Michael 哲學論文讀後感 - “The Philosophy of Mind _ The nature of mental states – Hilary Putnam"

Author: Michael Hsu (許舜斌)
Date: 7/13/2006

Journal:
The problem of mind is an important issue in philosophy. After the scientific revolution, more and more people, philosophers and scientists, think that dualism is not substantial and mental states must be objective states, which are compatible with physical science. In the twentieth century, there are three important branches explaining the issue. In the first one, coming from logical positivism, they think a mental state can be analyzed in terms of behavioral patterns. The second one identifies brain states with mental states, and it is so called physicalism. The third one, which is the main topic of this paper, is functionalism, it identifies mental states with functional roles or functional states, whose idea comes from Turing Machine. Because functionalism needs to ground the functional state by behavioral patterns, it is an advanced version of behavioralism in this sense. So the debate in the philosophy of mind is turned to the debate between functionalism and physicalism, whether mental states go with physical properties or functional properties. But I think that before answering the debate we need to know what mental states or mental properties are. Consciousness is a taboo before the 1990s, so Putnam didn’t consider this one. I think losing consciousness or conscious properties is the same as losing the mind, so even if we can use objective terms, functional terms or behavioral terms, to explain mental states, we may lose this aspect.Putting aside this question, I think there is another point in the debate, which is the distinction between simulation and reality, because the main argument of this paper against physicalism is the argument from multiple realization. In other words, what are the limitations in computability? Only computable functions simulated in computers can’t be distinguished from reality; in other words, only computable functions can be realized in different physical properties. The contemporary view of computability based on Turing Machine, which is used in Putnam’ s paper, it defines what is computable. Based on Turing Machine, the computable function is limited in the domain of natural numbers. However, there are a lot of functions which are not in the domain of natural number, and a lot of functions, which describe phenomenon in physical world, are this kind of functions. This world may have a lot of important phenomenon which can’t be captured by the functions in the domain of natural number, and we can only use computers to simulate the function in the domain of natural number. So we can’t simulate the mind in this sense, we only can simulate (realize) mind in the same physical realizer. If it is reality, mind only can go with some specific physical property, which can realize this kind of function. However, whether we can extend the range of computability is another question.