Filosofia Das Logicas

by Susan

A relação entre a lógica e a linguagem é um dos principais pontos deste livro. O estudo de termos como validade, conectivos sentenciais, quantificadores, termos singulares, sentenças, enunciados, teorias da verdade, paradoxos, lógica modal e polivalente ocorre de uma maneira que privilegia a pluralidade de interpretações. Dessa maneira, são gerados problemas e perguntas - nem sempre respondidas, mas invariavelmente instigantes - que permitem os professores, estudantes de lógica e, de maneira geral, a todos aqueles interessados na dinâmica da argumentação, ampliar a sua visão do assunto, estimulando o diálogo com outras áreas do conhecimento.

Genres: Philosophy, Logic, Nonfiction

356 pages, Paperback

First published July 27, 1978

Reviews

[path · Rating 4 out of 5]

Quite a good overview of what is at stake and at issue in philosophical discussions of logic. Above all, Haack clearly shows that traditional, formal logic is not quite the language of the universe, one by which all truth may be derived. Logic is a tool designed to do a job, which it more or less does well and consistently. However, it is important to recognize that logic is normative (i.e., defines how valid arguments should look) and it sets the boundaries about what can be conclusively reasoned. As a structured technique for reasoning, logic is also a way of making reasoning visible and shareable and for making us accountable to others for the conclusions that we reach. For these reasons, logic is supposed to be a system of thinking that is applicable across and capable of structuring different domains of content. But in adapting logic to variations of content (about which our experiences, intuitions, certainty, and situated access differ) applies stress to formal logic that require the creation of extended logics, restricted logics, and fuzzy logics.

Through sections on inductive/deductive/abductive reasoning and through a great chapter on theories of truth, including correspondence, coherence, pragmatic, semantic, and redundant truth models, Haack shows that the truth conditionality of statements derived from logic are problematic. For example a correspondence theory of truth, which holds that true statements are those that correspond to the world, becomes problematic if we start to think about what “correspond” means. Does it mean isomorphic correspondence in that there is a similarity or resemblance to reality? Does it means that there is agreement? Does it mean that there is a direct referential link between a thing we talk about and a thing in the world? And aren’t there things that we talk about as if they were real, like The Economy, which is really just an abstraction and a set of conventional and functionally related statements and observations about data points that we take, holistically, to be a thing in the world about which we can make reasoned assertions? In that sense, The Economy looks true because is corresponds to reality but we allow that correspondence because we also tacitly accept that The Economy is a set of relatively stable statements that are coherent in their association. There are then similar breakdowns between other models of truth and the logics associated with them. And what models of logic are most appropriate for these models of truth?

I appreciate the thinking that has gone into the logics that Haack identifies but I do wonder if the complexity of the situations and positions and topics that models of logic are attempting to describe are really making logic complex to the point that, to the extent to which we can even understand a system of logic, it may fit and work as an explanation of reason but the model becomes so complex and specialized in its use that it stops being a useful and accessible tool for mediating reason and guiding reason intuitively. Another way to put this is that a basic Aristotelian logical form like modus ponens (i.e., [1] If P then Q; [2] P; [3] therefore Q) makes intuitive sense; it guides intuition in the way that some of the more complex, multivalent logics and fuzzy logics that Haack discusses are not. They are complex models of reasoning and perhaps accurate but are they generative? Are they better at describing reason than guiding it? It certainly seems so.

There is a lot to appreciate in this book, not the least of which is Haack’s writing, which is really superb, clear, and direct. I also appreciate Haack’s summary of the problems and challenges of logic to underscore that logic is a tool designed to correspond to a particular way of organizing and categorizing things in the world and to accommodate science and the regularity with which we are able to do science. But there are gaps and paradoxes and situations in reasoning when we get too far away from what can be experienced, intuited, referenced, predicted, and proven. Logic cannot critique itself and so a book like this is valuable for pointing out where systems of logic work and where we just accept that they work because we overlook limitations of scope, generalizability, contingency, and uncertainty.

[AC · Rating 5 out of 5]

Excellent discussion of the principal theories of Truth - correspondence (Plato); consistency (James); and Tarski's semantic theory of Truth.

[John Reis · Rating 5 out of 5]

This was a very informative book. It really is a book on the history of the philosophy of language as well. This made me come to the conclusion that the philosophy of language was born out of the difficulties Frege had with building a formal language that allowed syntax, but omitted semantics.

Haack does at the end take up the issue of the legitimacy of classical logic by discussing the place of the newer logics. Are they rivals or additions to classical logic? Various thinkers have differing views. Haack takes a pluralistic view. I would take the same position, although I do not know if we have adequately discussed the scope of logic to draw the conclusion that it is possible to create other logics for specific purposes. Logic, as Aristotle formulated it was for the analysis of multi part arguments for various positions on classes of things. Its original working material was assertions. So, can logic be extended beyond assertions to predictions, commands and other forms of speech? Haack does not address this issue specifically.

[Red John · Rating 5 out of 5]

This is a great book that covers classical logic as well as its extensions such as modal logic. An extremely interesting, philosophical examination of logic and related topics.

[Paal Skjørten Kvarberg · Rating 5 out of 5]

Comprehensive in scope, and fair in discussion. Also has sensible takes on the problems herself. A good introduction to the philosophy of logic.