In the Stanford Encyclopedia of Philosophy. Edited by Edward Zalta (http://plato.stanford.edu) June 2002 (revised December 2006).
To say one has an experience that is conscious (in the phenomenal sense) is to say that one is in a state of its seeming to one some way. In another formulation, to say experience is conscious is to say that there is something it's like for one to have it. Feeling pain and sensing colors are common illustrations of phenomenally conscious states. Consciousness has also been taken to consist in the monitoring of one's own states of mind (e.g., by forming thoughts about them, or by somehow "sensing" them), or else in the accessability of information to one's capacities for rational control or self-report. Intentionality has to do with the directedness or aboutness of mental states — the fact that, for example, one's thinking is of or about something. Intentionality includes, and is sometimes taken to be equivalent to, what is called ‘mental representation.’
It can seem that consciousness and intentionality pervade mental life — perhaps one or both somehow constitute what it is to have a mind. But achieving an articulate general understanding of either consciousness or intentionality presents an enormous challenge, part of which lies in figuring out how the two are related. Is one in some sense derived from or dependent on the other? Or are they perhaps quite independent and separate aspects of mind?
Sections (1) and (2) offer introductory accounts of what is meant by ‘consciousness’ and ‘intentionality,’ with sensitivity to the difficulties raised by their varying interpretation. Then, influential perspectives on intentionality that have emerged in both phenomenological (Section 3) and analytic (Section 4) philosophical traditions are sketched, so as to highlight basic issues about the relationship of consciousness and intentionality, and provide some of the background against which they have been understood. Sections (5) through (8) survey some contemporary views about consciousness, considering their implications for the connection between consciousness and intentionality. Section (9) distinguishes four broad options for understanding their relationship, and closes with some observations about the philosophical consequences of choosing among them.