(1) The person's character is attacked. (2) the person's circumstances are noted. (3) the person does not practise what is preached. This takes many forms. For example, the person's character, nationality or religion may be attacked. Alternatively, it may be pointed out that a person stands to gain from a favorable outcome. Or, finally, a person may be attacked by association, or by the company he keeps. There are three major forms of Attacking the Person: 1) ad hominem (abusive): instead of attacking an assertion, the argument attacks the person who made the assertion. 2) ad hominem (circumstantial): instead of attacking an assertion the author points to the relationship between the person making the assertion and the person's circumstances. 3) ad hominem (tu quoque): this form of attack on the person notes that a person does not practice what he preaches, in effect, "look who's talking".

Examples


Ad hominem abusive: "According to supporters of capital punishment, the death penalty is an effective deterrent against murder. This is nonsense. These people are not interested in deterrence at all.
They want vengeance pure and simple. They suffer from a kind of bloodlust; they are people who flock to see Dirty Harry movies. They get turned on by the thought of shooting up the bad guys." (Hughes
& Lavery, Critical Thinking, p. 152.)


"This tweet really riled men up. Stop mansplaining to me in the replies." Charges of "mansplaining" is a recent example of "poisoning the well" by shaming someone for offering an opinion, argument, or explanation in virtue of them being male.


Ad hominem circumstantial: In the current "Climate Change" debate, accusations of dishonest motives are rife. Advocates of catastrophic climate change, for example, are accused of 1) being "watermelons", truly motivated by socialist ideals, seeking to transfer power from private enterprise to government regulation, as well as 2) merely trying to tap into the considerable financial funding available for research favorable to climate change "alarmism". Skeptics, often referred to disparagingly as "deniers", are similarly tarred as being shills for the energy industry, likewise motivated by filthy lucre rather than the truth of the matter. When these idealogical or pecuniary interests are taken to discredit arguments for or against catastrophism, we have a case of ad hominem circumstantial.


Ad hominem circumstantial: "Of course academics argue in favour of the proposed expansion of university education: the more aspiring graduates there are, the more job opportunities there are for people like them." (Bowell & Kemp, Critical Thinking, p. 135.)


Ad hominem circumstantial: "It is true that several college professors have testified that these hallucinogenic drugs are harmless and nonaddictive, but these same professors have admitted to taking drugs themselves. We should certainly disregard their views."

Engel, Soldan, and Durand, The Study of Philosophy, p. 143.

Ad hominem tu quoque: "Majority member Joe C. is under fire for using public funds to pay for more than $44,000 in expenses. Minority members accused the majority floor leader of having one standard in opposition and quite another standard n government. In defense of Joe C., the majority floor leader pointed out that a minority member (while in the previous majority) had himself been questioned about his expenses, including out of state travel expenses."

Tindale, Fallacies and Argument Appraisal, p. 95.

Ad hominem tu quoque: "Far too much has been made over the CIA's espionage abroad. Other countries are just as deeply engaged in spying as we are."
(Engel, Soldan and Durand, The Study of Philosophy, p. 143.)


Ad hominem tu quoque: "Those Islamists and their apologists who argue for 'religious toleration' are arrogantly dishonest. They ignore the fact that more than 100 mosques already exist in New York City. Meanwhile, there are no churches or synagogues in all of Saudi Arabia. In fact no Christian or Jew can even enter Mecca. And they lecture us about tolerance. If the people behind the Cordoba House were serious about religious toleration, they would be imploring the Saudis, as fellow Muslims, to immediately open up Mecca to all and immediately announce their intention to allow non-Muslim houses of worship in the Kingdom." (Newt Gingrich, "Statement on the Proposed 'Cordoba House' Mosque near Ground Zero", newt.org, accessed July 21, 2010.)


Ad hominem abusive: "The Democrats juxtaposed a child plucking the petals from a daisy with the explosion of a bomb as Lyndon Johnson extolled the value of loving one another. A young girl is picking daisies in a field. 'Four, five, six, seven,' she says. An announcer's voice (actually the voice used to count down the space launches at Cape Canaveral) begins an ominous count. "Ten, nine, eight...' At zero the camera has closed on the child's eye. A nuclear bomb explodes. Lyndon Johnson's voice is heard: 'These are the stakes. To make a world in which all of God's children can live. Or to go into the darkness. We must either love each other. Or we must die.' Until the tag line appears, that ad has no explicit partisan content. 'Vote for President Johnson on November 3. The stakes are too high for you to stay at home." (Jamieson, Dirty Politics, pp. 54-6.) While no explicit ad hominem is volleyed in this famous political ad, the implication is clear that Johnson's opponent, Barry Goldwater is trigger-happy, and thereby a threat to one's family. The Slippery Slope fallacy is applicable here too.


