Philosophers have used the term ‘consciousness’ for four main topics: knowledge in general, intentionality, introspection (and the knowledge it specifically generates) and phenomenal experience. This entry discusses the last two uses. Something within one’s mind is ‘introspectively conscious’ just in case one introspects it (or is poised to do so). Introspection is often thought to deliver one’s primary knowledge of one’s mental life. An experience or other mental entity is ‘phenomenally conscious’ just in case there is ‘something it is like’ for one to have it. The clearest examples are: perceptual experiences, such as tastings and seeings; bodily-sensational experiences, such as those of pains, tickles and itches; imaginative experiences, such as those of one’s own actions or perceptions; and streams of thought, as in the experience of thinking ‘in words’ or ‘in images’. Introspection and phenomenality seem independent, or dissociable, although this is controversial.
Phenomenally conscious experiences have been argued to be nonphysical, or at least inexplicable in the manner of other physical entities. Several such arguments allege that phenomenal experience is ‘subjective’; that understanding some experiences requires undergoing them (or their components). The claim is that any objective physical science would leave an ‘explanatory gap’, failing to describe what it is like to have a particular experience and failing to explain why there are phenomenal experiences at all. From this, some philosophers infer ‘dualism’ rather than ‘physicalism’ about consciousness, concluding that some facts about consciousness are not wholly constituted by physical facts. This dualist conclusion threatens claims that phenomenal consciousness has causal power, and that it is knowable in others and in oneself.
In reaction, surprisingly much can be said in favour of ‘eliminativism’ about phenomenal consciousness; the denial of any realm of phenomenal objects and properties of experience. Most (but not all) philosophers deny that there are phenomenal objects – mental images with colour and shape, pain-objects that throb or burn, inner speech with pitch and rhythm, and so on. Instead, experiences may simply seem to involve such objects. The central disagreement concerns whether these experiences have phenomenal properties – ‘qualia’; particular aspects of what experiences are like for their bearers. Some philosophers deny that there are phenomenal properties – especially if these are thought to be intrinsic, completely and immediately introspectible, ineffable, subjective or otherwise potentially difficult to explain on physicalist theories. More commonly, philosophers acknowledge qualia of experiences, either articulating less bold conceptions of qualia, or defending dualism about boldly conceived qualia.
Introspective consciousness has seemed less puzzling than phenomenal consciousness. Most thinkers agree that introspection is far from complete about the mind and far from infallible. Perhaps the most familiar account of introspection is that, in addition to ‘outwardly perceiving’ non-mental entities in one’s environment and body, one ‘inwardly perceives’ one’s mental entities, as when one seems to see visual images with one’s ‘mind’s eye’. This view faces several serious objections. Rival views of introspective consciousness fall into three categories, according to whether they treat introspective access (1) as epistemically looser or less direct than inner perception, (2) as tighter or more direct, or (3) as fundamentally non-epistemic or nonrepresentational. Theories in category (1) explain introspection as always retrospective, or as typically based on self-directed theoretical inferences. Rivals from category (2) maintain that an introspectively conscious mental state reflexively represents itself, or treat introspection as involving no mechanism of access at all. Category (3) theories treat a mental state as introspectively conscious if it is distinctively available for linguistic or rational processing, even if it is not itself perceived or otherwise thought about.
