Continued from Downward Causation I.
Does the thought experiment show the possibility of downward causation? Not by a long shot. It needs to be bolstered by further considerations. At least I hope my response to the first objection (which modifies the thought experiment to involve computers playing chess or kness in a Schroedinger’s Cattish setup) removes the worry about any question-begging appeal to the libertarian position on free will. Let’s now move on to the second objection, which Aaron was quick to raise in his comment.
Objection 2. We need not resort to the different rules of chess and kness to explain the systematic difference in the movements of knight-wise arranged microparticles in chess and kness. Take one of the two computers playing chess or kness, according as the quantum object’s spin is up or down. Whichever game it is playing, it is running the game from a program that is stored in the computer, let’s say in its hard drive. In the hard drive there will be a set of microparticles arranged chess-program-wise (call this set ‘C’), and another set of microparticles arranged kness-program-wise (call this set ‘K’). It is the difference in the initial states of microparticles in C and K that accounts for the systematic difference in the movement of knight-wise arranged microparticles in chess and kness.
My Response. Notice here that the reductive physicalist is transferring the burden of explanation from the laws governing the movement of knight-wise arranged microparticles to the initial states of microparticles arranged C-wise or K-wise. Let’s dub this move initialization. Let’s see what this move amounts to in terms of Hempel’s covering law model of explanation. Let I1, I2, …, Im be statements of initial states of microparticles, let L1, L2, …, Ln be statements of microphysical laws, LC (or LK) statements of the laws of chess (or kness), and IC (or IK) statements of initial states of microparticles in C (or K). The explanandum, EC (or EK), is the rule-governed movements of knight-wise arranged microparticles in chess (or kness).
Where I propose:
(1) I1, I2, …, Im
(2) L1, L2, …, Ln, LC (or LK)
\ EC (or EK)
The reductive physicalist instead proposes the following initialization:
(1) I1, I2, …, Im, IC (or IK)
(2) L1, L2, …, Ln
\ EC (or EK)
By this maneuver, the reductive physicalist hopes to explain the movements of knight-wise arranged microparticles in chess and kness with just the laws of microphysics and the initial conditions specifying the positions, velocities, and other properties of all microparticles involved.
Let me respond to the move of initialization with a counter-move that I call legalization. Whenever we find a recurring pattern B in recurring circumstances A for non-accidental reasons, we are warranted in positing the existence of a law to this effect: for any A and any B, if A then B. If the law is not hedged by ceteris paribus clauses, it’s a law of nature. But it could also be a ceteris paribus law, and there are such laws aplenty in the special sciences, or at levels of reality higher than the fundamental level of microphysics.
Now, let a C-duplicate be an exact replica of C-wise arranged microparticles (in other words, an atom-for-atom duplicate of the microparticles arranged chess-program-wise in the hard drive of one of our computers in the thought experiment). By supervenience, this C-duplicate, having the collective base level property of being arranged chess program-wise, must thereby also have the higher level property of being a chess program. And the chess program must issue in movements governed by chess rules when it is run. These chess movements, in turn, are subvened by movements of microparticles arranged chess-piece-wise (call these ‘C-movements’).
Thus we have a recurring pattern of C-movements in recurring circumstances involving C-duplicates. Since this is a nomic regularity, we may canonize it into law (call it C-Law). The same legalizing maneuver applies to K-movements issued by K-duplicates, so that there is also K-Law. So we now have:
(1) I1, I2, …, Im
(2) L1, L2, …, Ln, C-Law (or K-Law)
\ EC (or EK)
The above argument suggests that the move of initialization fails. Recall that the reductive physicalist, in Objection 2, tried to shift the burden of explanation from Line (2) to Line (1) of the covering law explanation. What I hope to have shown in the above argument is that Objection 2 fails to the extent that it relies on initialization.
No doubt the reductive physicalist will point out that C-Law and K-Law are different from the rules of chess and kness. C-Law and K-Law are different, because they only make reference to arrangements of microparticles giving rise to movements of other microparticles. In response, though, I wonder whether these laws are not just parasitic on the rules of chess and kness. I point out also that there are an indefinite number of such laws, as many as there are conventions available or imaginable. So is it plausible to maintain that there are all these laws on the level of microphysics? Or aren’t these nomic regularities just shadows cast on the microphysical level of the conventional rules we invent, follow and impose on some higher level of reality?
The reductive physicalist may respond that C-Law and K-Law are ceteris paribus laws (e.g., they will not obtain if the set of microparticles composing into the computer in question is lacking a proper subset that composes into the CPU), and that these laws can be derived as special cases of universal laws L1, L2, …, Ln obtaining at the microphysical level. This will be the (I hope last) objection, to be discussed in the next post of the series. But before we go on to that discussion, I ask you to reflect on the following. These rules of convention, such as those of chess or kness or the traffic regulations, do not obtain as a matter of natural necessity. These rules are arbitrary and artificial, invented for our own amusement or safety. And we know them primarily because we create and enforce them, not because we have observed certain patterns of regularity to obtain (except in derivative cases). Isn’t it remarkably strange, then, to suppose that these rules can be derived as special cases of the laws of microphysics?