"Swapping memories"

In Shoemaker’s Lockean memory theory of personal identity, in the absence of fission and fusion personal identity is secured by a chain of first-personal episodic quasimemories. All memories are quasimemories, but in defining a quasimemory the condition that the remembered episode happened to the same person is dropped to avoid circularity. It is important that quasimemories must be transmitted causally by the same kind of mechanism by which memories are transmitted. If I acquire vivid apparent memories of events in Napoleon’s life by reading his diaries, these apparent memories are neither memories nor quasimemories, because diaries are not the right kind of mechanism for memory transmission, and so Shoemaker can avoid the absurd conclusion that we can resurrect Napoleon by means of his diaries. If you wrote down an event in a diary, and then forgot the event, and then learned of the event from the diary, you should not automatically say “I now remember” (of course, the diary might have jogged your memory—but that’s a different phenomenon from your learning of the event from the diary).

It seems to me that discussion of memory theory after Shoemaker have often lost sight of this point, by engaging in science-fictional examples where memories are swapped between brains without much discussion of whether moving a memory from one brain to another is the right kind of mechanism for memory transmission. Indeed, it is not clear to me that there is a principled difference between reading Napoleon’s memory off from a vivid description in his diary and scanning it from his brain. With our current brain scanning technology, the diary method is more accurate. With future brain scanning technology, the diary method may be less accurate. But the differences here seem to be ones of degree rather than principle.

If I am right, then either the memory theorist should allow the possibility of resurrecting someone by inducing apparent memories in a blank brain that match vivid descriptions in their diary (assuming for the sake of argument that there is no afterlife otherwise) or should deny that brain-scan style “memory swapping” is really a quasimemory swap and leads to a body-swap between the persons. (A memory swap that physically moves chunks of brain matter is a different matter—the memories continue to be maintained and transmitted using the usual neural processes.)