Thanks, everyone, for your comments on my paper. It’s great to see that it is generating discussion. I think I ought to take this opportunity to give a brief explanation of the argument I make in the paper, for the benefit of those who haven’t read it.
The basic argument goes like this. In the first section, I point out that the ‘Simulation Argument’ invokes (at different stages) two assumptions that I call Good Evidence (GE) and Impoverished Evidence (IE). GE is the assumption that I possess good evidence regarding the true physical limits of computation. IE is the assumption that my current evidence does not support any empirical claims non-neutral with respect to the hypothesis (SIM) that I am simulated—for example, the empirical claim that I possess two physically real human hands.
Although GE and IE may look in tension with one another, they are not necessarily incompatible. We can generate a genuine incompatibility, however, by introducing a third claim, Parity of Evidence (PE), stating that my epistemic access to the facts about my own physical constitution is at least as good as my epistemic access to the facts about the true physical limits of computation. Since GE, IE and PE are jointly incompatible, at least one of them must be false.
My own view (and a common view, I imagine) is that IE is false, while GE and PE are true. But rejecting IE would fatally compromise the Simulation Argument. So I spend most of the paper considering the two alternatives open to Bostrom: i.e., rejecting GE or rejecting PE. I argue that, if Bostrom rejects GE, the Simulation Argument still fails. I then argue that, if he rejects PE, the Simulation Argument succeeds, but it’s pretty hard to see how PE could be false. So neither of these alternatives is particularly promising.
One common response I’ve encountered focusses on GE, and asks: why does Bostrom actually need GE? Surely all he really needs is the conditional assumption that, if my evidence is veridical, then GE is true. This conditional assumption allows him to say that, if my evidence is veridical, then the Simulation Argument goes through in its original form; whereas if my evidence is not veridical because I’m simulated, then I’m simulated—so we just end up at the same conclusion by a different route.
This is roughly the line of response pressed here by Benja and Eliezer Yudkowsky. It’s a very reasonable response to my argument, but I don’t think it works. The quick explanation is that it’s just not true that, conditional on my evidence being veridical, the Simulation Argument goes through in its original form. This is essentially because conditionalizing on my evidence being veridical makes SIM a lot less likely than it otherwise would be, and this vitiates the indifference-based reasoning on which the Simulation Argument is based. But Benja is right to press me on the formal details here, so I’ll reply to his objection in a separate comment.
It seems as if your argument rests on the assertion that my access to facts about my physical condition is at least as good as my access to facts about the limitations of computation/simulation. You say the ‘physical limitations’, but I’m not sure why ‘physical’ in my universe is particularly relevant—what we care about is whether it’s reasonable for there to be many simulations of someone like me over time or not.
I don’t think this assertion is correct. I can make a statement about the limits of computation / simulation—i.e. that there is at least enough simulation power in the universe to simulate me and everything I am aware of, that is true whether I am in a simulation or in a top level universe, or even whether I believe in matter and physics at all.
I believe that this assertion, that the top level universe contains at least enough simulation power to simulate someone like myself and everything of which they are aware is something that I have better evidence for than the assertion that I have physical hands.
Have I misunderstood the argument, or do you disagree that I have better evidence for a minimum bound to simulation power than for any specific physical attribute?
Thanks, everyone, for your comments on my paper. It’s great to see that it is generating discussion. I think I ought to take this opportunity to give a brief explanation of the argument I make in the paper, for the benefit of those who haven’t read it.
The basic argument goes like this. In the first section, I point out that the ‘Simulation Argument’ invokes (at different stages) two assumptions that I call Good Evidence (GE) and Impoverished Evidence (IE). GE is the assumption that I possess good evidence regarding the true physical limits of computation. IE is the assumption that my current evidence does not support any empirical claims non-neutral with respect to the hypothesis (SIM) that I am simulated—for example, the empirical claim that I possess two physically real human hands.
Although GE and IE may look in tension with one another, they are not necessarily incompatible. We can generate a genuine incompatibility, however, by introducing a third claim, Parity of Evidence (PE), stating that my epistemic access to the facts about my own physical constitution is at least as good as my epistemic access to the facts about the true physical limits of computation. Since GE, IE and PE are jointly incompatible, at least one of them must be false.
My own view (and a common view, I imagine) is that IE is false, while GE and PE are true. But rejecting IE would fatally compromise the Simulation Argument. So I spend most of the paper considering the two alternatives open to Bostrom: i.e., rejecting GE or rejecting PE. I argue that, if Bostrom rejects GE, the Simulation Argument still fails. I then argue that, if he rejects PE, the Simulation Argument succeeds, but it’s pretty hard to see how PE could be false. So neither of these alternatives is particularly promising.
One common response I’ve encountered focusses on GE, and asks: why does Bostrom actually need GE? Surely all he really needs is the conditional assumption that, if my evidence is veridical, then GE is true. This conditional assumption allows him to say that, if my evidence is veridical, then the Simulation Argument goes through in its original form; whereas if my evidence is not veridical because I’m simulated, then I’m simulated—so we just end up at the same conclusion by a different route.
This is roughly the line of response pressed here by Benja and Eliezer Yudkowsky. It’s a very reasonable response to my argument, but I don’t think it works. The quick explanation is that it’s just not true that, conditional on my evidence being veridical, the Simulation Argument goes through in its original form. This is essentially because conditionalizing on my evidence being veridical makes SIM a lot less likely than it otherwise would be, and this vitiates the indifference-based reasoning on which the Simulation Argument is based. But Benja is right to press me on the formal details here, so I’ll reply to his objection in a separate comment.
It seems as if your argument rests on the assertion that my access to facts about my physical condition is at least as good as my access to facts about the limitations of computation/simulation. You say the ‘physical limitations’, but I’m not sure why ‘physical’ in my universe is particularly relevant—what we care about is whether it’s reasonable for there to be many simulations of someone like me over time or not.
I don’t think this assertion is correct. I can make a statement about the limits of computation / simulation—i.e. that there is at least enough simulation power in the universe to simulate me and everything I am aware of, that is true whether I am in a simulation or in a top level universe, or even whether I believe in matter and physics at all.
I believe that this assertion, that the top level universe contains at least enough simulation power to simulate someone like myself and everything of which they are aware is something that I have better evidence for than the assertion that I have physical hands.
Have I misunderstood the argument, or do you disagree that I have better evidence for a minimum bound to simulation power than for any specific physical attribute?