Logical fallacies

In philosophy, the term logical fallacy properly refers to a formal fallacy: a flaw in the structure of a deductive argument which renders the argument invalid. However, it is often used more generally in informal discourse to mean an argument which is invalid for any reason, and thus encompasses informal fallacies – those which are invalid for reasons other than structural flaws, such as an error in the premises – as well as formal fallacies.

The presence of a formal fallacy in a deductive argument does not imply anything about the argument's premises or its conclusion. Both may actually be true, or even more probable as a result of the argument (e.g. appeal to authority), but the deductive argument is still invalid because the conclusion does not follow from the premises in the manner described. By extension, an argument can contain a formal fallacy even if the argument is not a deductive one; for instance an inductive argument that incorrectly applies principles of probability or causality can be said to commit a formal fallacy.

Recognizing fallacies in everyday arguments may be difficult since arguments are often embedded in rhetorical patterns that obscure the logical connections between statements. Informal fallacies may also exploit the emotions or intellectual or psychological weaknesses of the audience. Having the capability to recognize fallacies in arguments will hopefully reduce the likelihood of such an occurrence.

A different approach to understanding and classifying fallacies is provided by argumentation theory; see for instance the van Eemeren, Grootendorst reference below. In this approach, an argument is regarded as an interactive protocol between individuals which attempts to resolve a disagreement. The protocol is regulated by certain rules of interaction and violations of these rules are fallacies. Many of the fallacies in the list below are best understood as being fallacies in this sense.

Common examples
''For a list of types of formal and informal fallacy, as well as examples of fallacious arguments, see Fallacy. For a concise list of "appeal to" fallacies, see Appeal (disambiguation).''
 * Ad hominem
 * Affirming the consequent
 * Appeal to the majority
 * Argument from ignorance
 * Begging the question
 * Correlation implies causation
 * Equivocation
 * Post hoc ergo propter hoc
 * Straw man