Not according to Keith B. Wiley and Randal A.Koene. They contrast two different approaches to mind uploading: in the slow version neurons or some other tiny component are replaced one by one with a computational equivalent; in the quick, the brain is frozen, scanned, and reproduced in a suitable computational substrate. Many people feel that the slow way is more likely to preserve personal identity across the upload, but Wiley and Koene argue that it makes no difference. Why does the neuron replacement have to be slow? Do we have to wait a day between each neuron switch? hard to see why – why not just do the switch as quickly as feasible? Putting aside practical issues (we have to do that a lot in this discussion), why not throw a single switch that replaces all the neurons in one go? Then if we accept that, how is it different from a destructive scan followed immediately by creation of the computational equivalent (which, if we like, can be exactly the same as the replacement we would have arrived at by the other method)? If we insist on a difference, argue Wiley and Koene, then somewhere along the spectrum of increasing speed there must be a place where preservation of identity switches abruptly to loss of identity; this is quite implausible and there are no reasonable arguments that suggest where this maximum speed should occur.
One argument for the difference comes from non-destructive scanning. Wiley and Koene assume that the scanning process in the rapid transfer is destructive; but if it were not, the original brain would continue on its way, and there would be two versions of the original person. Equally, once the scanning is complete there seems to be no reason why multiple new copies could not be generated. How can identity be preserved if we end up with multiple versions of the original? Wiley and Koene believe that once we venture into this area we need to expand our concept of identity to include the possibility of a single identity splitting, so for them this is not a fatal objection.
Perhaps the problem is not so much the speed in itself as the physical separation? In the fast version the copy is created some distance away from the original whereas in gradual replacement the new version occupies essentially the same space as the original – might it be this physical difference which gives rise to differing intuitions about the two methods? Wiley and Koene argue that even in the case of gradual replacement, there is a physical shift. The replacement neuron cannot occupy exactly the same space as the one it is to replace, at least not at the moment of transfer. The spatial difference may be a matter of microns rather then metres, but here again, why should that make a difference? As with speed, are going to fix on some arbitrary limit where the identity ceases to be preserved, and why should that happen?
I think Wiley and Koene don’t do full justice to the objection here. I don’t think it really rests on physical separation; it implicitly rests on continuity. Wiley and Koene dismiss the idea that a continuous stream of consciousness is required to preserve identity, but it can be defended. It rests on the idea that personal identity resides not in the data or the function in general, but a specific instance in particular. We might say that I as a person am not equivalent to SimPerson V – I am equivalent to a particular game of SimPerson V, played on a particular occasion. If I reproduce that game exactly on another occasion, it isn’t me, it’s a twin.
Now the gradual replacement scenario arguably maintains that kind of identity. The new, artificial neurons enter an ongoing live process and become part of it, whereas in the scan and create process the brain is necessarily stopped, translated into data, and then recreated. It’s neither the speed nor the physical separation that disrupts the preservation of the identity: it’s the interruption.
Can that be right though – is merely stopping someone enough to disrupt their identity? What if I were literally frozen in some icy accident, so that my brain flat-lined; and then restored and brought back to life. Are we forced to say that the person after the freezing is a twin, not the same? That doesn’t seem right. Perhaps brute physical continuity has some role to play after all; perhaps the fact that when I’m frozen and brought back it’s the same neurons that are firing helps somehow to sustain the identity of the process over the stoppage and preserve my identity?
Or perhaps Wiley and Koene are right after all?