The Theory of Moral Sentiments
David Hume
The Basis of Morality
The Myth of Moral Justice
Fundamental Principles of the Metaphysic of Morals by Immanuel Kant - Delphi Classics (Illustrated)
The Genealogy of Morals by Friedrich Nietzsche - Delphi Classics (Illustrated)
An Enquiry Concerning the Principles of Morals