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Gary Williams

"Do others have the same impression? If so, why skeptical consequences are always bad?"

I get this sense as well. The standard move is to say that if your argument leads to a local skeptical but could also lead to a global skepticism, it "proves too much". The explanatory "benefit" supposedly doesn't outweigh the cost of dealing with such global skepticism, so the premise is rejected. The problem with this style of argument is that an appeal to trade-offs is subjective, because the "best" trade-off will differ depending on the values you place on theoretical values, and last I checked value judgements are subjective.

Another move is to say that if your argument has skeptical consequences it's "uninterestingly different" from standard brain-in-the-vat or Evil Genius type skepticisms that everyone seems to think have been refuted (rather than just ignored or re-framed in different theoretical terms). I think Moorean intuitions are strong here as well.


Hi Moti,

I think there are two ways of beating people with the skepticism stick. The first way is basically the way you've suggested. (Skepticism is untenable. Your view leads to skepticism. Your view is untenable.) The other is a bit different, more methodological. We might think that an aim of a certain discussion in epistemology is to explain how knowledge, justification, rationality is acquired on the assumption that it has been. Once a view is shown to lead to skepticism, it's been shown to violate a methodological assumption that's part of the discussion. At that point, people either have to try to fend off the skeptical implications or explain why we should abandon the methodological assumption that's governing the conversation.


It seems to me that you're asking the question ("Generally speaking, however, do skeptical consequences count as evidence against the philosophical claims that imply them?) at too high a level of generality, for exactly the reason you give in the sentence immediately prior to the one in which you ask the question.

If "skeptical consequences" are just consequences to the effect that we lack knowledge/rational belief concerning matters in a given domain, then whether skeptical consequences count against philosophical claims that imply them will depend on how plausible it is that we have knowledge/rational beliefs concerning the relevant domain. Philosophers of a Moorean bent will consider it obvious that we have knowledge of the external world, and at least rational inductively based beliefs, and so will (rightly, to my mind) count it as a reductio of a view that it leads to external world or inductive skepticism.

But other sorts of skeptical consequences shouldn't (I think) count against a view. E.g., some views about the epistemology of disagreement have at least moderately skeptical consequences concerning our ability to have rational beliefs about, e.g., controversial economic/political matters. I tend to find these views pretty plausible--I do think that, e.g., disagreement among knowledgable economists about the effects of various economic policies (e.g., minimum wages) ought to lead to our being much more agnostic about questions concerning those policies than we (philosophers) tend to be.


Global skepticism a sort of reductio of any purportedly sound argument. If the argument contains premises (as it presumably will), and global skepticism obtains in virtue of those premises, then the premises cannot be known to be true, and no-one has any reason to accept the argument.

This gives us a litmus test for the import of non-global or local skepticism: if the argument's premises contain claims from the domain D in which the 'local' skepticism obtains, then the reductio has bite. There will also be serious problems with utilizing premises which are not themselves in D, but which nonetheless rely on claims in D for their own justification.

In general, I think it's a bit disingenuous to simply reduce this argumentative tactic to some kind of intuition-mongering about the falsity of skepticism. If we engage in a little imaginative reflection on the ways in which various domains of knowledge support one another, we see that the truth of even a local variety of skepticism would probably have disastrous consequences for our ability to confidently assert just about anything at all.

Moti Mizrahi

Thanks for the comments, everyone.

Gary, I am no fan of appealing to intuitions, Moorean or otherwise, but I am glad to hear that I am not the only one who has this sense.

Clayton, what are the grounds for accepting this methodological assumption? Compare methodological naturalism (MN) in science. Those who advocate MN do so because they think that the supernatural is not testable, and thus not amenable to investigation using the methods of science. Is there a parallel reasoning at work in the case of methodological anti-skepticism?

Daniel, you are right, of course, that skepticism comes in many flavors. But I don’t quite see how the reductio you speak of is supposed to work. Take, for example, inductive skepticism (IS). I suppose a reductio of the sort you mention is supposed to go like this:

1. P (assumption for reductio).
2. P implies IS.
3. IS is obviously false.
4. P is false.

The crucial premise, of course, is (3). There are many philosophers—starting with Hume perhaps—who do not think that IS is obviously false. So I’m not sure what weight, if any, this reductio is supposed to carry with those philosophers.

Nick, could you please explain in more detail how any kind of local skepticism inevitably leads to global skepticism? After all, skeptical views vary not only in terms of subject matter or domain (e.g., external world, induction, etc.) but also in terms of epistemic attitude (e.g., beliefs about subject matter S are not knowledge/rational/justified, etc.).


Hi Moti,

Well, I did say "probably", so I can't explain to you why any kind of local skepticism invariably goes global. And that's a massive topic that would take a book to investigate. But the basic idea is that, say, an induction-skeptic might (even unconsciously) rely on a huge number of contingent empirical claims when they continue to believe in an external world. The constancy of objects, for example, provides powerful prima facie support for a mind-independent external world, yet, how do we cash out or confidence in "the constancy of objects" non-inductively? Surely, the facts about constancy are not a priori: they are contingent truths, matters of probabilistic fact. If we can't avoid inductive reasoning here, we'd better find some other route to the external world. Perhaps there is some such route, but we've still got a lot of work to do in order to 'contain' the skepticism.

Moti Mizrahi

Thanks for the follow-up, Nick. You’re right that this is a massive topic. I didn’t mean to put you on the spot there. But I am not quite sure what you mean when you write: “But the basic idea is that, say, an induction-skeptic might (even unconsciously) rely on a huge number of contingent empirical claims when they continue to believe in an external world.” Do you mean to say that all empirical claims are inductive, and hence external-world claims, which are also empirical claims, are inductive as well?

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