Parfit and Vesey’s Dialogue

Photo by John Noonan on Unsplash

If Brown’s brain is divided in half and put into two other people’s brainless heads, the identity of Brown then becomes split in half as well. Although Brown’s identity did not disappear completely, his memories are now encoded into two different bodies since the brain was split into two, so he has to be either both or neither of the people. If the brain were to be put back together, Brown would be one person again, but through the split-brain thought-experiment, Brown’s identity is also split into two, so Brown himself is technically neither of the people but half of each new body. I believe that the possibility of Brown maintaining neither of the two identities — although implausible and impossible — is the most logic of the three possibilities because a part of him now resides in both of the new bodies, so his whole self was destroyed and dispersed into two new bodies. Both people can describe events in Brown’s life, so they each have a “memory belief,” the events “actually did happen,” and the “belief and memory are the same,” meaning the memory is justified and real. Because the psychological continuity lines up with both people, I believe the identity of Brown is half in one person and half in the other, resulting in neither people being Brown. He is merely a part of both people.

Arguing against the claim that Brown could be neither people, Parfit says that “relation to each of those two…