On the doppelganger issue, my intuition is to say that in realistic cases, the doppelgänger’s algorithm would have to be structured as DopplegangerAlgorithm(x) = DoTheOpposite(MyAlgorithm(x)). I.e., we do have a “shared will” in a sense, but the doppleganger is structured so as to do the opposite of what our shared will chooses.
I'm not entirely sure! I think if you or I were to try and build a doppelgänger, then probably, and this becomes more likely the more sophisticated the doppelgänger is. But for others, I don't know. If you have a physical computer that only does addition, and is optimized for that, and a physical computer that only does subtraction and is optimized for that, what is the relationship between the machines? Subtraction *can* be computed as the inverse of addition, and necessarily *is* an inverse to addition. But when we're talking about physical things like calculators, control over the adder doesn't necessarily mean control over the subtractor. I have to think about this more, though—I think the critiques of what it means for a physical system to compute a function were the best part of Will MacAskill's critique of FDT. But compatibilism might really need an answer!
Nice post!
On the doppelganger issue, my intuition is to say that in realistic cases, the doppelgänger’s algorithm would have to be structured as DopplegangerAlgorithm(x) = DoTheOpposite(MyAlgorithm(x)). I.e., we do have a “shared will” in a sense, but the doppleganger is structured so as to do the opposite of what our shared will chooses.
I'm not entirely sure! I think if you or I were to try and build a doppelgänger, then probably, and this becomes more likely the more sophisticated the doppelgänger is. But for others, I don't know. If you have a physical computer that only does addition, and is optimized for that, and a physical computer that only does subtraction and is optimized for that, what is the relationship between the machines? Subtraction *can* be computed as the inverse of addition, and necessarily *is* an inverse to addition. But when we're talking about physical things like calculators, control over the adder doesn't necessarily mean control over the subtractor. I have to think about this more, though—I think the critiques of what it means for a physical system to compute a function were the best part of Will MacAskill's critique of FDT. But compatibilism might really need an answer!