ad hominem

"Against" the man, To the man, Argumentum ad hominem

This is probably the commonest fallacious argument of all in debates about emotion-laden issues – attacking the messenger.

Addressing the qualities or qualifications of "the man" might not be fallacious if "the man" clearly displays prejudices in his/her opinion. The possibility always remains that the conclusion drawn by a highly biased debater may be the correct conclusion. However, arguments that display prejudices are automatically suspect.

Equally, the conclusions of an arguer who is not an expert in the area under discussion may be correct, but such an arguer would need to make the premises and logic of his/her argument quite clear in order to compensate for the possibility that his/her argument is not authoritative. Nevertheless, to question the messenger's expertise is not necessarily an ad hominem fallacy, though it is an ad hominem - a legitimate ad hominem.

On the other hand, tTo call the opposing debater 'an ignorant idiot' might feel justified in view of one's frustration with his obdurate denial of one's own version of reality, but it is not a good argument against his or her argument, or his or her conclusion. He or she might be correct, or you might both be mistaken. However, such an assessment ought to be based on the merits of his or her, or your argument.

Fallacious ad hominems employ a variety of attacks: directly abusive, circumstantial, and accusations of "poisoning the well".

irrelevance

Irrelevance crops up in many arguments:

When the argument itself seems logical, yet the conclusion is not relevant to or supported by the line of argument, then the fallacy is ignoratio elenchi (ignorance of the issue). Such problems may occur when the arguer is not responding to the actual question posed.

When the line of argument is off-target for the topic under discussion and distracts from the real topic, then the arguer has tossed a red herring into debate in order to create a smokescreen.

Irrelevant attacks on the arguer or cited authority are ad hominem fallacies. However, if the "authority" who/that has been cited fails as a legitimate authority on one or more grounds, then disputing the expertise or credibility of that person/reference is not an ad hominem fallacy.

Logic and emotion are often at odds. When irrelevant appeals to emotion are incorporated into arguments, then the conclusions drawn by that argument become suspect if the emotion is not specifically related to the topic. To argue that a person will probably enjoy eating chocolate is not necessarily unfounded, though it would not be relevant to discussion about chicken pot pie.

tu quoque

Tu quoque, You too, You also, You're another

An arguer commits a tu quoque fallacy when, in the context of an attack within an argument, the arguer contends that the opponent is behaving is some way in which the arguer is also behaving and it is implied or explicitly stated that the opponent is incorrect to do so.

The tu quoque fallacy is a form of argumentum ad verecundiam combined with the two wrongs make a right fallacy:

Common creationist and proid tu quoque fallacies also involve equivocation, which takes advantage of the ambiguities of vernacular terminology:

"Science is dogma", "evolution is just a theory, so 'id' theory is science and is equally valid", "science is just a matter of faith". These are tu quoques because evolutionists state that religion beliefs are expressed in dogma, idism is not a scientific theory, and religion truly is expected to be a matter of Faith. Such arguments are often employed to divert discussion away from the real point of discussion – they are red herrings. These tu quoques will be addressed in the deliberate ambiguities post.

"Darwinist efforts to use the courts, the media and academic tenure committees to suppress dissent and stifle discussion are in fact fueling even more dissent and inspiring more scientists to ask to be added to the list." [s]

Considering the promises made in The Wedge Document, this statement is glaring example of a tu quoque fallacy – a "you too!" fallacy. The statement was made by Dr. John G. West, associate director of Discovery Institute's Center for Science & Culture as justification for the fallacious appeal to authority made in compiling and publishing the Scientific Dissent From Darwinism list.

"According to West, it was the fast growing number of scientific dissenters which encouraged the Institute to launch a website -- http://www.dissentfromdarwin.org/ -- to give the list a permanent home." [s]

This may, or may not be the reason for the website. It could equally be that scientists known to have strong religious convictions were approached by the DI, and that the website was launched to advertise the list. Such behavior would be well within the rights of those wishing to promote the 'id' platform. The point is that the list was compiled specifically to sway public and school board opinion, and the statement was made to the media, so the statement is a tu quoque.

Tu quoque statements are along the lines of an abusive husband's saying that he would not have beaten his wife if she had not burnt the toast. Equally, if the wife said that she would burn the toast again because her husband had beaten her, she would be committing a less egregious tu quoque action.