The philosophy of mind covers all philosophical topics pertaining to the mind and mental states. Its subtopics can be divided in two main ways. First, by the traditional divisions drawn between kinds of mental states: consciousness, intentionality, perception, and other states and processes. Second, by the types of philosophical questions asked about these activities: especially metaphysical questions that have to do with their nature (especially the relation between the mental and the physical) and epistemological questions that have to do with our knowledge of them. The philosophy of mind also overlaps with the philosophy of cognitive science and the philosophy of action.
Philosophy is often concerned with the most general questions about the nature of things: What is the nature of beauty? What is it to have genuine knowledge? What makes an action virtuous or an assertion true? Such questions can be asked with respect to many specific domains, with the result that there are whole fields devoted to the philosophy of art (aesthetics), to the philosophy of science, to ethics, to epistemology (the theory of knowledge), and to metaphysics (the study of the ultimate categories of the world). The philosophy of mind is specifically concerned with quite general questions about the nature of mental phenomena: what, for example, is the nature of thought, feeling, perception, consciousness, and sensory experience?
These philosophical questions about the nature of a phenomenon need to be distinguished from similar-sounding questions that tend to be the concern of more purely empirical investigations—such as experimental psychology—which depend crucially on the results of sensory observation. Empirical psychologists are, by and large, concerned with discovering contingent facts about actual people and animals—things that happen to be true, though they could have turned out to be false. For example, they might discover that a certain chemical is released when and only when people are frightened or that a certain region of the brain is activated when and only when people are in pain or think of their fathers. But the philosopher wants to know whether releasing that chemical or having one’s brain activated in that region is essential to being afraid or being in pain or having thoughts of one’s father: would beings lacking that particular chemical or cranial layout be incapable of these experiences? Is it possible for something to have such experiences and to be composed of no “matter” at all—as in the case of ghosts, as many people imagine? In asking these questions, philosophers have in mind not merely the (perhaps) remote possibilities of ghosts or gods or extraterrestrial creatures (whose physical constitutions presumably would be very different from those of humans) but also and especially a possibility that seems to be looming ever larger in contemporary life—the possibility of computers that are capable of thought. Could a computer have a mind? What would it take to create a computer that could have a specific thought, emotion, or experience?