Abstract– In the philosophy of mind functionalism, in contrast with identity theory, claims that mental state types are not reducible to physical state types. This claim relies on the concept of multiple realizability of the mental states, which was introduced by Hilary Putnam. This paper analyzes identity theory, the concept of multiple realizability and different types of functionalism and shows that functionalism is consistent with identity theory. Keywords: brain states, identity, multiple realizability, mental states, reducibility I. INTRODUCTION According to the identity theory mental states are identical with brain states. On the other hand functionalism claims that mental states are multiply realizable and for this reason mental states cannot be identified with any particular physical state type. The functionalists hold that what makes something a mental state is not its internal physical constitution; what makes something a mental state is its causal role it plays in the cognitive system of which it is a part. It has been commonly held that functionalism is incompatible with identity theory. This paper aims to show that functionalism is consistent with identity theory. In doing so, I will analyze identity theory, the concept of multiple realizability and different forms of functionalism and examine whether functionalism is incompatible with identity theory or not. II. IDENTITY THEORY Place (1956), in his paper "Is Consciousness a Brain Process?", has claimed that the sensations and the like might very well process in the brain. Place admits that the statements about sensations cannot be translated or logically analyzed into statements about brain processes, but that does not necessarily imply that consciousness is not a brain process. While defending that consciousness is brain process, he is not claiming that it is necessarily true, but that it is not necessarily false and thus it is a defensible position. He maintains that the view that an assertion of identity between consciousness and brain process can be ruled out only on logical grounds alone is the result of a failure to distinguish between two senses of the word ‘is’, the ‘is' of definition and the ‘is’ of the composition. According to Place, the ‘is’ of definition is used in phrases like "Red is a color." It is necessarily the case that if something possesses the left quality, then it also possesses that on the right- all red things are also colored. The other sense of ‘is’, that is, the ‘is’ of the composition is used in the phrase like "His table is an old packing-case." Here, being a table does not necessarily mean being a packing case. It is just in this situation; it is the case that the object is both a table and a packing-case. In both the cases of definition and composition, either side of the ‘is’ statements adequately characterizes the situations (1956, p-45). According to Place (1956) those who dismiss that consciousness is a brain process on logical grounds alone assume that if the meanings of two expressions are not connected, they cannot both adequately characterize the same object. Those philosophers seem to be operating under the assumption that since there would be nothing self- contradictory in saying that one could have a pain without anything going in the brain, it is necessary that consciousness cannot be brain processes. Place disagrees with this point by referring to the table-packing-case. Though there is nothing self-contradictory in assuming that something can be a table without being a packing-case, it is fallacious to claim that tables can never be packing-case. Place (1956) maintains that in those cases where the technical or scientific observations can both corroborate and explain the views of an unequipped observer, we can take these two observations are of the same event. In the case of lightning, science tells us that particular motions of electric charges create the kind of visual stimulation that a human would report as lightning. He argues that to identify consciousness and brain processes we have to represent what an introspecting subject says about his particular conscious experience, is not inconsistent with what a physiologist says about the brain process of the subject when he (the subject) is having that particular experience. Place urges that we must be careful to avoid the phenomenological fallacy, which rests on a mistaken assumption that when we describe an object, we describe our conscious experience of that object since our ability to describe an object depends on our being conscious of that object. According to place, the thing is quite the opposite- when we describe an object, we describe it concerning the real properties of the object which would normally lead to a conscious experience, even if that is not the case at the moment. (Consider a phantom green dot in your vision– there is nothing actually 'green' about it except that is causing you the same experience that a real green object would.) According to Place (1956) what an introspecting subject says about his conscious experience and what a physiologist says about the brain process of the subject while having that experience are not descriptions of two different events or processes, rather they are descriptions of one and the same IDENTITY THEORY, MULTIPLE REALIZABILITY OF MENTAL STATES AND FUNCTIONALISM Mahmuda Akand, Assistant Professor, Department of Philosophy, Jahangirnagar University Email: mahmudaakand@gmail.com