Introduction to the philosophy of mind

Philosophy of mind is the philosophical study of the nature of the mind, mental events, mental functions, mental properties, and consciousness. These areas give rise to some very difficult problems and questions, and there are many opinions as to their solutions and answers. This article attempts to suggest the scope of the philosophy of mind and indicate some of the important questions, but does not provide answers.

What is the mind?
In order to engage in a meaningful discussion concerning mind and consciousness, it is necessary to arrive at a consensus concerning the mind's nature, as to whether the word mind refers simply to a collection of particular thoughts, feelings, and so forth, or to some entity over and above those particular thoughts, feelings, and so forth. From here, enquirers might incept investigations into the mind's nature and composition, as to whether it arises from a specialised composition of the same kind of substance as physical objects, or whether it is a different order of substance altogether (for example, the res cogitans of Descartes). From this analysis, other problems arise regarding the mind. If, for example, we suppose that the mind is some sort of mental substance, we might ask: is there some way to explain mental substance in terms of physical substance, or even vice versa? Furthermore, how might the two substances, given their entirely differing ontological nature, possibly relate (this is commonly referred to as the mind-body problem)?

This article does not propose to offer conclusive remarks concerning these debates, but to outline the broad trends of the debate, and the philosophical issues involved in their pursuit.

Mental events
In the case that it is supposed that the mind is not some mysterious substance, and it is held instead that there are only mental events and that "the mind" designates no more than a series of mental events, one can still inquire about the relation between mind and body in a different way, in terms of the relation between mental events and physical events. It might be supposed that mental events are totally different from physical events, in which case it becomes difficult to explain what mental events are in terms of physical events.

Alternatively, it might be supposed that mental events are somehow explicable as being the same as physical events - a view known as token-physicalism. For example, when John feels a particular pain P (at a particular time T), a particular mental event M is occurring (at a particular time T); now is that pain, P, even possibly the same as something that occurs in John's brain, such as the firing of some special group of neurons, M?

Mental properties
Another question commonly asked is whether mental properties (or states, or kinds, or [equivalently general term]) are just physical properties. Is the mental phenomenon we call 'pain' really just, say, firing C-fibers in the brain? This view is known as type-physicalism (or type-identity theory). A common argument against this view is known as the argument from multiple realizability: since animals we commonly attribute as being in pain have completely different neurophysiological systems, and thus completely different physical properties, it follows that pain cannot be one particular physical property, i.e., firing C-fibers found in humans. After all, surely dogs, other animals, and even reptiles are capable of feeling pain. (We could go as far as saying that aliens with utterly disparate physical systems are also, at least possibly, capable of feeling pain.). This type of argument is generally taken to be an argument against another related view known as scientific reductionism.

Reductionism
Identifying the mind with physical substances or properties is one direct form of materialism, and claiming that psychological theory (whichever flavour you wish) is reducible to scientific theory is another, albeit indirect, form of materialism. If we can show that all of psychology is reducible to neurophysiology, and in turn, neurophysiology is reducible all the way (perhaps via other special higher-order sciences, like chemistry) down to physics, then what we've shown is that mind is nothing above and beyond the physical. In effect, it is a two step process: i) reducing languages to each other ii) then claiming that the ontology (or objects) of the reduced science (psychology) is identical to the ontology of the reducing science (neurophysiology).

However, as has been pointed out by Max Velmans in his 2000 work Understanding Consciousness, reductionism fails to account for Leibniz's law. That is, that for A to be identifiable with B, the properties of A must be the same as the properties of B; they must be ontologically symmetrical. Reductionists claim that brain states are the causes or the correlations of consciousness: the neural configurations of the brain are either the inceptors of subjective consciousness, or they are the physical states of what is subjectively experienced as consciousness. Thus, neural brain states, reductionists argue, are ontologically identical to consciousness.

However, neither of these assertions stands up to rigorous analysis. For example, human height correlates with human weight, but their properties are not identical. On the other hand, a stone thrown into a pond causes ripples on the surface of the water, but the properties of the thrown rock are entirely unlike the properties of the rippling water. Given this, Velmans argues, it is difficult to see how reductionism can be "made to work".

Functionalism
As alluded to above, many philosophers accept the thrust of the multiple realizability argument and thus reject both physicalism and reductionism wholesale. The argument has motivated another view known as functionalism which holds that mental states aren't physical, rather, they're functional. A functional state describes a relationship between certain inputs (sensory stimuli), outputs (behavior), and other mental states. A pain is functional in virtue of having a certain causal role. That causal role is determined by certain input stimuli and mental states, and determines future behavior and mental states. So although pain may not be identical to some one (first-order physical property like) firing C-fibers, it's at least identical to some (higher-order) functional state F. Generally, functional states are specified in terms of Turing machines states, which are completely describable by Turing machine tables. And so, one version of functionalism, machine-functionalism, identifies mental states with Turing machine states. Arguments such as Putnam's Twin Earth thought experiment, and Lucas' Godelian argument have been the forerunners against functionalism.

