Mental Causation
I’ve been reading around Non-Reductive Physicalism and Supervenient in relation to mental causation recently, having came across (or well, being forced to stumble across consider the man’s notoriety) Kim’s Causal Exclusion Argument. Below I give an outline of Kim’s argument which endorses a claim for epiphenomenalism or reductionism (Kim favours the latter in most papers I have read, as opposed to Baker who seems to adhere to the former more favourably). I then give a summary of one of the arguments against Exclusion by Corry, who gives an example of nomological co-existent sufficient causes for one event existing in fundamental physics. How Corry thought up some of the brilliant ideas in his paper is somewhat beyond me — excess mental phenomena, perhaps.
Non-Reductive Physicalism is based on three general premises. Firstly, supervenience: that higher-level properties supervene on lower level properties; without B (base) there would be no A (high-level property). So the higher-level property can be said to be fixed by the physical base (fundamental physics or something akin). Secondly, Irreducibility higher-level properties are irreducible to supervenient-base lower properties, having their own novel properties. Thirdly, higher-level properties have causal efficacy, they can instantiate a change in another property. With regards to mental phenomena, the argument in support of the claim of NRP is as follows (draw a figure). Firstly, however, I use Kim’s, Fodor’s and Corry’s usage of ‘nomological sufficiency’ in order to describe the relations between lower and higher level properties, as well as use nomological sufficiency to describe causation (this shall be elaborated on later — but it is consistent with an interoperation of Kim’s ‘thicker notion’ of causation which he leaves somewhat ambiguous). Nomological sufficiency means that, with the fundamental laws of nature being as they are, it would be impossible to have supervenient-base level property B and not have higher property A.
If mental phenomena (M) supervenes on physical base (P), then P is nomologically sufficient for M. M causes property P* (a physical state). M is therefore nomologically sufficient for P*. But if M is nomologically sufficient for P*, and M supervenes on P, this means that P is also nomologically sufficient for M, and if causation is nomological sufficiency, then P also causes P*. Kim argues that we have an issue here. First, there cannot be a causal chain from P—>M—>P*, as M has a nomological supervenient relation with P, not a causative one. Thus, this means we have two sufficient explanations for the cause of P* (as M & P are both sufficient conditions on their own for causing P*). Hence, M & P are two independent sufficient causes of P*. But this would violate Exclusion which is essentially that, if there are two independent and nomologically sufficient causes, then they cannot co-exist — one must be excluded — otherwise it is a case of overdetermination, which Kim considers absurd, since conceivably not every single mental to physical event could be a case of overdetermination. Since Kim’s Closure states that the universe is physically closed (everything is physical) and that every independent physical event has one independent sufficient physical cause then M appears to be superfluous in an explanation of causation. Rather than appealing to epiphenomenalism, Kim argues that we should reject M and see it as either impotent or required to be reduced down to P. This is the Causal Exclusion Argument.
I will argue against Kim’s Exclusion, specifically, showing how two nomologically sufficient causes need not exclude oneanother through Corry’s critique. This will then lead to an objection which I shall argue founders the Causal Exclusion Argument as a whole, as the independency of the relationship between M and P is questioned: there is empirical evidence of two nomologically sufficient properties co-existing as sufficient causes for instantiating a third property. Corry notes that there is evidence at the very fundamental levels of the coexistence of two nomologically sufficient properties being the cause of an event. In the Stern-Gerlach experiment, the spin of particles is measured. So, for electrons, protons and other particles of that ‘class’, they have a spin 1/2. When a beam of these particles is fired into an unhomogenous magnetic field, the beam can go one of two ways: the beam splits in two. Therefore it is nomologically sufficient for a particle with property spin 1/2 for a beam of this property to be split in two. However, electrons and positrons are the only particles with a resting mass of 0.511MeV. They also have a spin 1/2. Therefore it is nomologically sufficient that a particle with 0.511MeV to split a beam in two. We have a case, then, where there are two nomologically sufficient properties to instantiate the beam being split in two, in violation of Exclusion, where two or more nomologically sufficient independent properties cannot co-exist as a sufficient cause. One could argue, however, that as a particle of rest mass 0.511MeV is nomologically sufficient for a spin 1/2, these two properties are not actually independent, and are therefore immune to the Exclusion principle. However, Corry argues, with some sense of the Admiral Akbar to it, that this is his trap. If two nomologically sufficient properties are immune to Kim’s Exclusion, then higher-level and supervenient-base-level properties are also immune to the Exclusion principle, as they also have a nomologically-sufficient relation to one another. P is nomologically sufficient for the supervening mental property M. I make no claim to refute Kim’s entire critique in an hour long essay on a man who appears to have published more articles than the Mail on immigration, but the issue raised with Exclusion appears to be irreconcilable with nomological sufficiency, and as shown by Wake, Corry, Block and others, a counterfactual dependency does not seem to hold, either.
Corry, Richard. “Emerging from the causal drain”. Philosophical Studies 165 (1):29-47. Web. 19th May 2015.
Kim, Jaegwon. “Mechanism, purpose, and explanatory exclusion”. Philosophical Perspectives 3:77-108. Web. 19th May 2015.
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