Informal logic

Informal logic, or nonformal logic, is the study of a posteriori arguments as opposed to the technical and theoretical study of mathematical logic. This part of logic is mainly dedicated to differentiating between correct and incorrect ways in which language and everyday thought are developed, especially the study of the processes to obtain conclusions from given information, regardless of its logical form. Part of that human thought and language is often incorrect, or biased. It emerged in the 1970s as a subfield of philosophy. The first work to talk about this discipline was Logic and Contemporary Rhetoric (1971) by Howard Kahane.

Informal fallacies

Informal fallacies are a type of incorrect argument in natural language. The source of the error is not only due to the form of the argument, as is the case with formal fallacies, but can also be due to its content and context. Fallacies, despite being incorrect, generally appear to be correct and therefore can seduce people into accepting and using them. These misleading appearances are often connected with various aspects of natural language, such as ambiguous or vague expressions, or with the assumption of implicit premises instead of making them explicit.

Traditionally, a large number of informal fallacies have been identified, such as the fallacy of equivocation, the fallacy of amphibology, the fallacy of composition and division, the false dilemma, the question of principle, the ad hominem argument, and the ad ignorantiam argument.. There is no general agreement on how the various fallacies should be grouped into categories. One approach sometimes found in the literature is to distinguish between fallacies of ambiguity, which are rooted in ambiguous or vague language, fallacies of presumption, which involve false or unwarranted premises, and fallacies of relevance, in which the premises are not correct. are relevant to the conclusion despite appearances to the contrary.

The traditional approach to fallacies has received much criticism in contemporary philosophy. This criticism is usually based on the argument that the alleged fallacies are not fallacious at all, or at least not in all cases. To overcome this problem, alternative approaches of how to conceive of arguments and fallacies have been proposed. These include the dialogic approach, which conceives of arguments as plays in a dialogue game whose goal is to rationally persuade the other person. This game is governed by several rules. Fallacies are defined as violations of dialogical rules that impede the progress of the dialogue. The epistemic approach constitutes another framework. His central idea is that arguments play an epistemic role: they aim to broaden our knowledge by providing a bridge from beliefs already justified to beliefs not yet justified. Fallacies are arguments that do not achieve this goal by breaking a rule of epistemic justification. In the Bayesian approach, epistemic norms are given by the laws of probability, which our degrees of belief should follow.The study of fallacies aims to provide an explanation for evaluating and criticizing arguments. This involves both a descriptive account of what constitutes an argument and a normative account of what arguments are good or bad. In philosophy, fallacies are often considered a form of bad argument and are discussed as such in this article. Another conception, more common in non-academic discourse, sees fallacies not as arguments but rather as false but popular beliefs.

Critics

Some hold the view that informal logic is not a branch or subdiscipline of logic, or even that there can be no such thing as informal logic. Massey criticizes informal logic on the grounds that it has no theory that sustains it. Informal logic, he says, requires detailed classification schemes to organize it, like the underlying theory that is provided in other disciplines. He maintains that there is no method of establishing the invalidity of an argument other than the formal method, and that the study of fallacies may be more of interest to other disciplines such as psychology than to philosophy and logic.