Quoth The Philosopher:
A well-educated man will expect exactness in every class of subjects, according as the nature of the thing admits. (Nicomachean Ethics)
In short: the subject matter determines the degree of certitude we may have about our conclusions concerning it. There’s the certainty of the syllogism, which must be true if the premises are true or valid and the conclusion follows from them; but on the other hand there are things we can only be much less certain about too. A good example is the weather: not even the experts are or can be as certain as a syllogism, and although what he meant by meteorology isn’t exactly what we mean by it (for one thing we don’t include earthquakes in this subject…) he nevertheless knew and conceded at the beginning of his book De Meteora that demonstrative certainty was impossible, and that the best certitude we may hope for in the matter is that our conclusions are consistent with the facts as we see them. Aquinas understood our limitations too, as I have pointed out not too long ago.
I think that we may apply another adjective to the well-educated man: he is humble. He realizes his limitations and does not pretend to a certainty that he cannot really have. It’s perfectly okay to have mere opinions, and it isn’t an error to appeal to authority. The real trick is to know just exactly what we think we know is something we really do know: to be able to distinguish knowledge (which for Aristotle and Aquinas is something about which we have certainty and genuine cause for it) from opinion and wild-eyed guesses. When we think about it this way, what we really know turns out to be surprisingly little, on average (at least for me!), and we tend to hold a lot more mere opinions than we usually think. Opinions aren’t a bad thing at all–unless we invest them with pretensions of certainty that are unwarranted. Hence the humility that is essential to the well-educated man.
J. Mortimer Adler once offered us criteria for disagreement that I think are excellent (and at least vaguely on-topic). If I am going to disagree with a man, I have to do at least one of the following:
- Show that he is uninformed
- Show that he is misinformed
- Show that he has been illogical (his conclusions do not follow from his premises, or his premise(s) are false)
- Show that his account of things is incomplete (he hasn’t told the whole story)
If we cannot do at least one of these things, then I am obliged to agree with the man because what he has said must be true. Now, it may be the case that I lack the time, interest, talent, or other resources that are necessary in order to disprove his thesis, and so it is not necessarily dishonest to withhold assent in every case. But if I can’t show that he is wrong, it is both uncharitable and a mistake to insist that he is nevertheless in error. Once again we see the need for humility. Intellectual modesty is a good thing.