Why do people exhibit particular behaviour towards a class of objects called artworks? That is the topic of study in aesthetics. This paper explores how various theories of aesthetics can be interpreted in the context of artworks generated by artificial intelligence systems, in particular those that are grounded in the idea of search as a means of implementing intelligence computationally. A number of aesthetic theories are explored, including ideas of imitation, skill, form, expression, imagination, and focus. The paper concludes by highlighting a number of areas that, in light of these considerations, have been neglected by the makers of computer art systems and which provide future opportunities in this area.