What is an ad hominem fallacy?
An ad hominem fallacy (Latin for ‘to the person’) is considered to be a logical error where someone attacks the personal traits or motives of the person making an argument, instead of addressing the actual substance or validity of the argument itself. Often this is a diversionary tactic where the person committing the ad hominem cannot address the substantive issue at hand.
Consider the following examples:
Don’t believe that eye-witness about the car accident. Only last week I heard her lying to my neighbour that she had picked up her litter.
I wouldn’t believe that climate scientist about global warming. He receives consultancy fees from a solar panel manufacturer.
Don’t accept financial advice from that wealth manager. I saw him doing the 4D yesterday.
Note that merely attacking the person does not in itself make an ad hominem fallacious. Sometimes the character of the person is relevant to the credibility of their argument. For example:
Do not believe this eye-witness. He has previously been convicted several times for lying under oath to the court.
Strictly speaking, the past is not necessarily a guide to the future, so the fact that the eye-witness has lied in the past does not necessarily mean he is lying in the present. Indeed, he may well be telling the truth this time – think of the boy who cried wolf. However, a person’s basic honesty is usually seen as a fundamental facet of their personality, so the probability leans more to the possibility that he is lying now.
In terms of critical thinking, a good rule of thumb is to focus on the argument and evaluate it based on its merits and demerits, regardless of the arguer.
