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[The following is tentative material for my presentation at the Society for Philosophy & Technology Conference this summer.]
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Do Posthumanists Dream of Pixilated Sheep?
Bostrom and Sandberg's Brain Emulation,
Examined and Critiqued
Section 2:
Out, Wild Jelly!
Encoding All the
In brain emulation, we scan a particular brain to obtain precise detail of its structures and their interactions. Using this data, we program a simulation that will behave essentially the same as the original brain. Now imagine we perfectly simulate ants. Then we put thousands together. They will form a swarm with a mind of its own. Brain emulation presupposes this principle. The simulation will mimic the human brain’s functioning on the cellular level. Higher-and-higher organizations should spontaneously arise. Then finally consciousness may emerge at the highest level.
Early in this technology's development, we should only expect simpler brain states, like wakefulness and sleep. But in its ultimate form, whole brain emulation will enable us to make back-up copies of our minds. Then we might survive our body’s death.
I use the terms emulation and simulation interchangeably. But Bostrom & Sandberg draw a distinction that indicates an important success criteria. Both simulations and emulations model the original's relevant properties. The simulation reproduces only some of them. But the emulation replicates all. So it is a 1-to-1 modeling of the brain’s functioning.
Putnam calls this a functional isomorphism. It is “a correspondence between the states of one and the states of the other that preserves functional relations.” Brain and emulation are black boxes. We feed both of them the same sequence of stimuli. If they respond with the same sequence of behaviors, then they are functionally isomorphic. Hence the same mind can be realized in two physically different systems. Putnam writes, "a computer made of electrical components can be isomorphic to one made of cogs and wheels or to human clerks using paper and pencil.” Their insides may differ drastically, but their outward behaviors must be identical. If seeing blood shocks the brain, it should induce something equivalent in the simulation.
There are various levels of emulation success. The highest ones are the most philosophically interesting.
When the technology achieves individual brain emulation, it
produces emergent activity characteristic of that of one particular (fully functioning) brain. It is more similar to the activity of the original brain than any other brain. (Bostrom & Sandberg 11, emphasis mine)
A personal identity emulation is “a continuation of the original mind; either as numerically the same person, or as a surviving continuer thereof.” We achieve such a simulation when it becomes rationally self-concerned for the brain it emulates. (11)
Putnam, Hilary. “Philosophy and Our Mental Life.” Mind, Language, and Reality.
Sandberg, A. & Bostrom, N. (2008): Whole Brain Emulation: A Roadmap, Technical Report #2008‐3, Future of Humanity Institute,
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