If I live long enough, I’m planning to write a book entitled “The 100 Stupidest Things Anyone Ever Said About Minds, Brains, Consciousness, and Computers”. Indeed, I’ve been collecting items for this book for some time. Here’s my latest addition: Michael S. Gazzaniga, a famous cognitive neuroscientist who should know better, writes:
Perhaps the most surprising discovery for me is that I now think we humans will never build a machine that mimics our personal consciousness. Inanimate silicon-based machines work one way, and living carbon-based systems work another. One works with a deterministic set of instructions, and the other through symbols that inherently carry some degree of uncertainty.
If you accept that the brain functions computationally (and I think the evidence for it is very strong) then this is, of course, utter nonsense. It was the great insight of Alan Turing that computing does notdepend in any significant way on the underlying substrate where the computing is being done. Whether the computer is silicon-based or carbon-based is totally irrelevant. This is the kind of thing that is taught in any third-year university course on the theory of computation.
The claim is wrong in other ways. It is not the case that “silicon-based machines” must work with a “deterministic set of instructions”. Some computers today have access to (at least in our current physical understanding) a source of truly random numbers, in the form of radioactive decay. Furthermore, even the most well-engineered computing machines sometimes make mistakes. Soft errors can be caused, for example, by cosmic rays or radioactive decay.
Furthermore, Dr. Gazzaniga doesn’t seem to recognize that if “some degree of uncertainty” is useful, this is something we can simulate with a program!