Introduction to Ad Hominem Fallacies One of the most common non-rational appeals is an argumentum ad hominem--or, as the Latin phrase suggests, an "argument against the person" (and not against the ideas he or she is presenting). Our decisions should be based on a rational evaluation of the arguments with which we are presented, not on an emotional reaction to the person or persons making that argument. But because we often react more strongly to personalities than to the sometimes abstract and complex arguments they are making, ad hominem appeals are often very effective with someone who is not thinking critically. Consider a few examples: A political candidate is gaining support by proposing a tax change. So her opponent argues that the candidate herself would be one of the chief beneficiaries of that tax change. Your doctor tells you to lose some weight. But why should you listen to a doctor who is himself overweight? A friend has recommended a new investment opportunity, but your significant other rejects the recommendation with the remark, "How could you possibly value the advice of that idiot?" In each of these cases, there is an argument (concerning taxes, health, or investments); and in each, the argument is given less importance than something about the person making that argument. And that's what is wrong with ad hominem appeals. After all, if the tax proposal is an improvement, if the medical diagnosis is sound, if the investment opportunity is worthwhile--then what difference does it make who is presenting the argument--or even why? Ad hominem fallacies take a number of different forms, though all share the fact that they attempt to re-focus attention, away from the argument made and onto the person making it. And remember--it doesn't really matter whether the terms of the attack are true or false. What matters is whether the argument is acceptable, not the person arguing it. After all, even if Adolf Hitler says so, 2 + 2 still equals 4. Among the most frequent ad hominem appeals are attacks on: personality, traits, or identity: "Are you going to agree with what that racist pig is saying?" "Of course she's in favor of affirmative action. What do you expect from a black woman?" affiliation, profession, or situation: "What's the point of asking students whether they support raising tuition? They're always against any increase." "Oh yeah, prison reform sounds great--until you realize that the man proposing it is himself an ex-con." inconsistent actions, statements, or beliefs: "How can you follow a doctor's advice if she doesn't follow it herself?" "Sure, he says that today, but yesterday he said just the opposite." source or association for ideas or support: "Don't vote for that new initiative--it was written by the insurance lobby!" "You can't possibly accept the findings of that study on smoking--it was paid for by the tobacco industry." The point is that each argument must be evaluated in its own right. Information or suspicions about vested interests, hidden agendas, predilections, or prejudices should, at most, make you more vigilant in your scrutiny of that argument--but they should not be allowed to influence its evaluation. Only in the case of opinions, expert and otherwise, where you must rely not on the argument or evidence being presented but on the judgment of someone else, may personal or background information be used to evaluate the ideas expressed. If, for example, a used car vendor tries to prove to you that the car in question is being offered at lower than the average or "blue book" price, you must ignore the fact that the vendor will profit from the sale, and evaluate the proof. If, on the other hand, that used car vendor says, "Trust me, this is a good deal," without further proofs or arguments, you are entitled to take into account the profit motive, the shady reputation of the profession, and anything else you deem to be relevant as a condition of "trust."