The problem with qualities is that they are about how something shows itself to us, about how something feels to us, and they seem to involve more than can be structurally discriminated by concepts. Qualities are not reducible to the abstractions by which we try to distinguish them. Consequently, to the extent that philosophies of mind and language focus only on conceptual and propositional structures and the inferences supported by those structures, they lack an adequate way to investigate the role of qualities in meaning and thought. It is no surprise, therefore, that qualities, just like emotions, are typically underappreciated in philosophical theories of meaning. Because we cannot capture qualitative experience in propositions with subject-predicate structure, we tend to downplay the importance of qualities as part of meaning. We mistakenly regard something that is only a conceptual limitation (i.e., our inability to adequately conceptualize qualities) as though it were actually a limitation on our experience of meaning itself. Many recent philosophical discussions of cognitive science make reference to the problem of qualia, which are felt qualities, like the blueness of a blue sky or the silkiness of a silk dress or the smell of summer lilacs. The problem is that qualia cannot be reduced to conceptual structures or to functional states of an organism. This fact is supposed to be a showstopper for any attempt to give a naturalistic account of concepts, meaning, and experience.

Mark Johnson, The Meaning of the Body: Aesthetics of Human Understanding