*Some of these glossary definitions have been adapted and reproduced by permission of The American Heritage Dictionary of the English Language, Fourth Edition. Copyright © 2002 by Houghton Mifflin Company.

Fallacies of Cause

misidentification of the cause  An error that occurs in causal situations when identification of the cause and the effect are unclear.

post hoc ergo propter hoc  “After it, therefore because if it”; refers to situations in which, because two things occur close together in time, an assumption is made that one causes the other.

questionable cause  A fallacy that occurs when someone presents a causal relationship for which no real evidence exists.

slippery slope  A causal fallacy that asserts that one undesirable action will inevitably lead to a worse action, which will necessarily lead to a worse one still, all the way down the slippery slope to a terrible disaster at the bottom.

Fallacies of Relevance

appeal to authority  A type of fallacious thinking in which the argument is intended to persuade through the appeal to various authorities with legitimate expertise in the area in which they are advising.

appeal to fear  An argument in which the conclusion being suggested is supported by a reason invoking fear and not by a reason that provides evidence for the conclusion.

appeal to flattery  A source of fallacious reasoning designed to influence the thinking of others by appealing to their vanity as a substitute for providing relevant evidence to support a point of view.

appeal to ignorance  An argument in which the person offering the conclusion calls upon his or her opponent to disprove the conclusion.  If the opponent is unable to do so, then the conclusion is asserted to be true.

appeal to personal attack  A fallacy that occurs when the issues of the argument are ignored and focus is instead directed to the personal qualities of the person making the argument in an attempt to discredit the argument.  Also referred to as the ad hominem argument (“to the man” rather than to the issue) or “poisoning the well.”

appeal to pity  An argument in which the reasons offered to support the conclusions are designed to invoke sympathy toward the person involved.

appeal to tradition  A misguided way of reasoning that argues that a practice or way of thinking is “better” or “right” simply because it is older, traditional, or has “always been done that way.”

bandwagon  A fallacy that relies on the uncritical acceptance of others’ opinions because “everyone believes it.”

begging the question  A circular fallacy that assumes in the premises of the argument that the conclusion about to be made is already true.  Also known as “circular reasoning.”

red herring  A fallacy that is committed by introducing an irrelevant topic in order to divert attention for the original issue being discussed.  Also known as “Smoke Screen” and “Wild Goose Chase.”

straw man  A fallacy in which a point of view is attacked by first creating a “straw man” version of the position and then “knocking down” the straw man created.  The fallacy lies in that the straw man does not reflect an accurate representation of the position being challenged.

two wrongs make a right  A fallacy that attempts to justify a morally questionable action by arguing that it is a response to another wrong action, either real or imagined.