So far we've presented several different questions that the philosophy of mind asks: What is the mind, a substance or just a series of mental events? Is the mind somehow reducible to, or explainable in terms of, the body? Are mental events somehow reducible to, or explainable in terms of, physical events? Each of these questions are ways of interpreting the more ambiguous questions we started with, such as, "What is the mind?" and "What are mental events?"

What is involved in each type of cognitive process?
We can also ask questions about the different specific cognitive processes, and of course we might ask what cognitive processes in general are supposed to be. In that case, we'd be asking what distinguishes a cognitive process from any other kind of process. That is another way of putting the mind-body problem. We can also ask a series of more specialized questions, about each individual cognitive process. We can get the answers through cognitive science.

Take perception as an example. Philosophers ask what is going on when we perceive something -- when we see, hear, taste, touch, and so on. But philosophers are not interested in the particular mechanisms that allow us to see -- for example, they do not study the shape of the eye or how the optical nerve carries information to the brain. They are interested in even more basic questions. They ask: Do we perceive physical objects directly with our senses, or do we form mental images of some sort, which we use to represent physical objects and their properties? These are questions raised by the philosophy of perception. The philosophy of perception is all about how our minds come in contact with the world outside our minds.

Another example is the will, or volition. When we choose to do something we are using our wills, or engaging in volition. There is, of course, one special and very difficult question that philosophers ask about this process, namely, is the will free? If Mary decides to walk across the room, that seems to be entirely up to her; she could have chosen otherwise. But if the universe is determined, and especially if our will really is after all just a physical process, then it certainly does seem as though Mary didn't have control over everything that led up to her deciding to walk across the room. So was she free or wasn't she?

See also Free will and determinism.

What is consciousness?
Consciousness is one of the most problematic areas of modern philosophy and neuroscience. From the perspective of the naïve or direct realist it is simply the processes that occur in the brain between stimulus and response. The issue is, however, far more complex than this, for instance in imagining, lucid dreaming and dreaming the subject seems to be perceiving brain activity and modern MRI studies show that similar areas of brain are used for perception, imagination and dreaming. How does the brain see its own activity? Would this require an absurd little man or homunculus in our heads? Or is there some fascinating phenomenon or process at work? This is just one of many problems associated with the study of consciousness. See the link to consciousness for more information.

Frame issues
A final class of questions emerging from this aspect of philosophy concern the validity of the commonsense categories employed. Must it be the case that determinism rules out free will, or is it that one or both of these categories has been poorly defined? Does the rule against multiplication of entities force materialists to exclude higher-order entities such as semantic systems, or have we endowed 'material' with unwarranted properties? Is the term 'natural' meaningful if we deny that it has an opposite? What precisely is an event?

See also How the Self Controls Its Brain. For a more science-based model of how the mind works, see neural networks, reinforcement learning, complex mind.

Philosophers of mind

 * G. E. M. Anscombe
 * D. M. Armstrong
 * Ansgar Beckermann
 * William Bechtel
 * Ned Block
 * Tyler Burge
 * David Chalmers
 * Roderick Chisholm
 * Noam Chomsky
 * Patricia Churchland
 * Paul Churchland
 * Andy Clark
 * Francis Crick
 * Donald Davidson
 * Daniel Dennett
 * Fred Dretske
 * Gerald Edelman
 * Gareth Evans
 * Owen Flanagan
 * Jerry Fodor
 * Tim van Gelder
 * Alvin Goldman
 * Stuart Hampshire
 * Gilbert Harman
 * Jennifer Hornsby
 * Frank Jackson
 * Jaegwon Kim
 * Keith Lehrer
 * David Lewis
 * William Lycan
 * Norman Malcolm
 * Merab Mamardashvili
 * John McDowell
 * Colin McGinn
 * Maurice Merleau-Ponty
 * Thomas Metzinger
 * Thomas Nagel
 * David Papineau
 * Christopher Peacocke
 * Hollibert E. Phillips
 * Hilary Putnam
 * Anthony Quinton
 * Georges Rey
 * Richard Rorty
 * John Searle
 * Wilfrid Sellars
 * Sydney Shoemaker
 * J. J. C. Smart
 * Ernest Sosa
 * Robert Stalnaker
 * Michael Tye
 * Max Velmans
 * John Wisdom