In investigating the mental states of animals, we will start with what seem to be simpler states and work our way to more complex ones. This chapter treats a cluster of mental states of interest to hedonistic utilitarians—mental states that are typically pleasant or unpleasant— as well as consciousness in general (and one nonmental state). We might, roughly, refer to this cluster of mental states as feelings. (As in Chapter 4, I will often use the term mental states as a shorthand for mental states, events, or processes.)

A PRELIMINARY MATTER

Thus far we have spoken of mental states without saying exactly what they are. Relying on an intuitive understanding of this concept is fine for most purposes, because people usually agree on which states are mental. But confusion is possible.

Dominating modern philosophy and still influential today, the Cartesian tradition takes consciousness to be the defining feature of the mental.From this view, there can be no unconscious mental states, by definition. (For convenience, I will use the term unconscious to modify all things that are not conscious, even never-conscious beings and their states.) Freudian psychology and other developments made a good case for reconstructing the concept of the mental such that consciousness was not strictly essential. One could have unconscious desires, for example, which might become conscious if certain causes of repression were removed. Freud aside, we now know that a great deal of information processing occurs outside of awareness.