logical fallacy

Ad Hominem

Attacking the person making the argument, rather than the argument itself, when the attack on the person is completely irrelevant to the argument the person is making

Straw Man

Substituting a person's actual position or argument with a distorted, exaggerated, or misrepresented version of the position of the argument.

Appeal to Ignorance

The assumption of a conclusion or fact based primarily on lack of evidence to the contrary. Usually best described by, "absence of evidence is not evidence of absence."

False Dilemma ("either/or")

When only two choices are presented yet more exist, or a spectrum of possible choices exists between two extremes. False dilemmas are usually characterized by "either this or that" language, but can also be characterized by omissions of choices. Another variety is the false trilemma, which is when three choices are presented when more exist

Slippery Slope

When a relatively insignificant first event is suggested to lead to a more significant event, which in turn leads to a more significant event, and so on, until some ultimate, significant event is reached, where the connection of each event is not only unwarranted but with each step it becomes more and more improbable. Many events are usually present in this fallacy, but only two are actually required -- usually connected by "the next thing you know..."

Circular Argument

A type of reasoning in which the proposition is supported by the premises, which is supported by the proposition, creating a circle in reasoning where no useful information is being shared. This fallacy is often quite humorous

Hasty Generalization

Hasty generalizations arise when we illegitimately generalize from a nonrepresentative sample. They are the source of many stereotypes

Red Herring

Attempting to redirect the argument to another issue to which the person doing the redirecting can better respond. While it is similar to the avoiding the issue fallacy, the red herring is a deliberate diversion of attention with the intention of trying to abandon the original argument

Tu Quoque (a form of Ad Hominem)

an accused person turns an allegation back on his or her accuser, thus creating a logical fallacy

Causal Fallacy

Assuming a single cause or reason when there were actually multiple causes or reasons

Appeal to Authority

Insisting that a claim is true simply because a valid authority or expert on the issue said it was true, without any other supporting evidence offered. Also see the appeal to false authority

Post Hoc Ergo Propter Hoc (a form of Causal Fallacy)

The argument offers an explanation, based on a temporal ordering of the events, that confuses co-occurrence with causality: A happened just before B, so A caused B

*Begging the Question (a form of Circular Reasoning)

Any form of argument where the conclusion is assumed in one of the premises. Many people use the phrase "begging the question" incorrectly when they use it to mean, "prompts one to ask the question". That is NOT the correct usage. Begging the question is a form of circular reasoning

Guilt By Association (a form of Ad Hominem)

When the source is viewed negatively because of its association with another person or group who is already viewed negatively.

Ad Populum

appeal to the popularity of a claim as a reason for accepting it

False Analogy

When an analogy is used to prove or disprove an argument, but the analogy is too dissimilar to be effective, that is, it is unlike the argument more than it is like the argument

Appeal to Tradition

Using historical preferences of the people (tradition), either in general or as specific as the historical preferences of a single individual, as evidence that the historical preference is correct. Traditions are often passed from generation to generation with no other explanation besides, "this is the way it has always been done"—which is not a reason, it is an absence of a reason

No True Scotsman

one's belief is rendered unfalsifiable because no matter how compelling the evidence is, one simply shifts the goalposts so that it wouldn't apply to a supposedly 'true' example. This kind of post-rationalization is a way of avoiding valid criticisms of one's argument

Bandwagon

the popularity of an idea has absolutely no bearing on its validity