Property dualism

1. To explain, in science, is to show by what mechanism a function is carried out: how the organism discriminates colours, memorizes, controls its behaviour, reports on its own states. These easy problems, as they are called by contrast, are hard, but we know what their solution would look like.
2. Suppose them all solved, down to the last circuit. One question remains, perfectly intelligible, and it is the hard problem: why is all that work accompanied by experience? One can describe a system that discriminates, memorizes and reports without yet having said what it is like for it.
3. When a question stays open although the explanation has said all it could say, its object was not what that explanation described: structure and function do not contain experience.
4. Yet experience varies strictly with the state of the brain, and no one dreams of denying it: that dependence is as solid a fact as the gap.

Therefore So experience is a further fact about the world, irreducible yet tied to the brain by a law of nature: a dualism without miracle, where nothing is added to matter but what it regularly produces.

1. The argument moves from "I conceive a double without experience" to "such a double is possible", then to "experience is not physical". Everything turns on the first move.
2. Yet one could conceive, without contradiction, water that was not H₂O: it was nonetheless impossible, water being H₂O wherever there is water. What we conceive depends on what we know, not on what is.
3. If experience is a cerebral state, conceiving a brain without experience amounts to conceiving a thing without itself: the description's apparent coherence comes from our having two distinct concepts of it, grasping that state in two ways, from outside by measurement and from inside by living it, without yet knowing it is the same.
4. The argument therefore assumes, without showing it, that whatever is imagined without contradiction can exist: its conclusion is already lodged in its premise.

Therefore The zombie proves nothing until that step is justified: the gap may lie only in our concepts, between two ways of grasping one and the same state.

1. This position grants the causal closure of the physical world, self-sufficient as it is: no neuron waits on experience to fire, and that is what allows it to call itself naturalistic.
2. It follows that experience is a mere epiphenomenon, doing nothing: my cries, my gestures, and even my words about my pain are explained without it, by the nervous machinery alone.
3. Yet I do speak of my experience, I marvel at it, I write books about the hard problem. Those behaviours therefore have, by the position's own lights, entirely physical causes.
4. My conviction that there is experience therefore does not come from experience: it would be exactly the same were there none, since the zombie, physically identical, also declares it has a feel and marvels at it.

Therefore Either experience acts, and the closure of the physical world must be given up; or it does not, and the testimony on which the whole position rests is cut off from what it testifies to.