It has often been said—in fact, I have said it quite emphatically myself—that it is impossible to deduce ethical conslusions from non-ethical premises. This now seems to me to be a mistake (A.N. Prior, ``The Automomy of Ethics", (1960))
Hume's Is/Ought Thesis in Logics with Alethic/Deontic Brigde Principles, Gerhard Schurz (1994)
Logic and the Autonomy of Ethics, Charles Pigden (1989)
The Automomy of Ethics - A.N. Prior in the Australiasian Journal of Philosophy, no. 38. 1960
Defining the Autonomy of Ethics - Frank Jackson in Philosophical Review, January 1974, no. 83
A Study of Philosophical Taxonomy - Lloyd Humberstone in Philosophical Studies, 1996, 83(2)