Philosophy of global problems contains functionalism, nonreductive physicalism and Eliminative materialism. Functionalism was formulated by Hilary Putnam and Jerry Fodor as a reaction to the inadequacies of the identity theory. Putnam and Fodor saw mental states in terms of an empirical computational theory of the mind. At about the same time or slightly after, D.M. Armstrong and David Lewis formulated a version of functionalism which analyzed the mental concepts of folk psychology in terms of functional roles. Finally, Wittgenstein's idea of meaning as use led to a version of functionalism as a theory of meaning, further developed by Peter Sellars and
What all these different varieties of functionalism share in common is the thesis that mental states are essentially characterized by their causal relations with other mental states and with sensory inputs and behavioral outputs. That is, functionalism quantifies over, or abstracts away from, the details of the physical implementation of a mental state by characterizing it in terms of non-mental functional properties. For example, a kidney is characterized scientifically by its functional role in filtering blood and maintaining certain chemical balances. From this point of view, it does not really matter whether the kidney be made up of organic tissue, plastic nanotubes or silicon chips: it is the role that it plays and its relations to other organs that define it as a kidney. 
Many philosophers hold firmly to two essential convictions with regard to mind–body relations:
1. Physicalism is true and mental states must be physical states.
2. All reductionist proposals are unsatisfactory: mental states cannot be reduced to behavior, brain states or functional states.
Hence, the question arises whether there can still be a non-reductive physicalism. Donald Davidson's anomalous monism is an attempt to formulate such a physicalism.
The idea is often formulated in terms of the thesis of supervenience: mental states supervene on physical states, but are not reducible to them. "Supervenience" therefore describes a functional dependence: there can be no change in the mental without some change in the physical.
If one is a materialist but believes that all reductive efforts have failed and that a non-reductive materialism is incoherent, then one can adopt a final, more radical position: eliminative materialism. Eliminative materialists maintain that mental states are fictitious entities introduced by everyday "folk psychology". Should "folk psychology", which eliminativists view as a quasi-scientific theory, be proven wrong in the course of scientific development, then we must also abolish all of the entities postulated by it. Eliminativists such as Patricia and Paul Churchland often invoke the fate of other, erroneous popular theories which have arisen in the course of history. For example, the belief in witchcraft turned out to be wrong and the consequence is that most people no longer believe in the existence of witches.
Linguistic criticism of the mind–body problem
Each attempt to answer the mind–body problem encounters substantial problems. Some philosophers argue that this is because there is an underlying conceptual confusion. Such philosophers reject the mind–body problem as an illusory problem. Such a position is represented in analytic philosophy these days, for the most part, by the followers of Ludwig Wittgenstein and the Wittgensteinian tradition of linguistic criticism. The exponents of this position explain that it is an error to ask how mental and biological states fit together. Rather it should simply be accepted that humans can be described in different ways - for instance, in a mental and in a biological vocabulary. Illusory problems arise if one tries to describe the one in terms of the other's vocabulary or if the mental vocabulary is used in the wrong contexts. This is the case for instance, if one searches for mental states of the brain. The brain is simply the wrong context for the use of mental vocabulary - the search for mental states of the brain is therefore a category error or a pure conceptual confusion.
Today, such a position is often adopted by interpreters of Wittgenstein such as Peter Hacker. However, Hilary Putnam, the inventor of functionalism, has also adopted the position that the mind–body problem is an illusory problem which should be dissolved according to the manner of
Naturalism and its problems
The thesis of physicalism is that the mind is part of the material (or physical) world. Such a position faces the fundamental problem that the mind has certain properties that no material thing possesses. Physicalism must therefore explain how it is possible that these properties can emerge from a material thing nevertheless. The project of providing such an explanation is often referred to as the "naturalization of the mental." What are the crucial problems that this project must attempt to resolve? The most well-known are probably the following two:
Many mental states have the property of being experienced subjectively in different ways by different individuals. For example, it is obviously characteristic of the mental state of pain that it hurts. Moreover, your sensation of pain may not be identical with mine, since we have no way of measuring how much something hurts or describing exactly how it feels to hurt. Where does such an experience (qualia) come from? Nothing indicates that a neural or functional state can be accompanied by such a pain experience. Often the point is formulated as follows: the existence of cerebral events, in and of themselves, cannot explain why they are accompanied by these corresponding qualitative experiences. Why do many cerebral processes occur with an accompanying experiential aspect in consciousness? It seems impossible to explain.
Yet it also seems to many that science will eventually have to explain such experiences. This follows from the logic of reductive explanations. If I try to explain a phenomenon reductively (e.g., water), I also have to explain why the phenomenon has all of the properties that it has (e.g., fluidity, transparency). In the case of mental states, this means that there needs to be an explanation of why they have the property of being experienced in a certain way.
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What do you know about naturalism and its problems?
Why do many cerebral processes occur with an accompanying experiential aspect in consciousness?