That's the theory, anyway, although whether it's true or not remains to be seen.
This is kinda the whole point of "Goëdel, Escher, Bach", which BTW is a fantastic book and discusses in length (among other things) brain structure & operation: visual processing, memory storage, symbolic representation, etc. It should be required reading for all nerds. His basic point is that a sufficiently complex system capable of self-representation may be enough to explain consciousness and the appearance of self-determination.
My problem is that it's an unsupported conclusion: maybe it's that way, maybe it isn't, and damned if we can figure out which. I think Hofstadter buys into the idea that self-determination is an illusion (the "noisy meat robot" theory). It's been a while since I read it, and I haven't gone on to his other works, so someone correct me if I'm wrong - I wouldn't want to misstate the guy's position.
mcgrew's position is based on empirical observation: we appear to our own senses (the only way we have of perceiving the world) to be more than machines, and despite interesting theories to the contrary, this is still a reasonable position to hold. Personally, I think we are "special" in that we do truly have free will (although that may be the inevitable result of any sufficiently complex self-representing system), but we are also conditioned animals with environmentally-formed behaviors, and the number of times we truly exercise our willpower to overcome instinct may be much smaller than anyone realizes.
But again, that's my own theory.