Can you remember with your leg, and is that part of who you are? An interesting piece by Ben Platts-Mills in Psyche suggests it might be so. This is not Psyche the good old journal that went under in 2010, alas, but a promising new venture from those excellent folk at Aeon.

The piece naturally mentions Locke, who put memory at the centre of personal identity, and gives some fascinating snippets about the difficult lives of people with anterograde amnesia, the inability to form new memories. These people have obviously not lost their identities, however they may struggle. I have always been sceptical about the Lockean view more or less for this reason; if I lost my memories, would I stop being me? It doesn’t quite seem so.

In the cases mentioned we don’t quite have that total loss, though; the subjects mainly retain some or all of their existing memories, so a Lockean can simply say those retained memories are what preserve their identity. The inability to form new memories merely stops their identity going through the incremental further changes which are presumably normal (though some of these people do seem to change).

Platts-Mills wants to make the bolder claim that in fact important bits of memory and identity are stored, not in the brain, but in the context and bodies involved. Perhaps a subject does not remember anything about art, but fixed bodily habits draw them towards a studio where the tools and equipment (perhaps we could say the affordances) prompt them to create. This clearly chimes well with much that has been written about various versions of the extended or expanded mind.

I don’t think these examples make the case very strongly, though; Platts-Mills seems to underestimate the brain, in particular assuming that the absence of conscious recall means there’s no brain memory at all. In fact our brains clearly retain vast amounts of stuff we cannot get at consciously. Platts-Mills mentions a former paediatric nurse who cannot remember her career but when handed a baby, holds it correctly and asks good professional questions about it. Fine, but it would take a lot to convince me that her brain is not playing a major role there.

One of the most intriguing and poignant things in the piece is the passing remark that some sufferers from anterograde amnesia actually prefer to forget their earlier lives. That seems difficult to understand, but at any rate those people evidently don’t feel the loss of old memories threatens their existence – or do they consider themselves new people, unrelated to the previous tenant of their body?

That last thought prompts another argument against the extended view. The notion that we could be transferred to someone else’s body (or to no body at all) is universally understood and accepted, at least for the purposes of fiction (and, without meaning to be rude, religion). The idea of moving into a different body is not one of those philosophical notions that you should never start trying to explain at the end of a dinner party; it’s a common feature of SF and magic stories that no-one jibs at. That doesn’t, of course, mean transfers are actually possible, even in theory (I feel fairly sure they aren’t), but it shows at least that people at large do not regard the body as an essential part of their identity.