One thing that Doug Hofstadter mentioned in his lecture yesterday was that many conventional ideas about physicalism – strict supervenience, law-like causality between the “levels” – are likely to be plain wrong: it seems likely that higher-level systems can be remarkably insensitive to changes in their physical underpinnings. So even though it is true that minds are implemented in brains, and brains are biological structures composed of cells and molecules and atoms which obey the laws of physics, that doesn’t mean that one can (or should) look for law-like relations between mental properties and microphysical properties.¹ Of course functionalists don’t have any problem with this. The objections seem to come, on the one hand, from philosophers like David Chalmers who see this gap as a reason to toss physicalism overboard, and on the other hand from neuroscientists like Christof Koch who expect to be able to build their house of neurobiological cards all the way up to the top.
While on this subject, Hofstadter recommended a new book by the Nobel physicist Robert Laughlin, A Different Universe – reinventing physics from the bottom down. I picked up a copy this lunchtime. From the fly-leaf:
The edges of science, we’re told, lie in the first nanofraction of a second of the Universe’s existence, or else in realms so small that they can’t be glimpsed even by the most sophisticated experimental techniques. But we haven’t reached the end of science, Laughlin argues-only the end of reductionist thinking. If we consider the world of emergent properties instead, suddenly the deepest mysteries are as close as the nearest ice cube or grain of salt. And he goes farther: the most fundamental laws of physics – such as Newton’s laws of motion and quantum mechanics – are in fact emergent. They are properties of large assemblages of matter, and when their exactness is examined too closely, it vanishes into nothing.
I suspect that this book may turn out to be more provocative than rigorous, but that’s OK.
[UPDATE: I’ve now read the first 6 chapters of the book. It’s WONDERFUL!!! Thought-provoking, mind-bending, funny, profound…. I’ll post a full review in a few days.]
¹ If this sounds poorly worded, blame me – this is my interpretation, not Douglas’s exact words.