PETER SINGER

ETHICS AND INTUITIONS
(Received 25 January 2005; accepted 26 January 2005)

ABSTRACT. For millennia, philosophers have speculated about the origins of ethics. Recent research in evolutionary psychology and the neurosciences has shed light on that question. But this research also has normative significance. A standard way of arguing against a normative ethical theory is to show that in some circumstances the theory leads to judgments that are contrary to our common moral intuitions. If, however, these moral intuitions are the biological residue of our evolutionary history, it is not clear why we should regard them as having any normative force. Research in the neurosciences should therefore lead us to reconsider the role of intuitions in normative ethics.
KEY WORDS: brain imaging, David Hume, ethics, evolutionary psychology,
Henry Sidgwick, Immanuel Kant, intuitions, James Rachels, John Rawls, Jonathan
Haidt, Joshua D. Greene, neuroscience, trolley problem, utilitarianism

1. INTRODUCTION
In one of his many fine essays, Jim Rachels criticized philosophers who ‘‘shoot from the hip.’’ As he put it:
The telephone rings, and a reporter rattles off a few ‘‘facts’’ about something somebody is supposed to have done. Ethical issues are involved – something alarming is said to have taken place – and so the ‘‘ethicist’’ is asked for a comment to be included in the next day’s story, which may be the first report the public will have seen about the events in question.1

In these circumstances, Rachels noted, the reporters want a short pithy quote, preferably one that says that the events described are bad. The philosopher makes a snap judgment, and the result is

1
James Rachels, ‘‘When Philosophers Shoot from the Hip,’’ in Helga Kuhse and
Peter Singer (eds.), Bioethics: An Anthology (Oxford: Blackwell Publishers, 1999),
p. 573.

The