Assessing authorities
Sometimes we decide that a premise is true not by thinking it through (as we did above with the smoking example) but by accepting it because someone else says it’s true. In some cases that’s a perfectly reasonable thing to do: in some cases it isn’t.
Joe at the bus-stop says that interest rates are about to go up. Should I believe him? Not straight away. There are two lines of questioning I could engage in. I could ask for his credentials, and if he’s a banker I might think that was reason enough to accept what he says. Or, I could ask for his evidence – what reasons does he have for thinking that interest rates are about to go up? – and then evaluate his reasons for myself.
If I am competent to evaluate his reasons, then I should probably do the second of those things (though of course sometimes there just isn’t time to do this properly). But if you’re doing the first thing – accepting what someone says because they’re an expert, without asking what their reasons are for believing what they’re saying – then you should check whether or not the following conditions apply:
- The person must be a genuine authority in the area in question.
- There must be substantial agreement between authorities.
- The authority must be testifying honestly.
If any one of these conditions is not met, the appeal to authority is fallacious.
1) The person must be an authority in the relevant area. Sportsmen endorsing sports shoes is one thing: sportsmen endorsing insurance companies is another. If an All Black tells me Nike are the best, I might reasonably (setting aside for the moment the question of how much he’s been paid to say so) think that he knows what he’s talking about: presumably All Blacks do have considerable experience with sports shoes. On the other hand, if the All Black tells me that Tower is the best insurance company, or touts the nutritional benefits of Weetbix, I should think twice. Is there any reason to think that what an All Black says about insurance is more likely to be true than what Joe at the bus-stop says about insurance? Is there any reason to think an All Black is an expert on nutrition? Probably not.
2) There must be agreement amongst experts in the area in question. If the issue is one that authorities almost all agree on, like which planet in our solar system has the greatest mass, then the appeal to authority may be legitimate. If there is no agreement even amongst the experts, then the appeal to authority is not legitimate.For example, there is no agreement amongst experts on horse-racing about who is the greatest racehorse of all time. Suppose that the ten top horse-racing experts back ten different horses. Under those conditions, if I conclude because expert Z says so that Phar Lap is the greatest racehorse of all time, I don’t really have very good reason at all to believe that conclusion.
3) If there is good reason to doubt the honesty of an expert, then appealing to what that expert says is not a legitimate appeal to authority. For example, in a trial, if you discover that the expert called by the prosecution is being paid to testify in a certain way, that discredits their testimony.
It is particularly difficult and time-consuming finding out whether or not all or most experts are in agreement. In the situation in which you’re on a jury and you’re trying to evaluate the testimony of expert witnesses, you can probably assume that if experts disagree the attorneys will tell you this. If the defence’s expert witness is the only one who believes the claim that they’re making about DNA matching, you can rely on the prosecution, if they’re halfway competent, to point this out.
In everyday life, there isn’t time to check everything. We’re bombarded with information from all sides, and while we shouldn’t believe every word of it, we can’t check the credentials of every person (or every magazine or newspaper) either. If you have a normally reliable source, you will probably be inclined to believe what they say unless it sounds, based on your own experience, highly implausible. That’s okay. Most of it doesn’t matter very much. If it does matter, you are, and should be, more careful in your checks.
