the limits of such a reconstruction and argues for an alternative. non-deductive reconstruction. It will be shown that some analogical arguments do not fit Waller's deductive schema, and that such a schema does not allow for an adequate account of the strengths and weaknesses of an analogical argument. The similarities and differences between the (...) account defended herein and the Trudy Govier's account are discussed as well. (shrink)

In this paper, we propose an argumentation formalism that allows for both deductive and abductive argumentation, where ‘deduction’ is used as an umbrella term for both defeasible and strict ‘forward’ inference. Our formalism is based on an extended version of our previously proposed information graph formalism, which provides a precise account of the interplay between deductive and abductive inference and causal and evidential information. In the current version, we consider additional types of information such as abstractions which allow (...) domain experts to be more expressive in stating their knowledge, where we identify and impose constraints on the types of inferences that may be performed with the different types of information. A new notion of attack is defined that captures a crucial aspect of abductive reasoning, namely that of competition between abductively inferred alternative explanations. Our argumentation formalism generates an abstract argumentation framework and thus allows arguments to be formally evaluated. We prove that instantiations of our argumentation formalism satisfy key rationality postulates. (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)

This article concerns the structure of defeasible arguments like: 'If Bob has red spots, Bob has the measles; Bob has red spots; therefore Bob has the measles.' The issue is whether such arguments have the form of modus ponens or not. Either way there is a problem. If they don't have the form of modus ponens, the common opinion to the contrary taught in leading logic textbooks is wrong. But if they do have the form of modus ponens, (...) doubts are raised about the conventional dogma that all arguments having the form of modus ponens are deductively valid. By carefully examining arguments on both sides of the issue, reasonable doubts are raised about the view that all arguments having a modus ponens form are valid. (shrink)

Major recent interpretations of Kant's first "critique" (wolff, Strawson, Bennett) have taken his transcendental deduction to be an argument from the fact of consciousness to the existence of an objective world. I argue that it is unclear such an argument can succeed and there are overwhelming reasons to believe kant understood his deduction as having a very different form, namely as moving from the premise that there is empirical knowledge to the conclusion that there are universally valid pure categories. Detailed (...) support for this contention is offered in an analysis of the second edition version of the deduction. (shrink)

In the middle of a conference on the logic of science, an eminent biologist once said: “Does it not bother you guys that we scientists do not use any logic at all.” This statement was meant to be a friendly provocation, but there also was a serious message. Scientists often say that the logical analyses are exercises in formal logic and fail to illuminate what the scientists are doing, actual scientific practice. This recurring complaint, although not completely as I will (...) suggest, has not gone unnoticed in the philosophy of science. Indeed, the current trend in analytic philosophy of science as well as in teaching the method of science has been away from logic as a means of illuminating scientific inquiry. (shrink)

In the middle of a conference on the logic of science, an eminent biologist once said: “Does it not bother you guys that we scientists do not use any logic at all.” This statement was meant to be a friendly provocation, but there also was a serious message. Scientists often say that the logical analyses are exercises in formal logic and fail to illuminate what the scientists are doing, actual scientific practice. This recurring complaint, although not completely as I will (...) suggest, has not gone unnoticed in the philosophy of science. Indeed, the current trend in analytic philosophy of science as well as in teaching the method of science has been away from logic as a means of illuminating scientific inquiry. (shrink)

I first criticize strawson's account of the transcendental deduction, And then argue that wittgenstein's considerations (in his later work) of the rule-Governed nature of judgment can be used to reconstruct a valid argument for a certain kind of objectivity, Which excludes solipsims. I suggest how kant's talk of synthesis can be reinterpreted in the light of this, As indeed can the doctrine of empirical realism and transcendental idealism.

1. In May 2013 I had an email exchange with Philippe Besnard, continued in September that year, on his paper with Amgoud and Besnard (2013) and its relevance for the ASPIC+ framework (Modgil & Prak...

The goal of Kant’s transcendental deduction is to demonstrate the reciprocal implication of self-consciousness and objectivity. Kant’s argument is that the subject possesses a priori cognizance concerning the thoroughgoing identity of itself and that this entails a priori for the subject cognition of the manners in which the combining activities of individual cognitive states must and can occur if its self-identity is to be maintained. Kant proposes that the cognitive subject makes judgments concerning its identity, and then shows that these (...) judgments must subscribe to formal rules of synthesis relating cognitive representations, for which the subject affirms such identity, to a domain of empirical things-in-themselves or enduring objects. (shrink)

This paper critically examines a formal argument against deducing ‘ought’-judgments from ‘is’-judgments, an argument suggested by a literal reading of a famous passage in Hume'sTreatise of Human Nature. According to this argument, judgments of the two kinds have different logical structures (i.e., their subjects are differently related to their predicates) and this difference disallows cross-categorical deductive inferences. I draw on Fregean accounts of the ‘is’- copula and on syntactical interpretations of ‘ought’-judgments that have become standard in deontic logic to (...) argue that twentieth century work in philosophical grammar and logic casts doubt on all three of the argument's premises. (shrink)