The ghost and the machine

The Future of Humanity Institute, headed by transhumanist Nick Bostrom, has released a report proposing how we might get a point where we have the technology to emulate (not just simulate) an entire human brain in a computing substrate. In its introduction (which I admit is as far as I can get in the 130 pages), this "roadmap" states that whole brain emulation would make "digital immortality" possible. I assert that merely emulating someone's brain would not be enough to preserve that person entirely. I am no dualist, but I think there is more to a human mind, to a self or a soul, than just the brain. There's also the body.

We human beings are vast networks of nerves. Although it is true that by far the largest cluster is our brains, that doesn't mean all nervous activity goes on within our skulls. (I think it was in Kinds of Minds that Dan Dennett said that a mind includes much of the body, not just the brain.) Consider this: the sound of your voice is a major element of your identity, at least to the people who know you, and your vocal timbre depends on non-neurological factors like the size and shape of your vocal cords – as well as the rest of your body. All sorts of biological factors, like your metabolism and your tastebuds, form part of your mental experience and usually your identity. More dramatically, we humans have an intimate connection to the macroscopic bodies – not that we "inhabit" – but that we are. Our sense of self is predicated inextricably on our physical existence. Nick Bostrom and Anders Sandberg talk about body simulation in their report, but I say that isn't enough. For digital immortality, I posit, in addition to whole brain emulation, you need whole body emulation. There may be even more requirements for full human preservation than this. For one, a simulated environment certainly wouldn't be enough. True human existence depends on a real environment or, at the least, a flawlessly emulated one.