Ad hominem

From Academic Kids

An ad hominem argument, also known as argumentum ad hominem (Latin, literally "argument [aimed] at the person", but usually translated as "argument to the man"), is a logical fallacy that involves replying to an argument or assertion by addressing the person presenting the argument or assertion rather than the argument itself or an argument pointing out an inconsistency between a view expressed by an individual and the remainder of his or her beliefs.


Ad hominem as logical fallacy

A traditional, regular (fallacious) ad hominem argument was identified by Aristotle in his On Sophistical Refutations and has the basic form:

Regular Ad Hominem

  1. A makes claim B;
  2. there is something objectionable about A
  3. therefore claim B is false.

An inverted (fallacious) ad hominem argument was only identified as such more recently. Traditionally it would have been considered only an appeal to authority fallacy which it also is. The inversion can be seen as, and called as such when, an implication to "appeal to authority-lacking" regarding the opponent is obvious. Stated as such it is a better reflection of the bind the fallacymonger finds himself in, in presenting this fallacy, especially when self-referencing credentials as a critical point to an argument and, particularly when the claim is, to his own authority or, authority for its own sake. It has the basic form:

Inverted Ad Hominem

  1. A makes claim B; (C has made claim D or, at least it is implied she has.)
  2. there is something desirable about A, (Implied; which C lacks.)
  3. therefore claim B is true. (Implied; C's claim D is false.)

The first statement is called a 'factual claim' and is the pivot point of much debate. The last statement is referred to as an 'inferential claim' and represents the reasoning process. There are two types of inferential claim, explicit and implicit. Other positive arguments to the person are discussed under appeal to authority.

Ad hominem is one of the best-known of the logical fallacies usually enumerated in introductory logic and critical thinking textbooks. Both the fallacy itself, and accusations of having committed it, are often brandished in actual discourse. As a technique of rhetoric, it is powerful and used often, despite its lack of subtlety.


A regular ad hominem fallacy consists stating that a person and/or their argument is wrong to argue purely because of something discreditable/not-authoritative about the person or those persons cited by them rather than about the argument itself. The implication is that the person's argument and/or ability to argue correctly lacks authority. Merely insulting another person in the middle of otherwise rational discourse does not necessarily constitute an ad hominem fallacy. It must be clear that the purpose of the characterization is to discredit the person offering the argument, and, specifically, to invite others to discount his arguments. In the past, the term ad hominem was sometimes used more literally, to describe an argument that was based on an individual, or to describe any personal attack. But this is not how the meaning of the term is typically introduced in modern logic and rhetoric textbooks, and logicians and rhetoricians are widely agreed that this use is incorrect.

An inverted ad hominem fallacy consists of saying that someone's argument is correct and/or they are correct to argue at all purely because of something creditable/authoritative about the person or those persons cited by them rather than the argument itself. The implication is that the person need not even bother to defend against an attack on the soundness of his arguments because of this very credibility/authority. The other implication which can be seen as either leading to or following from the preceding implication, being that a potential opposing interlocutor lacks this very same credibility/authority (regular ad hominem). This "appeal to authority" and/or implied "appeal to authority-lacking" leaves the fallacymonger in a serious bind as it also implies a hidden premise which itself defeats his diversionary sub-argument about his own authority. This premise may then be 'granted' by any victim of this fallacy and her argument - at least regarding the fallacious sub-argument - is all but made.

Bind example: A recognizably credentialed professional logician (Fallacymonger) vs. a layperson (Fallacymongered): Note: In this example both the appeal to authority and authority-lacking are explicitly stated for the sake of clarity. In reality, the value of the introduction of the term Inverted Ad Hominem was to emphasise the often offensive yet subtle implication and nature of a fallacious Appeal to Authority.

Fallacymonger: "You are wrong to argue with me about matters of logic because I am an expert in this field. Because you lack this expertise yourself, I refuse to waste my time arguing with you at all about this matter."
Note: Expediency can be a good reason if actually based in reason to non-fallaciously "appeal to authority". One might reasonably expect the fallacymonger would have done better (diplomatically and logically) to excuse himself claiming "a lack of time - trust my expertise for now", rather than the antagonistic "a waste of time". Perhaps though, time was so short for him that he had not even enough time to reason this much.

Fallacymonger: "I will grant you this premise: That I would have to be a fool to argue that you are wrong in this regard simply because most, if not all, professional logicians agree that an 'appeal to authority' of this sort is a fallacy."

By granting this premise the fallacymongered acknowledges and forces the fallacymonger likewise to acknowledge A) he is already arguing with her and B) a willingness to argue from first principles if required, in order to make their respective cases. She must still present a sound argument, but so must the fallacymonger. Note that if he rejects her offer of the granted premise then he acknowledges, A) her right to cite his own peers to establish the fallaciousness of his argument or B) her right to ignore likewise the rules of logic, and so assume authority fallaciously herself (which of course leads to absurdity). But if he accepts the granted premise then, he has defeated himself undoubtedly - in his own diversion at least, for he acknowledges that he would have to be a fool himself to use his own expertise in this way.

