Being unreasonable: Perelman and the problem of fallacies

Most work on fallacies continues to conceptualize fallacious reasoning as involving a breach of a formal or quasi-formal rule. Chaim Perelman's theory of argumentation provides a way to conceptualize fallacies in a completely different way. His approach depends on an understanding of standards of rationality as essentially connected with conceptions of universality. Such an approach allows one to get beyond some of the basic problems of fallacy theory, and turns informal logic toward substantive philosophical questions. I show this by reinterpreting three so-called fallacies - theargumentum ad baculum, equivocation and composition/division - in the light of Perelman's account.     

Scope Fallacies and the “Decisive Objection” Against Endurance

From time to time, the idea that enduring things can change has been challenged. The latest challenge has come in the form of what David Lewis has called a “decisive objection”, which claims to deduce a contradiction from the idea that enduring things change with respect to their temporary intrinsics, when that idea is combined with eternalism. It is my aim in this paper to explain why I think that no argument has yet appeared that deduces a contradiction from a combination of eternalism and the idea that enduring things change with respect to their temporary intrinsics, except ones that do so by committing scope fallacies.

The eco-cognitive model of abduction: Ἀπαγωγή now: Naturalizing the logic of abduction

Abduction (ἀπαγωγή, in ancient Greek, often translated as “leading away” or “reduction”) is a procedure in which something that lacks classical explanatory epistemic virtue can be accepted because it has virtue of another kind: Gabbay and Woods [15] contend (GW-schema) that abduction presents an ignorance-preserving or (ignorance-mitigating) character. From this perspective abductive reasoning is a response to an ignorance-problem; through abduction the basic ignorance – that does not have to be considered a total “ignorance” – is neither solved nor left intact. Abductive reasoning is an ignorance-preserving accommodation of the problem at hand. Is abduction really ignorance-preserving? To better answer this question I will introduce (and take advantage of) an eco-cognitive model (EC-Model) of abduction. It will be illustrated that through abduction, knowledge can be enhanced, even when abduction is not considered an inference to the best explanation in the classical sense of the expression, that is an inference necessarily characterized by an empirical evaluation phase, or an inductive phase, as Peirce called it. To further deepen the eco-cognitive character of abduction a simple genealogy of logic is provided: Aristotle clearly states that in syllogistic theory local/environmental cognitive factors – external to that peculiar inferential process, for example regarding users/reasoners, are given up. Indeed, to define syllogism Aristotle first of all insists that all syllogisms are valid and contends that the necessity of this kind of reasoning is related to the circumstance that “no further term from outside (ἔξωθɛν) is needed”, in sum syllogism is the fruit of a kind of eco-cognitive immunization. At the same time Aristotle presents a seminal perspective on abduction: the second part of the article considers the famous passage in Chapter B25 of Prior Analytics concerning ἀπαγωγή (“leading away”), also studied by Peirce. I contend that some of the current well-known distinctive characters of abductive cognition are already expressed, which are in tune with the EC-Model. By providing an illustration of the role of the method of analysis and of the middle terms in Plato's dialectic argumentation, considered as related to the diorismic/poristic process in ancient geometry – also, later on, emphasized by Proclus – I maintain that it is just this intellectual heritage which informs Aristotle' Chapter B25 on ἀπαγωγή. Even if, in general, Aristotle seems to sterilize, thanks to the invention of syllogistic theory, every “dialectic” background of reasoning, nevertheless in Chapter B25 he is still pointing to the fundamental inferential role in reasoning of those externalities that substantiate the process of “leading away” (ἀπαγωγή). Hence, we can gain a new positive perspective about the “constitutive” eco-cognitive character of abduction, just thanks to Aristotle himself. Finally, the paper presents an excursus on Aristotle's enthymemes from signs, disregarded by Peirce, but extremely important to stress the Aristotelian treatment of what I have called selective abduction. A forthcoming companion paper [35] will further deepen the EC-Model of abduction stressing stricter logical aspects: the first result will be that, contrarily to the classical logical view, relevance and plausibility in abductive reasoning have to be relativized and so the epistemologically embarrassing concepts of irrelevance and implausibility exculpated: they are not always offensive to reason.     

Linked arguments and the validity requirement

In this paper I demonstrate that most textbook accounts of the linked/convergent distinction fail to conform to the widespread intuition that all valid arguments ought to be classified as linked arguments. I also show that standard textbook accounts of linkage and convergence cannot provide a satisfactory treatment of fallacies of irrelevance and, due to their general insensitivity to the epistemic context in which arguments are offered, must be supplemented by subjective accounts of linkage and convergence which appeal exclusively to authorial beliefs and intentions.Drafts of this paper were read at the Ontario Philosophical Society meeting held at Trent University in October 1990 and the Central Division meeting of the American Philosophical Association held in Chicago in April 1991. I thank Trudy Govier, Hans Hansen and an anonymous referee for helpful and encouraging comments on various drafts.     

Naturalizing logic: Errors of reasoning vindicated: Logic reapproaches cognitive science

A complete revision of mainstream logic is an urgent task to be achieved. This revision will be able to bring logic into a creative rapprochement with cognitive science. This can be achieved by trying to do for logic what over forty years ago Quine and others attempted for epistemology. It is necessary to propose a “naturalization” of the logic of human inference. This paper deals with an examination of how the naturalization process might go, together with some indication of what might be achieved by it. To assist the reader in understanding the naturalization of logic I will take advantage of my own research on the concept of abduction, which vindicates the positive cognitive value of the fallacy of the affirming the consequent thanks to the so-called EC-model (Eco-Cognitive model), and of the recent book Errors of Reasoning: Naturalizing the Logic of Inference (2013) [86], by John Woods. While this paper certainly aims at promoting the research program on the naturalization of logic, it also further advocates the placement of abduction in the research programmes of logic, and stresses to what extent our contemporary philosophical and logical tradition is indebted towards Charles Sanders Peirce, a thinker often praised for his productivity but whose quality and importance are too often overlooked.