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Fallacy: An argument that tempts one to accept the conclusion as true, but does not really give a reason for doing so, or does not really give an adequate reason for doing so. Fallacy is the genus for each of the following definitions unless otherwise stated.

The fallacy of concluding some assertion is true because you want it to be true or you believe it.
Appeal to Majority (Appeal to Popularity, Appeal to Popular Opinion):
Concluding some claim is true because many people believe it.
Appeal to Emotion:
Concluding some statement is true because of some strong emotion such as anger, fear, or pity. It is stronger to use the more specific category when you can. For example, pointing out that a fallacy is "Appeal to Fear" is stronger than pointing out that it is "Appeal to Emotion".
Appeal to Force:
Concluding some proposition is true because of some threat.
Appeal to Authority:
Concluding some claim is true because some expert said it was, when the expert's expertise is in some other area.
Ad hominem:
Concluding some assertion is false because of some negative characteristic of the person making the claim. (Latin for "against the man")
Tu quoque:
A kind of ad hominem. Concluding that an accusation is false because the accuser is also guilty of the same fault. (Latin for "You too")
Poisoning the Well:
A kind of ad hominem. Concluding that irrelevant motives are the sole basis of an opponent's claim or argument, or that the claim must be false, when the person making the claim has irrelevant motives.
False alternative (Black and White Fallacy):
Concluding one alternative is true because another is unacceptable when there may be yet other alternatives.
Post hoc:
Concluding that some event caused another just because this event preceded the other.
Hasty Generalization:
Concluding that some general claim is true from an insufficient sample. For example, Paul made a million in 1968, so each of the Beatles made a million in 1968.
Concluding that some whole has some property just because a part of it does. For example, Paul made a million in 1968, so The Beatles (the band as a single entity) made a million in 1968. (This fallacy is not very believable because it is ludicrous to think that Paul would have gotten it all! But the example helps to distinguish this fallacy from Hasty Generalization.)
Concluding that some part has a property just because the whole does.
Begging the question (Circular Argument):
Concluding that some statement is true because you have used it as a premise. This differs subtly from subjectivism. In subjectivism your belief that the conclusion is true is taken as a reason for its truth. Whereas in Begging the Question, you simply assume the truth of the conclusion in your reasoning for it.
Complex Question:
A kind of Begging the Question. A question which has a hidden assumption such that answering the question in a straightforward way commits one to the assumption.
Question Begging Definition:
A kind of Begging the Question. Concluding that one can settle questions of substance by defining one's terms so that one wins -- stipulating a definition which begs the question.
Concluding that some claim is true by using two senses of a term as if they were really the same.
Appeal to ignorance:
Concluding that some claim is true because the opposite claim cannot be proved.
Illicit Contrast:
Concluding that a speaker would make a contrary claim about something other than what was spoken of. The fact that the speaker made a claim without bothering to make the same claim about something else is supposed to show that he or she would make the opposite claim about that something else.
Continuum (Fallacy of the Beard):
Concluding that any two things or states lying on the same continuum are basically the same. Because no sharp line can be drawn between any two adjacent points on a continuum, it is supposed to be impossible to make a genuine distinction between any two points no matter how far apart they might be.
Non sequitur:
Miscellaneous category for fallacies which do not fit a more specific category. (Latin for "does not follow")
Straw Person (Straw Man):
Concluding that one defeats an opponent's argument or position by defeating a caricature (exaggeration) of it.
Contrary to Fact Hypothesis:
Concluding that if some fact or facts had been different, one knows how some further facts would have been changed. Once we have left the realm of reality by supposing some facts to have been different, it becomes impossible to test the claim.
Special Pleading:
Concluding that some general principle or rule does not apply to one's own case or that an exception should be made for one's own case just because one's own case is special (well -- er -- at least to one's self).
Slippery Slope (Domino Fallacy, Thin Edge of the Wedge):
Concluding that some proposal would initiate an unstoppable series of consequences with some extreme result. The extreme nature of the result and some plausible steps in the series distracts one from noticing that each and every step has been claimed to be unstoppable.
Gambler's Fallacy:
Concluding that the probability or chance of some event is influenced by the past history of that event. The assumption is that probability or chance is a prescriptive force in the universe rather than a mere description or prediction.
Appeal to Tradition:
Concluding that some way of doing something is right or best because it was traditionally done this way.
Appeal to Novelty:
Concluding that some way of doing something is right or best because it is a new way to do this.
Genetic Fallacy:
Concluding that because some thing or some belief came about under unacceptable circumstances, it is still unacceptable, or if it came about under acceptable circumstances, it is still acceptable.