Doctor of Philosophy (PhD)
Faculty of Science
The problem of mental causation, at least in one of its most basic forms, is how to reconcile two plausible but potentially incompatible intuitions. The first intuition is that the mind makes a difference in the world. For example, I am writing this paragraph for certain reasons, and before long I will stop to eat something because of certain desires for food. Seemingly, these reasons and desires play a role in what happens. The second intuition is that the physical world is causally complete, so everything that happens is the result of the movement of physical particles. For example, the neural turbulence in my head seems to be the actual cause of my hands fluttering across the keyboard in certain ways, whilst certain muscle contractions in my arms cause the food to enter my mouth. What room is there for the mind to play a causal role when everything seems to happen because of the movement of physical particles?
For some time reductive physicalism was the prevailing solution to the problem of mental causation (Place, 1956; Feigl, 1958; Smart, 1959). Reductive physicalism posits a reductive identity of the mental to the physical. In so doing, it endorses physical causal completeness, but achieves mental causation as well, since the mental is identical with the causally efficacious physical. In the nineteen seventies, nonreductive physicalism replaced reductive physicalism as the predominant solution to the problem of mental causation in the nineteen seventies. Nonreductive physicalism solves the problem of mental causation by agreeing that the physical is causally complete, but achieves mental causation as well by supposing that the mental supervenes upon the physical, and thus inherits the causal power of the physical.
In recent years this nonreductive consensus has been threatened. This is partially due to an argument that has been distilled from Jaegwon Kim’s principle of causal/explanatory exclusion. One part of this compound principle is the principle of causal exclusion, which states that there can be no more than a single sufficient cause for any given event (Kim, 2005, p. 42). This principle of causal exclusion creates the following problem: the nonreductive physicalist endorses the causal completeness of the physical, and so she agrees that there is a sufficient physical cause for any given event. The nonreductive physicalist also avoids making a reductive identity between the mental and the physical, so she agrees that the mental is distinct from the physical. Therefore, if a given event has a complete physical cause, and the mental cause is distinct from this complete physical cause, then this supervening mental cause must be excluded. The physical cause does all of the work, so there is no work left over for the mental cause.
In this dissertation I consider and respond to Jaegwon Kim’s principle of causal/explanatory exclusion. I conclude that the most promising response to the problem generated from causal exclusion is to endorse what I call structuralism. Structuralism construes mental states as mereological structures, or configurations, of parts. Macro structure plays a role in determining which micro properties its parts will and will not instantiate, so there is a genuine role for the mental to play. The micro properties that are instantiated, however, do all of the causal work, so causal completeness is secured as well. This is a nonreductive position, since the mereological structure of the parts is not identical with the parts themselves. This model avoids the causal exclusion problem by noting that mereological relations are non-causal determinative relations, so mental states can play an important determinative role without contributing any causal power beyond what the causally sufficient micro properties of the parts contribute.
This solution to the problem of causal exclusion affords a solution to the parallel problem generated from the principle of explanatory exclusion as well. The principle of explanatory exclusion states that “there can be no more than a single complete and independent explanation for any one event” (Kim, 1988, p. 233). I resolve this difficulty by adopting a nuanced form of what is called the dual-explananda reply. Since the above reasoning suggests that mental states are distinct from physical events, we can conclude that mental explanations and physiological explanations do not refer to the same thing, so there is no exclusion pressure between the two explanations.
Moore, Dwayne, "The Problem of Causal/Explanatory Exclusion" (2010). Theses and Dissertations (Comprehensive). 1102.