Sometimes people who seem to be your epistemic peers – that is, people as experienced, as well trained, as thoughtful, and as intelligent as you – disagree with you.
Isn’t it a bit odd that philosophers disagree? Consider Ken and I. We’re both a reasonably well-educated, fairly intelligent, pretty perceptive, not overly neurotic philosophers. Why shouldn’t we agree about everything?
We need to distinguish between apparent and real disagreements. Suppose Ken says lima beans taste good, and I say that he’s wrong, lima beans taste bad. It seems there is no real disagreement here, just differing tastes. We only have real disagreement when two people hold opinions that cannot both be true.
Exactly where to draw the line isn’t so clear. Lima beans: differing tastes, or is there a fact of the matter whether they taste good or not? One might say there are subjective facts: they taste good to Ken, but not to me. Tasting good is not a property of lima beans, but a relation between lima beans and a person, a subject; they taste good to some people, but not to others. Our ordinary way of expressing subjective facts often disguises them as objective facts: Lima beans taste good. No they don’t.
How about disagreement on aesthetic issues. Dickens is a deep an interesting author? No he’s not; he’s a nineteenth century hack. Subjective, or objective? Jane Austen is a better author than Dickens? No she’s not! Is there a fact of the matter?
How about the abortion debate. It’s sort of puzzling, because intelligent people and learned people look at the same facts and draw opposite conclusions. But maybe the conclusions aren’t really opposite. Maybe one party is really just saying, “we really really disapprove of abortions and don't like them at all,” and the other party is saying, “we don't mind them all that much.” There's no real disagreement, just different taste. Or maybe they are not really looking at the same facts. Maybe those on one side or the other are ignoring important facts, like souls, or like the slippery and conventional nature of all classifications, even attributes like being a person, or committing murder?
So knowing what is a real and what is only an apparent disagreement is itself a philosophical problem, or a bunch of them, and rich source of disagreement.
But take a case where there is no question but that we are dealing with an objective fact. Suppose Ken and I each have a clear view of a certain tree. Suppose we are both reasonably well educated about trees but not real experts. Ken says it’s a cedar, I say it’s a redwood. Should we each lower the confidence we put in our own conclusion, on the grounds that an equally good judge has come to an opposite one?
That seems reasonable, but suppose I have carefully considered the matter. The bark looks like a redwood. The needles don’t quite look like a redwood, could be a cedar. Ken did the same. Now if I take Ken’s view into account, it seem I am just taking the same evidence into account that I already did, but weakening the conclusion. What’s rational about that?
Perhaps it’s not the very same evidence. I am adding the evidence that Ken came to a different conclusion. Think of it this way. We are both fallible devices for getting at the truth. When I came to the conclusion it was a redwood tree, that was based on the results of the device nearest at hand --- my own mind. But now I can take account of the result of a different device Ken’s mind. If the devices agree, it’s like the old advice, measure twice, cut once. But if they disagree, it’s best not to cut until you’ve considered the matter further.
But, if I measure a length twice, and come up with different results, common sense suggests the true length may be somewhere in between. Measure a third time, or split the difference. But the tree is either a redwood or a cedar. The fact that Ken and I come to different conclusions is really not evidence that it’s some kind of hybrid. Unless I think Ken has consulted evidence I haven’t, or knows more about trees than I do, his conclusion really doesn’t seem to provide me with any new information at all. Well, perhaps it shows that we aren’t really peers, and one of knows more than the other? But which one?
The issues here are more complex than meet the eye. There is in fact a large and growing disagreement about how rational people should treat peer disagreement. I’ve gotten to the limits of what I know about this debate, but following tomorrow’s program, I’ll know a lot more. I think.