I was gratuitously plugging my Sims paper on Crooked Timber, and I got a few comments about how I didn’t really seem to have got to the heart of the worry Bostrom raises (see here and in the comments thread on my post). At first I was inclined to agree (as in the comments thread to Matthew Yglesias’s post, but on reflection I’ve decided I should have come out swinging harder.
Fodor says somewhere that it’s a law that every technical problem has a technical solution. It looks to some like I’m just raising a technical problem for Bostrom, so it’s a law that it has a solution. If all I’ve done is given Bostrom a reason to read up on some more stats to tidy up the argument, then it’s reasonable to believe that there is a way to tidy up the argument even in advance of his expositing it. So let me try and make the argument as non-technically as possible.
Quick summary of Bostrom’s argument, without the technical details because I want to give the non-technical response. Given some plausible hypotheses about the world, most creatures with experiences kinda like yours are simulations, not material objects. So you’re probably a simulation, not a material object. (The technical objections are all to do with what goes on at the point the arguers say ‘So’. To cut a long story short, there’s an unstated premise here, and it’s inconsistent. Let’s, perhaps generously, bracket those objections.)
We can concede the premise. True, the vast majority of things with experiences kinda like mine are simulated. And what I’m kinda like is part of my evidence. But it isn’t all of it, because I know a lot more than what I’m kinda like. And we should never make judgements from a part of our evidence set when there’s potentially more evidence to use.
To pick a salient example, most things with experiences kinda like mine don’t have their emotional well-being tied to Red Sox wins and losses. No reason yet to conclude that how happy I’ll be this October is more-or-less independent of how the Red Sox do, because I know something more about my particular position in the world.
I actually know quite a lot about my position in the world, on a bit of reflection. There are particular combinations of experiences I’ve had that I can be just about certain no one else in the universe has had or will have. (If the universe is infinite I can’t be so sure, but if the universe is infinite the sense in which ‘most’ creatures like me are simulations becomes elusive. I doubt there’s a higher cardinality of simulated beings than material beings.) What’s the percentage of creatures with experiences just like mine that are simulated, and what’s the percentage that’s material? Bostrom doesn’t know. All he can say is because he doesn’t know, it shouldn’t matter, so I should use the percentages of creatures kinda like me. His motto is ignore evidence when you can’t figure out what effect it has.
What do I say? Well some days I say I do know. I know the percentage of beings with experiences just like mine that are material is 100. In that case, by Bostrom’s reasoning, I should infer I’m material. This isn’t an argument that I’m material, it’s an argument that Bostrom’s reasoning, plus what I know about myself, doesn’t undermine my confidence that I’m material. There’s no reductio argument against knowledge of your own materiality from simulation considerations.
Other days I might waver. At least for the sake of the argument I might, because really I feel I do know the relevant percentage and no one’s given me a good reason to think I don’t. But let’s pretend I’m prepared to doubt this really is knowledge. I still don’t feel any force of Bostrom’s argument. Still, there’s a big chunk of evidence I have that Bostrom says I should ignore, and I don’t know why. He says I should pay close attention to the percentage of people kinda like me that are simulations. I say what about the evidence that tells me more about my place in the universe, evidence that I use every day in reasoning about, for instance, how I’ll feel about the Red Sox. He has to say, “I don’t know how to account for that. Maybe that’s good evidence you’re human, maybe it’s further evidence you’re a simulation, maybe (although this seems implausible) it’s neutral between the two because the percentage of people just like you who are material equals the percentage of people kinda like you who are material. But when we don’t know what to do with evidence we should always take the third option, and treat it like it’s neutral evidence.”
I say that looks like one of the three options, that the evidence is neutral, is being given special status, and I want to know why. (Especially since this is the step that leads to the inconsistencies.) And here I think the simulation argument just goes quiet, because it has nothing more to say. I say (very politely giving myself the last word) that this step needs justification, and without it I’m going to mostly ignore the argument.
If I simply don’t know what effect the largest chunk of my evidence has on the probability that I’m material rather than simulated, then it looks like I simply don’t know the probability that I’m material rather than simulated. And if I don’t know that I might be well within my rights to go on acting as if it’s 1, like I believed all along. Whether that’s within my rights or obligatory depends on some hard questions about the status of epistemic conservatism, and in particular on whether epistemic radicalism is useless or positively misguided. I waver on that question too, so the number of days where I think Bostrom has given me any reason at all to worry is vanishing.
UPDATE: I just noticed that John Turri also sprung to my defence against Yglesias. I think Matthew’s post was quite useful, because it made me think about how to spell out the argument without appeal to technical details. Hence the above rant, which was fun to write at least. (And as Andrew McGonigal quite rightly points out in the comments, I pull some punches here regarding various externalisms, criticisms which again don’t rely on technical details.)