Topics Logic

Question I’m familiar with syllogistic arguments, but hardly an expert. In a recent debate about logical fallacies, I made the following points. So-called logical fallacies do not apply to inherently sound arguments (much as, for example, libel isn’t libel if the statement is true). Therefore, it is logically sound to "appeal" to numbers or to authorities IF the majority or the authority being cited: (1) has legitimate expertise on the topic (e.g., a doctor, not a mechanic on a medical matter); (2) is cited only in the area of its expertise (e.g., don't cite computer programmers on a biological question); and (3) the subject-matter experts generally agree on the statement (as, for instance, most oncologists agree that smoking is a cause of lung cancer). In other words, it is perfectly logical to accept as valid the consensus of lung-cancer researchers that smoking is a leading cause of lung cancer. I may have phrased my case ineptly, but I wonder if my argument is correct, or at least on the right track. Thank you.

Accepted:
March 4, 2007

Comments

Thanks for your question. According to the standard technical definition of a sound argument (defined as a valid argument with all true premises, and where a valid argument is defined as an argument such that there is no way for the conclusion to be false while all the premises are true), it is possible for an argument to be sound but fallacious. For instance, we would normally call a circular argument (where the conclusion appears as one of the premises) fallacious, but according to the definition of a sound argument I just gave it is obviously sound. Second, appealing to authorities as you describe in your question may be rational, justified, and the like, but it is not sound if put in the form: "The authorities claim that P, therefore P", or something slightly less trivial. Obviously, and alas, all the authories might agree on an issue, and back up their view with evidence, and still be wrong.

Now this might just show that the standard definition of a sound argument as used in logic is too impoverished. However, it turns out to be quite hard to expand the definition of a good argument to include restricted appeals to authority of the sort you adduce. Research being actively pursued now on the epistemology of testimony is concerned in part with this issue. In lieu of waiting for the results of that research, I'd suggest that certain appeals to authority might show a conclusion to be *probable*, but don't guarantee the truth of that conclusion. As long as you keep that distinction in mind, I suspect you're on solid ground in appealing to certain kinds of authority.