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What Are Fallacies of Logic?

Angela Farrer
Angela Farrer

Fallacies of logic are mistakes in reasoning that frequently lead to misconceptions and conclusions that are drawn from incomplete or inaccurate information. When this incorrect thinking is communicated to others, the speaker often commits a logical fallacy that related evidence does not support. Fallacies of logic usually fall into various sub-categories based on which specific part of the statement or argument has the error in reasoning. A fallacy can be formal, informal, or based on assumptions that do not create a complete picture of the facts surrounding the issue at hand.

Common formal fallacies include various non sequiturs in which an argument's conclusion does not logically follow at least one of its supporting statements known as premises. The specific errors in these fallacies of logic can be found in the lack of clear connection between the premises and conclusion. A formal fallacy in the form of a non sequitur frequently leaves a listener puzzled about how exactly a premise statement leads to the fallacious conclusion. The topics of each statement often appear to have little to do with one another according to various established rules of logic. Formal fallacies are also sometimes known as fallacies of argument because they often contain noticeable errors in deductive reasoning.

Woman holding a book
Woman holding a book

Fallacies of logic can also be designated as informal, meaning that at least one mistake in thinking stems from the specific statement content rather than the whole structure of the certain given argument. Informal logic is connected to inductive reasoning that separates specific supporting statements from a generality. These fallacies of reasoning usually offer faulty assumptions within the supporting premises, and these assumptions can sometimes be more subtle than those in other erroneous statements. Informal fallacies of logic often include incomplete and inconsistent criteria for drawing a concluding statement from a more general idea.

A logical fallacy can result from other mistakes, such as flawed generalizations and arguments that address tangential issues rather than the original argument in question. Too-quick conclusions without consideration of all the facts often result from broad generalizations. These fallacies can also sometimes entail deliberately ignored facts that do not support a particular agenda. A fallacy that serves as a distracting argument is often called a "red herring" because it pulls the listeners' attention to unrelated and usually irrelevant information. Categories of red herring fallacies frequently appeal to listeners' emotional, rather than logical, tendencies such as fear or vanity.

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