Ad hominem abusive: "He thrives at the lectern, where his powers of rhetoric and recall enable him to entertain an audience, go too far, and almost get away with it. ... Creationists are 'yokels,' Pascal’s theology is 'not far short of sordid,' the reasoning of the Christian writer C. S. Lewis is 'so pathetic as to defy description,' Calvin was a 'sadist and torturer and killer,' Buddhist sayings are 'almost too easy to parody,' most Eastern spiritual discourse is 'not even wrong,' Islam is 'a rather obvious and ill-arranged set of plagiarisms,' Hanukkah is a 'vapid and annoying holiday,' and the psalmist King David was an 'unscrupulous bandit.' ... In a curious rhetorical tic, Hitchens regularly refers to people whom he wishes to ridicule by their zoological class. Thus the followers of Muhammad are 'mammals,' as is the prophet himself, and so are the seventeenth-century false messiah Sabbatai Zevi and St. Francis of Assisi; Japan’s wartime Emperor Hirohito is a 'ridiculously overrated mammal,' and Kim Il Sung, the father of North Korea’s current dictator, is a 'ludicrous mammal.' Hitchens is trying to say that these people are mere fallible mortals; but his way of saying it makes him come across as rather an odd fish."

Gottlieb, "Atheists with Attitude" in The New Yorker, May 21, 2007.

Ad hominem abusive: "I did some research on this last night and found that the ones who accused Mike of lying were the 'Jesus People USA' and according to their website they are a group of 500 who all live at the same address and live in a commune! How's that for sane? (Can we say Waco?) And, what a surprise, the Cornerstone magazine was published by them. Hmm." (Discussion at Wikipedia)

Critique

Identify the proposition in question and note that it is either true or false irrespective of the character or circumstances of its proponent.

Commentary

On Ad Hominem Abusive

"The abusive type of ad hominem argument occurs where one part in a discussion cirticizes or attempts to refute the other party's argument by directly attacing that second party personally. This argument has the form, 'My opponent here is a bad person; therefor (the audience) should not accept his argument.' In this type of arguemtn, the attack is centrally on the character of the opponent. Quite often it is bad character for veracity that is the focus of the attack." (Walton, Ad Hominem Arguments, p. 2.)

On the near inevitable effect of abusive Ad Hominems:

"The introduction of an ad hominem argument into a dispute represents the personalization of the dialogue. Quite expectedly and characteristically, therefore, the use of the ad hominem leads both to an intensifying of personal involvement in a discussion and to a heightening of emotions. Indeed, one of the main problems of using an ad hominem argument is that it has a way of making a discussion into a quarrel. Once the ad hominem is used, it is often used by the attacked person again, in tu quoque fashion, and as personalization of the argument deepens, it becomes difficult to turn back to a less personalized discussion of the issue. In fact, too often what happens is that the original critical discussion deteriorates into an eristic dialogue or species of "verbal combat" where critical restraint is left behind, and the only aim is to "hit out" verbally to injure the other party." (Walton, The Place of Emotion in Argument, p. 192.)

On Ad Hominem Circumstantial

This is a sub-species of the ad hominem fallacy and occurs when someone's argument in favour of doing or believing something is discounted on the grounds that they would allegedly benefit from our
doing or believing it.

Tracy & Bowell, Critical Thinking, p. 135.

Tindale suggests that while the use of a circumstantial ad hominem fallacy may not defeat an argument, the conflict of interest it points out is worth taking into consideration and warrants a closer look at the argument itself. This is especially true, as is often the case, when an argument is made by someone who has been called upon as an authority. For example, an elected city council has to make decisions on many issues where they are not themselves experts, and relevant arguments may be opaque to non-specialists, necessitating a level of trust.

"Locke says the argument as one in which a person is pressed with 'consequences drawn from his principles or concessions.' This is to look not so much at a person's character as his particular circumstances relative to the issue in question. He may be in a position to benefit in some way from the way the case is resolved. Thus, bringing such a vested interest to light is to question an individual's position or argument for circumstantial reasons. The city planner who advocates building a new road along route A rather than route B may have her judgment questioned if an opponent points out that the planner happens to live along route B. The planner may present a very good case for why the road should follow route A, so an evaluator would have to consider carefully the degree to which the circumstantial factor should play a role in the reasoning."

