I. Definition. Qualia are the phenomenal qualities of experiences—the raw felt qualities of sensations, emotions, thoughts, or anything else.
Emotions (like anger, envy, or fear) and moods (like euphoria, ennui, or anxiety) are also usually taken to have qualitative aspects. Qualia are often referred to as the phenomenal properties of experience, and experiences that have qualia are referred to as being phenomenally conscious.
C.S. Peirce seems to have had something like this in mind when he introduced the term ‘quale’ into philosophy in 1866 (1866/1982, para 223). There are more restricted uses of the term ‘qualia’, however. (2) Qualia as properties of sense data. Consider a painting of a dalmatian.
Epiphenomenal Qualia: Qualia that have no physical effect on anything (therefore no evolutionary function); this proposal assumes that not having qualia wouldn’t make a functional difference to anyone.