Berkeley Letters and Science Faculty Forum. January 22, 2007. I always have problems understanding what John Campbell http://www.amazon.com/exec/obidos/asin/0199243816/braddelong00 is saying. He says that he is saying:
- There is an important and unbridgeable gulf between our notions of physical causation and our notions of psychological causation.
- Martian physicists--intelligences vast, cool, and unsympathetic with no notions of human psychology or psychological causation--could not understand why, could not put their finger on physical variables and factors explaining why, the fifty or so of us assemble in the Seaborg Room Monday at lunch time during the spring semester.
He says that he is not saying any of:
- The universe has a dual nature, in which mind is different from not-mind.
- Reductionism is wrong because there are important emergent properties of complicated systems, and reductionist and holistic explanations are quantitatively different.
- There is an important and unbridgeable gulf between understanding based on physical laws and understanding based on human empathy. Instead, Campbell says, there is only one kind of understanding and explanation, but it is applied to different sets of causal factors in different circumstances.
The word "supervenience" was not mentioned by anybody.
I had two questions for him. I think I would have understood him if I could have understood the answers to either of them:
If I were a member of a team of tentacled Martian physicists (don't get me started on the image of mollusc-like Martians living on an essentially desert planet), my physical-description model of Berkeley would include a model of Assistant Dean Chuck Stroup's brain at the subatomic level. I would then be able to say: "Aha! Suppose we were to decrease the levels of serotonin in the particular half-cubic-foot of space that is Chuck Stroup's brain; then the email messages containing the string "L&S Faculty Forum today" don't get sent, and we don't assemble here for lunch. Wouldn't that be a way for Martian physicists with no concept of human psychology to begin to understand why we are all here in the Seaborg Room right now?
Let me roughly quote from a lecture from a course, Physics 140, that I took as a junior from Ed Purcell: "How about the lithium atom? We can't calculate the joint orbitals of all three electrons--that's too hard. But we can get an approximate solution for the valence electron. It wants to be in the ground state, but the Pauli Exclusion Principle forbids it. So we can model the orbital of the third, valence electron as a single electron moving in the field of the nucleus partially shielded by the other two electrons in the next stable energy level above the ground state. The Schrodinger equation is... [Purcell starts doing math.]" Here we have a mixture of physical and psychological causation. The physical causation--the math driven by the physical laws of quantum mechanics--comes at the end. Before that comes psychological causation: Purcell attributes human-like intelligence to the electron that has desires and needs and to the brooding overall universal presence that is the Pauli Exclusion Principle, and so reduces the physical-causation problem to a simpler one that is approximately right and that he can solve. The resort to psychological causation is a way to get an answer even though the math for the three-electron problem is beyond our grasp. What is the difference between Ed Purcell's use of psychological causation here and your use of psychological causation as a factor in addition to serotonin levels in understanding human psychological depression?
But alas! I did not understand his answers--although I have no doubt that he did.
I can't help but think that the rhetorical trope of "Martian physicists" is a problem here. I take it for granted that "Martian physicists" have models of human brains at a subatomic level and understand the dynamic evolution of brain states and the connection of brain states to human actions, and do so at a level that makes "psychology" needless save as a shorthand way of dividing brain states into categories. Philosophers' "Martian physicists" don't seem to be able to do that.