The term consciousness refers to several distinct, but related phenomena that figure in the mental functioning of people and other creatures.

Kinds of Consciousness

One of these phenomena is closely tied to simply being awake. An individual is conscious if it is awake and responsive to sensory stimulation; a person or other creature that is asleep, in a coma, or knocked out is not conscious.

There are also other phenomena we refer to as consciousness. One is conscious of something if one senses or perceives the thing or has some suitable thought about it; being conscious of something is being aware of that thing. Because we use a grammatical object to specify what somebody is conscious of, it is convenient to call this phenomenon transitive consciousness, as against an individual's being awake and responsive to sensory input, which we can call creature consciousness (Rosenthal 1990).

We sometimes describe the...