Either way she has established her right to question his authority and his need to defend his authority logically. Note also that in this example the fallacymonger is also fallaciously begging the question by claiming his authority by appealing to his own authority and, has introduced a red herring by shifting the argument from being about; "matters of logic" to one about; themselves and his "expertise" and her "lack" thereof. It has become an argument about the argument which is understandable given that it was initially about "matters of logic". But his position became fallacious when he made it an argument about the arguers about the argument, even though the point of doing so seems to be about their status' as logicians or not. Regarding a logician's last argument it would seem that his/her status is only as relevant and valid as is her/his last argument.

This is of course a rather silly example, but unfortunately it is in principle a serious, common situation. One need only consider the circular arguments of someone defending his religion by invoking the authority of the God of that same religion to defend the authority of the church, bible and other artifacts of that very same religion which, in turn the authority of, are used to defend the authority of that same God and the artifacts themselves - not to mention his own authority. This is of course an inversion of the all too common regular (fallacious) ad hominem arguments of those who discredit non-religious views as corrupted and evil - for their very lack of religiosity, and claim those views are therefore invalid. (Inverted Ad Hominem is a term first coined by Layman at The Brights Forums ( A bright being a person whose worldview is naturalistic.)

Conversely, not all regular ad hominem attacks are insulting. "Paula says it is impossible for her to murder a man, but this is false because Paula has never lost her temper." Nor likewise are all inverted ad hominem defenses self flattering - "I say it is impossible for me to murder a man, and this is true because I often lose my temper."


Three traditionally identified varieties include ad hominem abusive, ad hominem circumstantial, and ad hominem tu quoque.

Ad hominem abusive

Ad hominem abusive (also called argumentum ad personam) usually and most notoriously involves merely (and often unfairly) insulting one's opponent, but can also involve pointing out factual but damning character flaws or actions. The reason that this is fallacious is that — usually, anyway — insults and even damaging facts simply do not undermine what logical support there might be for one's opponent's arguments or assertions.

Example 1: "Jack is wrong when he says there is no God because he is a convicted felon."

Example 2: Person A: "There is a God and archaeological records of the Middle East prove it." Person B: "Well, that's what I'd expect a fundamentalist Christian to say."

Ad hominem circumstantial

Ad hominem circumstantial involves pointing out that someone is in circumstances such that he or she is disposed to take a particular position. Essentially, circumstantial ad hominem constitutes an attack on the bias of a person. The reason that this is fallacious is that it simply does not make one's opponent's arguments, from a logical point of view, any less credible to point out that one's opponent is disposed to argue that way.

"Tobacco company representatives are wrong when they say smoking doesn't seriously affect your health, because they're just defending their own multi-million-dollar financial interests."

The Mandy Rice-Davies ploy, "Well, he would [say that], wouldn't he?" is a superb use of this fallacy.

It is important to note that the above argument is not irrational, although it is not correct in strict logic. This illustrates one of the differences between rationality and logic.

Ad hominem tu quoque

Ad hominem tu quoque (literally, "at the person, you too") could be called the "hypocrisy" argument. It occurs when a claim is dismissed either because it is inconsistent with other claims that the claimant is making or because the claim is about actions the claimant has engaged in, too.

"You say airplanes are able to fly because of the laws of physics, but this is false because earlier you said airplanes fly because of magic."
"You cannot accuse me of libel because what you do is libel as well."

The tu quoque form is often a specific kind of the two wrongs make a right fallacy.


This form of the argumentum ad hominem is a genetic fallacy and red herring, and is often but not necessarily an appeal to emotion. Argumentum ad hominem includes poisoning the well.

Valid Ad Hominem

The second form of the ad hominem was identified by John Locke in his An Essay Concerning Human Understanding, when he wrote that it was

to press a man with consequences drawn from his own principles or concessions. This is already known under the name of argumentum ad hominem.

For example, if an Atheist sent his children to a religious school on the ground that discipline or teaching was better there, an opponent might point out the inconsistency with the anti-religious atheism of his beliefs. Another form of the valid argument ad hominem can be applied to the testimony of a witness in a court-case. Ad hominem is fallacious when applied to deduction, and not the evidence (or premise) of an argument. Evidence may be doubted or rejected based on the source for reasons of credibility, but to doubt or reject a deduction based on the source is the ad hominem fallacy.

Premises discrediting the person can exist in valid arguments, when the person being criticized is the sole source for a piece of evidence used in one of his arguments.

  1. A committed perjury when he said Q
  2. We should not accept testimony for which perjury was committed
  3. therefore, A 's testimony for Q should be rejected

See also


de:Argumentum ad hominem es:Argumentum ad hominem fr:Ad hominem hu:Argumentum ad hominem nl:Ad hominem simple:Ad hominem he:אד הומינם pt:Argumentum ad hominem


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