John Searle'ün bilinç teorisinde zihinsel nedensellik problemi

John Searle has developed an innovative and influential theory of mind that he calls "Biological Naturalism" in his book The Rediscovery of the Mind (1992). It is influential because Searle deals with problems on consciousness in a similar way as philosophers or scientists deal with problems on higher-level properties in other scientific fields, especially in the special sciences. He does not attribute a special status to them since he regards these problems as tractable. It is innovative because Searle offers a suggestion for how we can place consciousness in the scientific world by saving its subjective and qualitative character. Such advantages make Biological Naturalism a theory of mind that is worth investigating. Searle has two main claims: First, consciousness having irreducible properties such as subjectivity and qualitativity is caused by brain processes. Second, conscious states are causally efficacious. Searle faces the problem of mental causation due to these claims. The problem of mental causation is the difficulty in explaining how consciousness, which cannot be reduced to physical processes, interacts with the physical world without violating the laws of physics. This dissertation focuses on the examination of Searle's solution to the problem of mental causation within the non-reductionist framework. My ultimate aim is not to claim that he offers a complete account of mental causation, but rather to show under what conditions his account can be considered correct. In the first chapter, after introducing Biological Naturalism, I will discuss in what ways it differs from materialist and dualist theories. My aim in this chapter is to clarify Searle's position in the philosophy of mind to provide a basis for the discussions in the second and third chapters. In chapter 2, I will discuss Searle's claim "we know as a fact that the brain processes cause consciousness". What we know as a fact is that there is a correlation between the brain states and conscious states. Correlation between two events is necessary for causation, but not sufficient. Searle cannot provide direct evidence of why brain processes cause consciousness aside from being correlated to it. Furthermore, he cannot offer a method to test his claim. In this section, I will argue that the most appropriate model to test Searle's causal claim is the interventionist model of causation developed by Woodward. Lastly, I will show that even if we use the interventionist model of causation, we cannot interpret the relation between brain and consciousness as causation. In chapter 3, my aim is to examine Searle's claim "mental states are causally efficacious". However, the exclusion argument developed by J. Kim suggests that mental causes are excluded because underlying physical causes do all causal work. Otherwise, the effect is overdetermined by more than one cause, then non-reductionist physicalists have to overcome the overdetermination problem. The key issue of this chapter is to evaluate Searle's solution to the exclusion problem. I will show that Searle cannot get rid of the overdetermination problem as long as he regards the relation between brain and consciousness as causal, so he has no solution for the exclusion problem. My specific claim is: If we hold the supervenience relation between the brain and consciousness as non-casual, not only the solution proposed by Searle can be accepted but also this solution can be supported with current strategies such as compatibilism (Bennett 2003, 2008) and interventionism (Woodward 2003, Shapiro & Sober 2007).