An Evolutionary Argument against Physicalism : or some advice to Jaegwon Kim and Alvin Plantinga
According to the dominant tradition in Christianity and many other religions, human beings are both knowers and actors: beings with conscious beliefs about the world who sometimes act intentionally guided by these beliefs. According to philosopher of mind Robert Cummins the “received view” among philosophers of mind is epiphenomenalism, according to which mental causation does not exist: neural events are the underlying causes of both behavior and belief which explains the correlation (not causation) between belief and behavior. Beliefs do not, in virtue of their semantic content, enter the causal chain leading to action, beliefs are always the endpoint of a causal chain. If that is true the theological anthropology of many religious traditions is false.
JP Moreland draws attention to two different ways of doing metaphysics: serious metaphysics and shopping-list metaphysics. The difference is that the former involves not only the attempt to describe the phenomena one encounter, it also involves the attempt of locating them, that is explaining how the phenomena is possible and came to be given the constraints of a certain worldview. For a physicalist these constraints include the atomic theory of matter and the theories of physical, chemical and biological evolution.
Mental properties are challenging phenomena to locate within a physicalist worldview, and some physicalists involved in “serious metaphysics” have therefore eliminated them from their worldview. Most however accept them, advocating “non-reductive physicalism” according to which mental properties supervene on physical processes. Even if one allow mental properties to supervene on physical processes, the problem of mental causation remains. If mental properties are irreducible to and therefore distinct from physical properties, as the non-reductive physicalists claim, they cannot exert causal powers if one accepts the causal closure of the physical domain – which one must, if one is a “serious physicalist” according to physicalist philosopher of mind Jaegwon Kim.
Alvin Plantinga, in his Evolutionary Argument against Naturalism, shows that if mental properties, such as the propositional content of beliefs, are causally inefficacious, then evolution has not been selecting cognitive faculties that are reliable, in the sense of being conducive to true beliefs. If the content of our beliefs does not affect our behavior, the content of our belief is irrelevant from an evolutionary standpoint, and so the content-producing part of our cognitive faculties are irrelevant from an evolutionary standpoint. The “reliability” – truth-conduciveness – of our cognitive faculties can therefore not be explained by evolution, and therefore not located within the physicalist worldview. The only way in which the reliability of our cognitive faculties can be located is if propositional content is relevant for behavior.
If we however eliminate or deny the reliability of our cognitive faculties, then we have abandoned any chance of making a rational case for our position, as that would presuppose the reliability that we are denying.
But if propositional content is causally efficacious, then that either – if we are non-reductive physicalists and mental properties are taken to be irreducible to physical properties – implies that the causal closure of the physical domain is false or - if we are reductive physicalists and not eliminativists regarding mental properties - it shows that matter qua matter can govern itself by rational argumentation, in which we have a pan-/localpsychistic view of matter. Either way, we have essentially abandoned physicalism in the process of locating the reliability of our cognitive faculties within a physicalist worldview. We have also affirmed the theological anthropology of Christianity, in so far as the capacity for knowledge and rational action is concerned.
Keywords: Philosophy of mind, mental causation, reductionism, physicalism, the evolutionary argument against naturalism, the myth of nonreductive materialism, Alvin Plantinga, Jaegwon Kim
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