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Thesis The incredulous stare is a perfectly respectable argument against modal realism

Alistair Gow Contributor
· 5 replies · 180 views
Possibility & necessityAnalyticModern EuropeanDavid LewisG. E. MooreThomas Reid#common-sense#incredulous-stare#modal-realism#philosophical-method
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Where it stands

I have been reading the threads on Lewis and his infinitely many concrete worlds. I am told the standard response, the "incredulous stare", is not an argument, and that Lewis himself said so. I want to defend the stare.

In medicine we routinely reject hypotheses that would explain the symptoms beautifully but require something extraordinary. If a theory of a patient's headache requires a hidden twin, I will look elsewhere long before I have a refutation. That is not a failure of imagination; it is a sensible prior.

The Scottish common-sense philosophers made this into a method. Reid argued that when a philosophical conclusion conflicts with principles we cannot help believing, the burden falls on the philosophy. Moore did something similar with his hands. Both may be wrong in particular cases, but the general policy, "an argument whose conclusion is wildly implausible probably has a false premise somewhere", strikes me as rational.

So: an incredulous stare is a compressed argument. It says: I am more confident that there are not infinitely many talking donkeys somewhere than I am of any premise in your case. That is a real comparison of credences, and Lewis has to beat it, not dismiss it.

Convince me otherwise.

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5 replies

For the thesis 1

  1. Oskar Nyberg

    For Fellow

    I'm for the stare, with a refinement. Lewis says intuitions are the data philosophy works from and that theories are judged by how well they fit our pre-theoretical opinions. On his own method, then, a massive clash with opinion is evidence against a theory. He cannot coherently say the stare is not an argument and also that opinion is the data. What he can say is that the evidence is outweighed.

    Helpful · 2

Against the thesis 2

  1. Tomasz Wójcik

    Against Fellow

    I think you are half right, Alistair. The stare is legitimate as an expression of a prior. Where it fails is as a reason to prefer a rival theory, because every rival has its own costs. The question Lewis poses is not "is modal realism plausible?" but "is it less implausible than the alternatives, each of which needs primitive modality or unexplained abstract objects?" Your stare has to be weighed against those costs, and many people never do the weighing.

  2. Derek Hollis

    Against Fellow

    Against, mildly. History is full of stares at things that turned out true: a moving Earth, curved spacetime, people from your town being related to apes. The stare tracks how strange a claim feels, which tracks what we are used to. I'd count it as a weak argument, not a respectable one.

    Helpful · 3

Other replies

  1. Lars Eriksen

    Fellow

    Physicist's footnote, because this comes up whenever the topic does: Lewis's worlds are not the branches of Everett's many-worlds interpretation. Everettian branches are parts of one physical universe described by one wavefunction, and they arise from physics. Lewis's worlds are causally and spatiotemporally isolated, and they include worlds with entirely different laws. You can stare at both, but they are separate stares.

    Helpful · 1
  2. Alistair Gow

    Contributor

    Derek, the moving Earth is the case everyone cites, but it won by evidence. Nobody will ever see a talking donkey from another world; by construction we can't. So the stare against Lewis can only be overcome by theoretical benefit, never by observation. That makes it, I think, more respectable than the stare against Copernicus, not less.

    Tomasz's point I accept. The stare tells me Lewis has a large cost. It does not tell me the alternatives are cheaper. I will revise to: the stare is a respectable argument that has to be weighed, not a trump card.