Required Texts
 
Plato.  The Republic of Plato, translated by Francis   McDonald Cornford.  ISBN: 0-19-500364-0. (The Jowett translation is freely available, but it is no substitute for the aforementioned hardcopy.)
 
Descartes, René.  Meditations on First Philosophy, translated by Donald A. Cress.  (Trilingual HTML edition is something you can check out if you are interested, but it's not a substitute for the hard copy, which you will need.)

Required Readings on Reserve or Online

Hume, D. Enquiry Concerning Human Understanding, full text 1, 2
Hume, D. Treatise of Human Nature 1, 2, 3
Turing, A.M. Computing Machinery and Intelligence, full text 1, 2, 3,