The Problems of Consciousness

Why is Consciousness a Hard Problem?

The problems of consciousness are difficult because of the essential innerness, the privateness, of subjective experience. This is a single difficulty that takes a variety of forms.

  • A single datapoint: Science relies on inference and generalization, on comparison, on data-gathering, on the evidence of the senses. But I have exactly one data-point on some of the most essential problems of consciousness: I experience my own consciousness, and I perceive what it is like to be me; but I can have no direct experience of anyone else's consciousness. It is hard to generalize reliably from such a paucity of data.
  • Opacity to physical instruments: Not only do I have no direct experience of anyone else's consciousness, but I know of no way to gather convincing indirect evidence. There is no physical observation or measurement that I know of whose results would constitute evidence for or against the hypothesis that anyone besides me has (or does not have) consciousness. (This is because, due to the fact that I have only a single datapoint to infer from, I have no reliable knowledge about the correlations between physical facts and subjective consciousness.)
  • Uniqueness: Consciousness is not like anything else. Everything else that I experience, I experience through consciousness, through subjective experience. The processes by which I come to know about things in the external world all operate through consciousness, through the having of certain experiences. These processes do not seem suited for giving me knowledge about consciousness itself.

These are, clearly, different but overlapping ways of thinking about the same essential problem. Some treatments of consciousness attempt to avoid this problem, in ways that we do not find particularly satisfying: see "Some unsatisfying answers" for discussion of some of these.

We eagerly solicit help in this endeavor; suggestions, corrections, ideas, and references may be sent via email to

David Chess accepts all the blame, but Steve White gets some of the credit. If you're lost, see the site map. This page last updated January 15th, 2000.