In the history of philosophy "intuition" has been used primarily as a term for an intellectual, or rational, episode intimately tied to a priori knowledge. The term has sometimes been used in a broader way to include certain sensory episodes (appearances) and certain introspective episodes (e.g., inner awareness of the passage of time). In contemporary philosophy this broader use has fallen out of fashion (except among Kantians), and the narrower use prevails.

An intuition in this sense is simply a certain kind of seeming: For one to have an intuition that P is just for it to seem to one that P. This kind of seeming is intellectual, not sensory or introspective, in the following sense: Typically, if it is possible for someone to have the intuition that P, then it is possible for someone to have the intuition that P in the absence of...