How is it possible for a part of the natural world to ask this question?
There seems to be a tension between what our best physical theories say about the natural world and consciousness. Indeed, it's not clear how consciousness can be made to fit in any physical theory.
The Hard Problem of Consciousness
X is phenomenally conscious (alt. X has conscious experiences) iff there is something it is like to be X
"How and why do physical processes give rise to experience?"
The Solution Space
Contrast two kinds of explanation:
Reductive Explanation: An explanation which makes no appeal whatsoever to consciousness.
Non-Reductive Explanation: An explanation in which principles about consciousness are used essentially.
Against two kinds of solution:
Materialist Solution: Consciousness is a physical process.
Non-Materialist Solution: Consciousness is a non-physical property.
| The Range of Possible Solutions | Materialist | Non-Materialist |
| Reductive | ||
| Non-Reductive |
Arguments Against Materialist Solutions
| The Explanatory Argument | |||
| 1 | Physical accounts explain at most structure and function. | ||
| 2 | Explaining structure and function does not suffice to explain consciousness. | ||
| ∴ | 3 | No physical account can explain consciousness. | 1&2 |
| The Conceivability Argument | |||
| Version 1 | |||
| 1 | It is conceivable that there be zombies. | ||
| 2 | If it is conceivable that there be zombies, then it is metaphysically possible that there be zombies. | ||
| 3 | If it is metaphysically possible that there be zombies, then consciousness is non-physical. | ||
| ∴ | 4 | Consciousness is non-physical. | 1,2&3 |
| Version 2 | |||
| Let P be the conjunction of all microphysical truths about the universe, and let Q be some phenomenal truth about the universe. | |||
| 1 | It is conceivable that P ^ -Q. | ||
| 2 | If it is conceivable that P ^ -Q, then it is metaphysically possible that P ^ -Q. | ||
| 3 | If it is metaphysically possible that P ^ -Q, then materialism is false. | ||
| ∴ | 4 | Materialism is false. | 1,2&3 |
| The Knowledge Argument | |||
| Version 1 | |||
| 1 | Mary knows all the physical facts. | ||
| 2 | Mary does not know all the facts. | ||
| ∴ | 3 | The physical facts do not exhaust all the facts. | 1&2 |
| Version 2 | |||
| 1 | There are truths about consciousness that are not deducible from physical truths. | ||
| 2 | If there are truths about consciousness that are not deducible from physical truths, then materialism is false. | ||
| ∴ | 3 | Materialism is false. | 1&2 |
| The General Argument: The Epistemic Gap | |||
| 1 | There is an epistemic gap between physical and phenomenal truths. | ||
| 2 | If there is an epistemic gap between physical and phenomenal truths, then there is an ontological gap, and materialism is false. | ||
| ∴ | 3 | Materialism is false. | 1&2 |
Type-A Materialism
There is no epistemic gap between physical and phenomenal truths.
Solving the easy problems of consciousness solves the hard problem.
Type-B Materialism
There is an unbridgeable epistemic gap between physical and phenomenal truths, but there is no ontological gap.
Type-C Materialism
There is an apparent epistemic gap which will eventually be closed.
If none of these brands of materialism succeed, then we are back to square-one. There seem to be two possibilities. Either consciousness is a fundamental part of the fabric of the physical universe, or it is necessitated by more fundamental features of the physical universe.
The problem with this is the integration of phenomenal properties in a causally closed physical universe.
Type-D Dualism
Deny that the universe is causally closed.
Type-E Dualism
Accept causal closure, but deny that phenomenal properties have any causal role.
Type-F Monism
Accept causal closure, and accept a causal role for phenomenal properties.