Ad hominem is a Latin phrase meaning ‘to the man’, and it is the label for a particular kind of fallacy in Critical Thinking. Sometimes this is known as “playing the man, not the ball”. It consists in an irrelevant appeal to the nature of a person to either support or dismiss their argument (usually to dismiss it). The following video gives some different types and examples:

The following video gives a great example from a US election campaign.

Here the argument is against Dan Quayle, comparing him unfavourably to Jack Kennedy even though he never claimed to be like Jack Kennedy, but merely compared his degree of experience to that of Kennedy. This is a kind of reversed guilt by association, dismissing Quayle’s argument about his suitability to stand in for the president through an irrelevant personal comparison.

However, there are some circumstances where it is relevant and appropriate to judge an argument by the character of the arguer. This is obviously the case if that person’s character is the subject of the discussion. So, if, for example, someone boasted in a job interview that they would make a good manager because they used to captain their school football team, it would not be ad hominem to respond that their criminal record undermined this claim by showing other characteristics that would not fit being a good manager. On the other hand, if someone said “The Scots won’t vote for independence: I saw a poll showing the majority were still against it” it would be an irrelevant personal observation to say “You’ve got a criminal record, so I don’t think you can offer any acceptable view of political matters.”

A person’s character may affect their credibility (which I discussed in Critical Thinking 7), but credibility gives an argument incrementally more or less weight. It never justifies the absolute acceptance or dismissal of an argument on the grounds of character. So, to spot an ad hominem, look out for sweeping dismissals (or occasionally, sweeping acceptances) without any incremental engagement with the complex inter-relationship between character and argument.

Exercise

Are the following fallacious ad hominems, or reasonable and relevant comments on character, or somewhere in between?

1. Harriet Harman has recently been in dispute with the Daily Mail over allegations that her past involvement with the National Council for Civil Liberties, at a time when the Paedophile Information Exchange was an affiliate of NCCL, meant that she was an “apologist for paedophilia”. Harman posted a tweet, in which she included a picture from Mail Online showing three bikini-clad girls (all under 18), and asked: “When it comes to decency and sexualisation of children, would you take lessons from the Daily Mail?”

2. ‘Gentlemen of the jury, because I have justice on my side, I am sure you will not be influenced by this gentleman’s pretended knowledge of the law. Why. he doesn’t even know which side of his shirt ought to be in front!’  Abraham Lincoln

3. David Cameron was elected promising “the greenest government ever”, but the number of international flights taken by the Prime Minister with his entourage is just as high as the number taken by his predecessors.

4. The baby boomer generation, who have benefitted massively from rising property prices without lifting a finger, have no right to tell younger people that they will have to work hard for a decent living.

5. George Osborne has a 2:1 in Modern History from Oxford. That hardly equips him to be Chancellor of the Exchequer, a post that obviously requires a profound grasp of Economics.