Evidence for a theory vs evidence of a problem

According to the mainstream metaphilosophical view, intuitions – some sort of spontaneous, non-inferential judgments that just seem true – are used as evidence in philosophy. Philosophers are supposed to come up with thought experiments that “elicit” or “trigger” intuitions, and then rely on those intuitions when they argue for and against philosophical theories. For example, David Chalmers asks us to imagine philosophical zombies to trigger the intuition that zombies are conceivable, and this intuition is then used as evidence against physicalism (which implies zombies aren’t conceivable). Edmund Gettier tells us a story about a guy called Smith applying for a job, which triggers the intuition that Smith doesn’t know who will get the job, and this intuition is then used as evidence against the justified-true-belief theory of knowledge. Judith Jarvis Thomson tells a story about a famous violinist with a fatal kidney ailment, which triggers the intuition that it’s ok to unplug the violinist, and this intuition is then used as evidence for the claim that abortion is morally permissible even if fetuses are persons. And so on. Some call it “our standard justificatory procedure”.

Most metaphilosophers believe it, I think most philosophers in general might believe it, I certainly used to believe it myself for a long time, actually I just assumed it was the most obvious thing about what philosophers do, but then I’ve become sceptical. What interrupted my dogmatic slumber was the recent work of dissidents like Herman Cappelen, Max Deutsch, Timothy Williamson, Bernard Molyneux and Jonathan Ichikawa, who argue the methodological picture outlined above is deeply confused. According to them the intuitiveness of propositions plays no role whatsoever as far as philosophical evidence is concerned.

In response to the dissidents’ arguments, proponents of the mainstream view typically qualify it, saying it’s only about intuitions in some specific sense. Another kind of response is that there are entirely different ways of using intuitions as evidence in philosophy that are not addressed by Cappelen and others. Kevin Tobia goes for the latter approach:

It is worth noting that Cappelen restricts Centrality [Cappelen’s term for the view that philosophers rely on intuitions as evidence – TH] to the claim that philosophers rely on intuitions as evidence for philosophical theories. There are other plausible uses of intuitions in philosophy that fall outside the purview of Centrality as stated. One example is that of discovery. Rather than providing evidence for (or against) some philosophical theory, intuitions might be used as an instrument of discovery of a philosophical problem.

Take for example a Sorites argument. Williamson presents the following argument:

Consider the following argument, with premises above the line and conclusion below:

1 is a few

If 1 is a few then 2 is a few

If 2 are a few then 3 are a few

If 9,999 are a few then 10,000 are a few


10,000 are a few (Williamson 1994, 22)

Williamson continues, “The premise ‘1 is a few’ is apparently true and the conclusion ‘10,000 are a few’ apparently false. The gradualness of the sorites series makes each of the conditional premises appear true” (1994, 22–23). Williamson’s appeals that each of the premises is true and that the conclusion is false might reasonably be described as intuitions. There is no explicit appeal to a theory that is made true or falsified here, yet the argument still seems philosophically important. In this case, the intuitions are used as evidence not of a theory but of discovery of a philosophical problem.

According to Tobia, as I understand him, Williamson confronts a bunch of intuitions: “1 is a few”, “10,000 are not a few”, “Adding 1 doesn’t make a difference between a few and not a few”. He then shows they cannot all be true at the same time (at least not unless you reject standard logic, but rejecting standard logic requires giving up principles that can be described as intuitive too). So the fact that our intuitions clash is meant to be evidence of the fact that there is a philosophical problem to be solved.

I don’t think Tobia is right about this. To see why, consider situations when we come across an inconsistent set of intuitions, but it doesn’t mean that we’re dealing with a philosophical problem. This happens whenever it’s fairly clear why at least some of those intuitions are false, hence there’s little to philosophise about.

Take another famous puzzle, the Monty Hall problem. Here’s a summary by Bruce Russell:

Monty Hall was the host of the game show “Let’s Make a Deal”. Contestants would choose one of three doors and behind one of them was a big prize; behind the others, some worthless joke prize (say, a hundred boxes of tissue to dry their tears). Monty would open one of the doors with a joke prize behind it and then ask the contestant whether he wanted to stick with the door he had chosen or switch to the other unopened door. It can be shown that the probability that the contestant will win the big prize if he switches is 2/3, but only 1/3 if he sticks. But it seems to many that the probability of his winning is 1/2 regardless of whether he sticks or switches since there are only two unopened doors left.

Call the judgment that the probability of winning is 1/2 the MH intuition. We can say it clashes with other intuitions we might have about this case, like for example the (correct) intuition that initially the probability of winning is 1/3, no matter which door you choose. Or another (also correct) intuition that Monty knows where the big prize is, but the contestant doesn’t. However in this case it’s clear that the MH intuition is incorrect, and it’s clear why. A little mathematical reasoning does the job. This makes the problem not terribly philosophical. Sure, it might have some interesting philosophical implications, but you cannot have a serious philosophical debate over whether the MH intuition is correct or not, the way you can have a philosophical debate over the correctness of any of the Sorites intuitions.

So both the Sorites case and the Monty Hall case can be characterised as a conflict between intuitions, but the former is a philosophical problem while the latter is not. Why is that? It’s because intuitions don’t indicate we’re on to something philosophical. What makes the Sorites philosophical is the fact that there is a conflict not between intuitions, but between claims we believe to be true, and it’s unclear to us how any of them can be falsified. We find out they cannot all be true at the same time, but it’s hard to tell which we should give up and why. This is not the case with the Monty Hall scenario.

I guess at this point Tobia could still say: “Ok, maybe intuitions aren’t great evidence of philosophical problems. But it is still the case that Williamson relies on intuitions as evidence of a problem. After all, he uses expressions like “apparently true”, or “appear true” – these must refer to intuitions. Maybe in his case what is intuitive simply happens to overlap with what is good evidence, and that’s why he’s successful.”

A proper response would require some deeper exegesis of Williamson’s work, but I’m not too optimistic about this hypothesis. In my experience, charitable reading of philosophical texts usually reveals that intuitions are poor evidence of anything philosophically important, and they are treated accordingly.

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