Moral sense theory (also known as moral sentimentalism) is a theory in moral epistemology and meta-ethics concerning the discovery of moral truths. Moral sense theory typically holds that distinctions between morality and immorality are discovered by emotional responses to experience. Some take it to be primarily a view about the nature of moral facts or moral beliefs (a primarily metaphysical view)—this form of the view more often goes by the name "sentimentalism". Others take the view to be primarily about the nature of justifying moral beliefs (a primarily epistemological view)—this form of the view more often goes by the name "moral sense theory". However, some theorists take the view to be one which claims that both moral facts and how one comes to be justified in believing them are necessarily bound up with human emotions.
Popular historical advocates of some version of the moral sense theory or sentimentalism include the 3rd Earl of Shaftesbury (1671–1713), Francis Hutcheson (1694–1746), David Hume (1711–1776), and Adam Smith (1723–1790). Some contemporary advocates include Michael Slote, Justin D'Arms, Daniel Jacobson, Jesse Prinz, Jonathan Haidt, and perhaps John McDowell. Simon Blackburn and Allan Gibbard endorse a non-cognitivist form of sentimentalism.
Intuition versus moral sense
Some use the term "ethical intuitionism" in moral philosophy to refer to the general position that we have some non-inferential moral knowledge (that is, basic moral knowledge that is not inferred from or based on any proposition). On this definition, moral sense theory is a form of ethical intuitionism.
However, it is important to distinguish between empiricist versus rationalist models of this. One may thus distinguish between rationalist ethical intuitionism for the rationalist version and "moral sense theory" for the empiricist version. (This will be the use of the terms here. However, the terminology is not ultimately important, so long as one keeps in mind the relevant differences between these two models of non-inferential moral knowledge.)
History
The first prominent moral sense theory (especially using the term "sense") is found in Mencius (372–289 BCE). The eponymous text deals with an innate moral sense possessed by all human beings. All orthodox interpretations of Confucianism accept this view, several unorthodox groups make a point of refuting it (see: Xunzi). This line of thinking reached its most extreme iteration in xinxue, a form of Neo-Confucianism associated with the Ming Dynasty and Wang Yangming.
In the West, the first prominent moral sense theory is found in Anthony Ashley-Cooper, 3rd Earl of Shaftesbury (1671–1713). His major work espousing a form of moral sense theory is An Inquiry Concerning Virtue, or Merit (first published in an unauthorized edition in 1699).
Subsequently, Francis Hutcheson (1694–1746) developed a version of moral sense theory. The chief statements of his theory occur in An Inquiry Concerning the Original of Our Ideas of Virtue or Moral Good (1725; Treatise II of An Inquiry Into the Original of Our Ideas of Beauty and Virtue) and An Essay On the Nature and Conduct of the Passions and Affections, With Illustrations Upon the Moral Sense (1728).