Walter Sinnott-Armstrong (born 1955) is an American philosopher specializing in ethics, epistemology, neuroethics, the philosophy of law, and the philosophy of cognitive science.
[1] He earned his Ph.D. from Yale University in 1982 under the supervision of Robert Fogelin and Ruth Barcan Marcus, and taught for many years at Dartmouth College, before moving to Duke in 2010.
He strongly disagrees with several core ideas: that atheists are immoral people; that any society will become like Lord of the Flies if it becomes too secular; that without morality being laid out in front of us, like a commandment, we have no reason to be moral; that absolute moral standards require the existence of a God.
Sinnott-Armstrong is a proponent of Contrastivism, the idea that all claims of reasons are relative to contrast classes.
[4] He says that "[the contrastivist] approach applies to explanation (reasons why things happen), moral philosophy (reasons for action), and epistemology (reasons for belief), and it illuminates moral dilemmas, free will, and the grue paradox".