Relation to the world· Mind and consciousness
Physicalism
Axis: The enigma of consciousness — Is lived experience something more than the structure and functioning of the brain?
Consciousness is nothing but the brain's activity: experience is not a further fact added to the brain's workings, it is part of them, however hard it may be to explain. How remains to be understood, which most take to be a difficulty of research rather than a mystery of principle. The pole gathers several shades: identity theory, for which every mental state will one day be identified with a brain state, and biological naturalism, for which consciousness is a feature of the brain as ordinary as digestion, irreducible to a third-person description without being one more ingredient in the world. Whether that reduction succeeds is settled on ; whether the substrate must be biological, on .
Movements 1
Epicureanismexplicit
The soul is corporeal: an assembly of very fine atoms that dissolves at death like the rest. Thought and sensation are material processes, with nothing immortal or immaterial.
Epicurus, Letter to Herodotus; Lucretius, On the Nature of Things, III
Philosophers 2
Smartexplicit
Smart argues that sensations are not merely correlated with brain processes: they are identical to them, as lightning is an electrical discharge. This identity theory rests on a principle of economy: if everything else in the living world is explained in physico-chemical terms, making consciousness the sole exception would force us to admit dangling laws, with no role in the edifice of science. It is objected that one can know one's own sensation while knowing nothing of the brain: he answers with a topic-neutral analysis, saying "I have an orange after-image" amounting only to saying that something is going on in me like what goes on when I see an orange. The statement says nothing of the nature of that "something", and nothing forbids its being a brain process.
"Sensations and Brain Processes" (1959) · Philosophy and Scientific Realism (1963)
Searleexplicit
Searle holds consciousness to be an ordinary biological phenomenon, on a par with digestion or photosynthesis: it is caused by low-level neuronal processes and realized in the brain as a higher-level property. That a state is lived in the first person does not entail that it is immaterial: its mode of existence is subjective, its nature remains biological. This biological naturalism refuses both inherited camps, the that makes mind another substance, and the that, to save objectivity, end up treating lived experience as negligible. His critics reply that an irreducibility of principle brings him despite himself close to property dualism: he disputes this by distinguishing causal reduction, which he grants since the brain does produce consciousness, from ontological reduction, which would delete the first-person point of view instead of explaining it. This is what settles his place here: the irreducibility he maintains is indeed that of the subjective character of experience, which he holds to be a first-person ontology, but it does not make consciousness a property added to the brain. For him consciousness is a way the brain itself is, at a higher level, not one more ingredient in the inventory of the world.
"Minds, Brains, and Programs" (1980) · The Rediscovery of the Mind (1992)
Argument
- Every known variation in mental life tracks a variation in the brain: anaesthesia, lesion, alcohol, fatigue, a child's development. We know of no case of lived experience without a cerebral substrate, nor of any sizeable cerebral change without an echo in what is lived.
- Our mental states have physical effects: my pain makes me cry out, my decision raises my arm. To deny it is to turn mental life into an , a spectacle with no purchase whatever on our acts.
- Yet the physical world is , that is, every physical effect already has a sufficient physical cause: the cry is explained entirely by a chain of nerves and muscles, with no remainder and no gap where something else might slip in.
- If the cry already has a sufficient physical cause and my pain causes it too, only two exits remain: either it is caused twice over, by a systematic and inexplicable overdetermination, or my pain is nothing other than that cerebral state, which is what identity theory holds.
Therefore So consciousness is not one more ingredient set beside the brain: it is the brain at work. How remains to be understood, which is a difficulty of research and not a mystery of principle.
See the pageObjectionAttacks the reasoning
- The argument establishes at best that mental and cerebral states are correlated and occupy the same place in the chain of causes. Yet a correlation, however perfect, is not yet an identity: two inseparable things may still be two, and one may hold that the mental on the cerebral without concluding that they are one.
