The Simulation Argument

Juan Comesana pointed me to this discussion of Nick Bostrom’s Simulation Argument at digg.com. I haven’t read through all of the comments, and I think Zeno’s paradox would prevent reading all of them in any case. But they don’t seem to have got to my reply, and I wouldn’t be a real blogger if I didn’t take this opportunity for self-promotion.

It’s been a while since I wrote it, but I think my reply holds up OK. If I was doing it now I’d make much more of the evidential internalism assumption in Bostrom’s argument. It is very intuitive at first that we have the same evidence as a BIV. I guess if it wasn’t I guess these sceptical arguments wouldn’t have the pull they actually do. But I don’t think that a purely phenomenal account of evidence actually has much to be said for it on reflection. It seems to be constitutive of the notion of evidence that evidence is a guide to the truth. So even if our evidence is constituted by our phenomenal states (which I doubt), we shouldn’t think that a BIV’s evidence is constituted by its phenomenal states, because its phenomenal states don’t give it any information about how the world is. So we don’t have the same evidence as a BIV, so nothing about its doxastic/epistemic state is relevant to our doxastic/epistemic state. And that’s even ignoring the worries about indifference that I set out (at interminable length) in that paper and in the paper on Elga’s indifference principle.

7 Replies to “The Simulation Argument”

  1. “It seems to be constitutive of the notion of evidence that evidence is a guide to the truth … [W]e shouldn’t think that a BIV’s evidence is constituted by its phenomenal states, because its phenomenal states don’t give it any information about how the world is.”

    Does this thought (or something close) mean that it is constitutive of the notion of evidence that there is no misleading evidence?

  2. No, it’s just meant to rule out all evidence being misleading. Maybe that can’t be done, but here’s how I’m conceiving of it.

    A book of baseball statistics is a guide to the facts about how various baseball players played. It might be misleading because of typos etc, but taken as a whole it is a guide to the truth about a subject matter, albeit a fallible guide. Even one of the mistaken entities is a (misleading) guide to some fact about baseball in a way that it isn’t a guide to, say, the history of the Roman Empire.

    Short version: whether something is a guide to something else depends on whether the first kind of thing is typically related to the second kind of thing in the right kind of way, while whether it is a misleading guide or not depends on whether the typical relationship holds in this particular case.

  3. Not sure I’m seeing what you’re after here. It could be that perception is typically related to the state of the external world in the right kind of way (it works fine for all us non-BIVs), just not in the BIV’s particular case.

  4. Well possibly if there are more normal people than BIVs. (I’m not sure I believe this, but I don’t have arguments against it.) But remember that the possibility I’m arguing against here is one where most things with phenomenal states like ours are BIVs. In that case phenomenal states don’t look much like evidence.

  5. It seems to be constitutive of the notion of evidence that evidence is a guide to the truth.

    That doesn’t necessarily make it constitutive of evidence that it be an accurate guide to the truth. Guides themselves can mislead.

    So far I’m making a sort of obnoxious point about the ordinary use of ‘guide’, but I think there’s a real point here. Someone might reply, “It’s constitutive of evidence that it’s the only thing we have to go on when we’re trying to figure out the truth. That doesn’t necessarily mean that it will actually help us get to the truth, alas.” I think the idea that the BIV has phenomenal evidence might be defensible from there. Not saying I believe it, just that the Bostromian could base his argument on that notion of evidence, and then it wouldn’t be so easy to overturn the evidential internalism assumption.

  6. But if evidence is everything we have to go on, then why shouldn’t all the causal influences on me count as things I have to go on? They may or may not be accurate guides to the truth of anything, but that’s not meant to be necessary for evidence. Since I have a different causal history to a BIV, I have different evidence to it.

  7. It boils down to how you count “having it to go on.” I personally really do think that something I have to go on is the fact that I’m sitting in a chair, seeing a computer screen, hearing birds outside, etc. etc. But I don’t think there’s any incoherence in thinking that evidence has to be accessible in some way, and that that accessibility means it has to be phenomenal. In much the same way as a street map sitting on the shelf in the library is still a guide to the city, but it won’t guide you to the library.

    I do think that some of the arguments for the phenomenal conception of evidence rely on a notion of incorrigibility that I don’t accept at all; I just don’t think we can force the skeptic to accept a conception of evidence that undermines skepticism.

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