Philosophy of Mind

What it asks

There is something it is like to see red, to be in pain, to taste coffee. There is nothing it is like to be a stone.

The brain is a physical object, describable in the same terms as any other. Nothing in that description mentions what anything is like. Philosophy of mind asks how those two things fit together - whether the experience is the physical process described another way, something extra, or a confusion in how the question is put.

The second question is about thought rather than feeling. A belief is ABOUT something; it can be true or false of the world. No merely physical state is about anything, and how a brain state acquires that property is a distinct problem, sometimes harder than the first.

The recurring problems

The hard problem. Explaining how the brain processes information, controls behaviour and reports on itself is difficult but ordinary science. Explaining why any of that is accompanied by experience is a different kind of question, and no proposed answer looks like the answers science usually gives.

The knowledge argument. A scientist who knows every physical fact about colour vision but has only seen black and white learns something new on seeing red. If she does, physical facts were not all the facts. Every premise of this has been denied by someone.

Multiple realisability. Pain in a human, an octopus and possibly a machine would be the same state in different physical stuff, which suggests mental states are defined by what they DO rather than what they are made of - and that argument is what killed the identity theory.

Intentionality. Thoughts are about things, including things that do not exist. Nothing else in nature has that property, and naturalising it has resisted every attempt.

How it developed

Descartes made it a problem in 1641 by drawing the line sharply: mind is thinking substance, body is extended substance, and they are genuinely distinct. The objection was immediate and has never been answered - if they are that different, how does either affect the other?

Behaviourism tried to dissolve the question by identifying mental states with dispositions to behave. Ryle's The Concept of Mind in 1949 gave the philosophical version, arguing that Descartes had made a category mistake and invented a ghost in the machine.

The identity theory in the late 1950s said plainly that mental states ARE brain states. It was quickly undermined by multiple realisability, and functionalism replaced it: a mental state is defined by its causal role, whatever implements it. That is still the default position and it is what makes artificial minds conceivable in principle.

Then the objections arrived that functionalism handles worst. Nagel asked in 1974 what it is like to be a bat; Jackson set out the knowledge argument in 1982; Chalmers named the hard problem in 1995. None of them shows that physicalism is false, and all of them show that something has not been explained.

The positions within it

Substance dualism, property dualism, physicalism in identity and functionalist forms, eliminative materialism, panpsychism and mysterianism are the standing positions, all in the Schools section.

Panpsychism, that experience is a basic feature of matter, was for a century a byword for absurdity and is now argued seriously - not because the evidence changed but because the alternatives have proved so difficult.

Where it stands now

Physicalism remains the working assumption and the hard problem remains unsolved, which is an uncomfortable but stable position for a field to occupy.

The most active current work is on consciousness as an empirical target - global workspace and integrated information theories both propose testable markers - and on illusionism, which holds that the hard problem is hard because the phenomenon is not what it presents itself as being. That view is a minority one and the strongest thing to be said for it is that everything else is worse.