- In science's successful identifications, identity comes with an explanation: once molecular agitation is understood, one sees why that amounts to heat, and one can no longer conceive of heat without it.
- Nothing of the sort here: knowing everything about the circuitry of pain, the question "but why does it hurt?" stays open and perfectly intelligible. An explanatory gap remains that no other scientific identification has left behind it.
- The causal argument cannot decide between the two possible readings of that gap, provisional or final: it treats experience as a causal link, whereas it is precisely its qualitative face, the , that raises the problem.
Therefore The argument proves that experience is moored to the brain, not that it reduces to it: physicalism here remains a promise, the promise that one day the gap will close.
See the pageObjectionAttacks the position Thought experiment
- Mary knows every physical fact about colour vision, down to the last cerebral circuit, without ever having seen anything but black and white.
- On coming out, she sees a red rose and learns what it is to see red: something she did not know, and that no further physical information would have given her.
- If experience were identical with the cerebral state, she would have nothing to learn: she already possessed, in principle, the complete description of that state.
Therefore So experience is not exhausted by the brain's workings: a fact remains that the complete physical description did not contain.
See the page- Descriptive Thought experimentWhat it is like
There is something it is like to be me, and nothing of the sort, presumably, for a stone. But is that "something" one more reality in the world, which physical description lets slip, or only a limit of ours, unable as we are to occupy another's point of view?
a being's point of view - Descriptive Thought experimentMary's room
A scientist knows everything physics can say about colour, without ever having seen any: the day she sees red, does she learn something? If she does, lived experience would be one more fact, which objective knowledge did not contain; if not, one must say what she gains while learning nothing.
a lived experience - DescriptiveThe philosophical zombie
Imagine a double physically identical to you, acting and speaking as you do, but feeling nothing: no one home inside. If such a double is even conceivable, matter does not suffice to fix experience; but does what we can imagine prove anything about what is possible?
a double without experience - DescriptiveThe knot of mind and body
My decision raises my arm, a glass of wine muddles my thinking. But if the mind is not material, how does it act on muscles; and if the physical order is self-sufficient, does experience change anything at all in what happens?
the reciprocal action of mind and body - DescriptiveBeing wrong about what one feels
I can be wrong about the world, and even about my own motives, but about my very pain? It seems the one point where seeming and being coincide. What if that very obviousness were the best-installed illusion of all, a brain representing to itself an inner life as it believes it to be?
one's own experience - DescriptiveMinds other than my own
I never perceive another's experience, only bodies behaving: how do I know there is someone behind them? The only consciousness I have direct testimony of is my own.
access to another's experience - DescriptiveWhere does consciousness begin?
Does a dog suffer as I do? And a fish, an oyster, an embryo, a plant, a thermostat? Between what undergoes something and what undergoes nothing, is there a sharp threshold, a continuous slope, or is the question ill-posed? Whoever refuses to extend experience to all matter owes a criterion, and quantifying it is one way of paying that debt.
the distribution of consciousness in nature - DescriptiveWhat physics leaves blank
Physics describes matter by what it does: a mass resists, a charge attracts. Each term refers to another and never to what the thing is in itself. Does that blank await an answer, or is the question of the world's fabric a false need?
the fabric of the material world - DescriptiveWhat holds experience together
At every moment I see, hear and think at once, yet all of it comes to me as a single experience. What holds it together? When the bridge between the two hemispheres is severed, one and the same brain seems to host two streams of experience that ignore each other.
the unity of the field of consciousness - DescriptiveThe instrument or the source
A glass of wine, a lesion, age: the body alters thinking down to character itself. Does this dependence prove that the mind is bodily through and through, or only that its instrument is damaged, like a musician with a broken violin?
the mind's dependence on the body - DescriptiveIs emerging explaining?
The most common answer today: consciousness "emerges" from the brain as life emerged from chemistry. But is naming an emergence explaining how experience can arise from what has none?
the passage from neurons to experience