Below is a draft of a section of the Stanford Encyclopedia of Philosophy entry on “Experimental Moral Philosophy.” Comments welcome. Apologies for typos and missing citations.
Which tasks are appropriate to experimental ethics? The answer to this question depends on which aspects of ethics are under investigation. Experimentalists investigate moral intuition, moral judgments, moral emotions, and moral behaviors, among other things. The most thoroughly investigated is moral judgment, which we discuss now.
One project for the experimental ethics of moral judgment, associated with Stephen Stich and Jonathan Weinberg, is to determine the extent to which philosophical intuitions are shared by both philosophers and ordinary people. (The distinction between moral intuitions and moral judgments is fraught, but for the sake of this discussion, we’ll treat moral intuitions as moral seemings and moral judgments as considered moral beliefs.) As Stich, Weinberg, and their fellow travelers are fond of pointing out, many philosophers appeal to intuitions as evidence or use their content as premises in arguments. They often say such things as, “as everyone would agree, p,” “the common man thinks that p,” or simply, “intuitively, p.” But would everyone agree that p? Does the common man think that p? Is p genuinely intuitive? These are empirical questions, and if the early results documented by experimental philosophers are replicated, the answer would often seem to be negative. This raises the question of how much work the adverb ‘intuitively’ is meant to do when it comes out of a philosopher’s mouth. If it’s just something she says to clear her throat before she makes an assertion, then the fact that intuitions exhibit a great degree of variance matters little. If, on the other hand, the claim “intuitively p” is meant to be evidence for p, the philosophers who make such claims should tread carefully.
Furthermore, the factors that predict disagreement about supposedly intuitive philosophical claims are often non-evidential. Women find p intuitive, whereas men find ~p intuitive (Buckwalter & Stich forthcoming). Westerners mostly agree that q, but East Asians tend to think ~q (Machery, Mallon, Nichols, & Stich 2004). People find r plausible if they’re asked about s first, but not otherwise (Nadelhoffer & Feltz 2008; Sinnott-Armstrong 2008; Sinnott-Armstrong, Mallon, McCoy, & Hull 2008). This leads to the second use of experimental evidence: arguing for the (un)reliability of moral intuitions, and, to the extent that moral judgments are a function of moral intuitions, those as well. Walter Sinnott-Armstrong (2008) and Eric Schwitzgebel and Fiery Cushman (2012) have recently followed this train of thought, arguing that moral intuitions are subject to normatively irrelevant situational influences (e.g., order effects), while Feltz & Cokely (2009) and Knobe (2011) have demonstrated correlations between moral intuitions and (presumably) normatively irrelevant individual differences (e.g., extroversion). Such results, if they can be replicated and explained, may warrant skepticism about moral intuition, or at least about some classes of intuitions or intuiters.
Other philosophers are more sanguine about the upshot of experimental ethics. Joshua Knobe, among others, attempts to use experimental investigations of the determinants of moral judgments to identify the contours of philosophically interesting concepts and the mechanisms or processes that underlie moral judgment. He has famously argued for the pervasive influence of moral considerations throughout folk psychological concepts (2009, 2010; see also Pettit & Knobe 2009), claiming, among other things, that the concept of an intentional action is sensitive to the moral valence of the consequences of that action (2003, 2004b, 2006). Others, such as Joshua Greene and his colleagues (2001, 2004, 2008), argue for dual-systems approaches to moral judgment. On their view, a slower, more deliberative, system tends to issue in utilitarian judgments, whereas a quicker, more automatic system tends to produce Kantian judgments. Which system is engaged by a given moral reasoning task is determined in part by personal style and in part by situational factors.
A related approach favored by Chandra Sripada (2011) aims to identify the features to which philosophically important intuitions are sensitive. Sripada thinks that the proper role of experimental ethics is not to identify the mechanisms underlying moral intuitions – such knowledge, it is claimed, contributes little of relevance to philosophical theorizing. It is rather to investigate, on a case by case basis, the features to which people are responding when they have such intuitions. On this view, people (philosophers included) can readily identify whether they have a given intuition, but not why they have it. An example: “manipulation cases” have been thought to undermine compatibilist notions of free will. In such a case, an unwitting person is surreptitiously manipulated into having and reflectively endorsing a motivation to j. Critics of compatibilism say that such a case satisfies compatibilist criteria for free will, and yet, intuitively, the actor is not free. Sripada showed, however, through both mediation analysis and structural equation modeling, that to the extent that people feel the manipulee not to be free, they do so because they judge him in fact not to satisfy the compatibilist criteria. Thus, by determining which aspects of the case philosophical intuitions are responding to, it may be possible to resolve otherwise intractable questions of interpretation.
 See Doris & Stich (2006) and Stich & Weinberg (2001).
 Though for incisive criticisms of this claim, see Banerjee, Huebner, & Hauser (2010), Sytsma & Livengood (2011), and Lam (2010).
 Fiery Cushman and Liane Young (2009, 2011) have developed an alternative dual-process model for moral (and non-moral reasoning), as has Daniel Kahneman (2011).