Tindale, Fallacies and Argument Appraisal, p. 94.

So, it is not always clear that the ad hominem circumstantial is out of place. For example, after providing an independent argument for the relative safety and security of the Mac OS vis-à-vis Windows, to top it off, Daniel Eran Dilger notes:

"They are not the same, and only a liar would keep suggesting that Mac and Windows users face the same dangers and threats. If you’re paying attention, you’ll notice that those who keep suggesting this almost always work for an anti-virus company working to make money off of Mac users. This shouldn’t require any help in dot connection." ("Are Macs more Safe than Secure? No" at RoughlyDrafted.com, May 16, 2009.)

The intricacies intrinsic to the issue of software security are beyond the ken of the average computer user, and Dilger's note serves to raise their suspicion towards claims hoped to be taken at face value. Again, vested interests do not decide the issue, but motivate skepticism and hopefully a closer look. There is a real danger here, however. Everyone has to make a living, and it is usually the case that the experts in a particular field are able to do their specialized work because they are remunerated for it. As always, the only recourse to determine the matter for one's self is to look closely at the argument apart from who is making it.

[Add note about "prejudicial witnesses".]

On Ad Hominem tu quoque

"In common with ad hominem fallacies, the tu quoque ('you too') fallacy occurs when we make unwarranted connections between a person's alleged lack of credibility and the strength of their argument. Here
the alleged attack of credibility ensues specifically from their being hypocritical: and inconsistency between the arguer's actions and their claims. The fallacy is committed when we: reject a person's claim that a behaviour or proposal should be refrained from or discarded on the grounds that they themselves practise that behaviour; or when we reject a person's claim that a behaviour or proposal should be adopted on the grounds that they fail to follow it themselves."

Tracy & Bowell, Critical Thinking, p. 137.

"If I am accused of extravagance I do not answer the accusation though I may silence the accuser by providing that he himself is no better; if my opinions are attacked I cannot substantiate them by replying that my opponent once held them himself. Such a retort I may have a perfect right to make, but I have no right to confuse it with a vindication of my own position. (Aikins, The Principles of Logic, p. 202.)

On Poisoning the Well

The expression goes back to the Middle Ages, when waves of anti-Jewish prejudice and persecution were common. If a plague struck a community, the people blamed it on the Jews, whom they accused of 'poisoning the wells.' In the poisoning-the-well fallacy an attempt is made to place the opponent in a position from which he or she is unable to reply. This form of the fallacy was identified by John henry Cardinal Newman, a nineteenth century British churchman, in one of his frequent controversies with the clergyman and novelist Charles Kingsley. During the course of their dispute, Kingsley suggested that Newman, as a Roman Catholic priest, did not place the highest value on truth. Newman protested that such an accusation made it impossible for him, or for any Catholic, to state his case. For how could he prove to Kingsley that he had more regard for truth than for anything else if Kingsley presupposed that he did not? Kingsley had automatically ruled out anything that Newman might offer in defense. Kingsley, in other words, had poisoned the well of discourse, making it impossible for anyone to partake of it.

Engel, The Study of Philosophy, 2002, p. 153.

Afterall.net circles around contentious issues of faith and reason. This strategy of poisoning the well is widespread in these debates. Skeptics often suggest that anyone who makes space for faith in their worldview has thereby demonstrated their disregard for the tools of reason, or that having committed to particular theological presuppositions, one is unable to follow reason where it leads. Such accusations are no doubt accurate in many cases, but I would argue, not in every case, and not necessarily.

An effective poisoning-the-well ad hominem is to set the issue in the framework of an existing or potential group quarrel, at the same time suggesting that the other side is inevitably biased because of membership in the opposed group. The technique in this type of argumentation is to imply that those opposed to one's own point of view are so heavily and hopelessly biased by their own prejudice or fanatical attitude that their opinions can be disregarded altogether, no matter what they might say. This ad hominem move, if successful, cuts off all possibility of further critical discussion of the issue in question. There is no room left for looking at the arguments of the other side on their merits, or on good evidence, because the presumption is that the other side must be quarreling. Therefore, they are not open-minded and honest participants in a critical discussion. They are dogmatic, eristic arguers whose arguments can be rejected in advance as biased and one-sided.

Walton, The Place of Emotion in Argument, pp. 236-7.