In redefining logic, philosophers need to go back to the Aristotelian roots of the subject, to expand the boundaries of the subject to include informal logic and to give up false oppositions between informal and formal logic.

This paper offers a solution to the problem of understanding how a fallacious argument can be deceptive by “seeming to be valid”, or (better) appearing to be a better argument of its kind than it really is. The explanation of how fallacies are deceptive is based on heuristics and paraschemes. Heuristics are fast and frugal shortcuts to a solution to a problem that sometimes jump to a conclusion that is not justified. In fallacious instances, according to the theory proposed, this (...) jump overlooks prerequisites of the defeasible argumentation scheme for the type of argument in question. Three informal fallacies, argumentum ad verecundiam , argumentum ad ignorantiam and fear appeal argument, are used to illustrate and explain the theory. (shrink)

What are the historical origins of the argumentum ad consequentiam, the argument from consequences, sometimes featured as an informal fallacy in logic textbooks? As shown in this paper, knowledge of the argument can be traced back to Aristotle. And this type of argument shows a spotty history of recognition in logic texts and manuals over the centuries. But how it got into the modern logic textbooks as a fallacy remains somewhat obscure. Its modern genesis is traced to the logic text (...) of James McCosh. (shrink)

In a recent paper (Linguistics and Philosophy 23, 4, June 2000), Jason Stanley argues that there are no `unarticulated constituents', contrary to what advocates of Truth-conditional pragmatics (TCP) have claimed. All truth-conditional effects of context can be traced to logical form, he says. In this paper I maintain that there are unarticulated constituents, and I defend TCP. Stanley's argument exploits the fact that the alleged unarticulated constituents can be `bound', that is, they can be made to vary with the values (...) introduced by operators in the sentence. I show that Stanley's argument rests on a fallacy, and I provide alternative analyses of the data. (shrink)

Why are personal attacks so powerful? In political debates, speeches, discussions and campaigns, negative character judgments, aggressive charges and charged epithets are used for different purposes. They can block the dialogue, trigger value judgments and influence decisions; they can force the interlocutor to withdraw a viewpoint or undermine his arguments. Personal attacks are not only multifaceted dialogical moves, but also complex argumentative strategies. They can be considered as premises for further arguments based on signs, generalizations or consequences. They involve tactics (...) for arousing emotions such as fear, hate or contempt, or for ridiculing the interlocutor. The twofold level of investigation presented in this paper is aimed at distinguishing the different roles that ad hominem have in a dialogue and bringing to light their hidden dimensions. The reasoning structure of each type of attack will be distinguished from the tactics used to increase its effectiveness and conceal its weaknesses. (shrink)

This paper shows how reasoning from best explanation combines with linguistic and factual presumptions during the process of retrieving a speaker’s intention. It is shown how differences between presumptions need to be used to pick the best explanation of a pragmatic manifestation of a dialogical intention. It is shown why we cannot simply jump to an interpretative conclusion based on what we presume to be the most common purpose of a speech act, and why, in cases of indirect speech acts, (...) we need to depend on an abductive process of interpretation. (shrink)

The representation and classification of the structure of natural arguments has been one of the most important aspects of Aristotelian and medieval dialectical and rhetorical theories. This traditional approach is represented nowadays in models of argumentation schemes. The purpose of this article is to show how arguments are characterized by a complex combination of two levels of abstraction, namely, semantic relations and types of reasoning, and to provide an effective and comprehensive classification system for this matrix of semantic and quasilogical (...) connections. To this purpose, we propose a dichotomous criterion of classification, transcending both levels of abstraction and representing not what an argument is but how it is understood and interpreted. The schemes are grouped according to an end-means criterion, which is strictly bound to the ontological structure of the conclusion and the premises. On this view, a scheme can be selected according to the intended or reconstructed purpose of an argument and the possible strategies that can be used to achieve it. (shrink)

The representation and classification of the structure of natural arguments has been one of the most important aspects of Aristotelian and medieval dialectical and rhetorical theories. This traditional approach is represented nowadays in models of argumentation schemes. The purpose of this article is to show how arguments are characterized by a complex combination of two levels of abstraction, namely, semantic relations and types of reasoning, and to provide an effective and comprehensive classification system for this matrix of semantic and quasilogical (...) connections. To this purpose, we propose a dichotomous criterion of classification, transcending both levels of abstraction and representing not what an argument is but how it is understood and interpreted. The schemes are grouped according to an end-means criterion, which is strictly bound to the ontological structure of the conclusion and the premises. On this view, a scheme can be selected according to the intended or reconstructed purpose of an argument and the possible strategies that can be used to achieve it. (shrink)

The purpose of this paper is to analyze the structure and the defeasibility conditions of argument from analogy, addressing the issues of determining the nature of the comparison underlying the analogy and the types of inferences justifying the conclusion. In the dialectical tradition, different forms of similarity were distinguished and related to the possible inferences that can be drawn from them. The kinds of similarity can be divided into four categories, depending on whether they represent fundamental semantic features of the (...) terms of the comparison or non-semantic ones, indicating possible characteristics of the referents. Such distinct types of similarity characterize different kinds of analogical arguments, all based on a similar general structure, in which a common genus is abstracted. Depending on the nature of the abstracted common feature, different rules of inference will apply, guaranteeing the attribution of the analogical predicate to the genus and to the primary subject. This analysis of similarity and the relationship thereof with the rules of inference allows a deeper investigation of the defeasibility conditions. (shrink)

In many actual arguments, the conclusion seems intuitively to follow from the premisses, even though we cannot show that it follows logically. The traditional approach to evaluating such arguments is to suppose that they have an unstated premiss whose explicit addition will produce an argument where the conclusion does follow logically. But there are good reasons for doubting that people so frequently leave the premisses of their arguments unstated. The inclination to suppose that they do stems from the belief that (...) the only way in which an argument's conclusion can follow definitely from its premisses is to follow logically. I argue that this belief is mistaken. I propose a revision of the current generic conception of logical consequence, and its variant specifications, to avoid the paradoxes of strict implication. The revised conception can then be naturally extended to include also what we might call 'enthymematic consequence'. This concept is a kind of consequence, whose properties merit investigation. (shrink)