Below is a draft of the section of the Stanford Encyclopedia of Philosophy article on “Experimental Moral Philosophy” devoted to virtue ethics and skepticism about character. As always, comments and criticisms are most welcome. And again my apologies for typos and missing citations.
A virtue is a complex disposition comprising sub-dispositions to notice, construe, think, desire, and act in characteristic ways. To be generous, for instance, is (among other things) to be disposed to notice occasions for giving, to construe ambiguous social cues charitably, to want to give people things they need or would enjoy, to deliberate well about what would in fact be appreciated, and to act on the basis of such deliberation. Manifestations of such a disposition are observable and hence ripe for empirical investigation. Virtue ethicists of the last several decades have tended, furthermore, to be optimistic about the distribution of virtue in the population. Alasdair MacIntyre claims, for example, that “without allusion to the place that justice and injustice, courage and cowardice play in human life very little will be genuinely explicable” (1984, p. 199; see also Annas 2011, pp. 8-10).
The philosophical situationists John Doris (1998, 2002) and Gilbert Harman (1999, 2000, 2003) were the first to mount an empirical challenge to the virtue ethical conception of character, arguing that social psychology of the last century has shown that most people are surprisingly susceptible to seemingly trivial and normatively irrelevant situational influences, such as mood elevators (Isen, Clark, & Schwartz 1976; Isen, Shalker, Clark, & Karp 1978; Isen 1987), mood depressors (Apsler 1975; Carlsmith & Gross 1968; Regan 1971; Weyant 1978), presence of bystanders (Latané & Darley 1968, 1970; Latané & Rodin 1969; Latané & Nida 1981; Schwartz & Gottlieb 1991), ambient sounds (Matthews & Cannon 1975; Boles & Haywood 1978; Donnerstein & Wilson 1976), ambient smells (Baron 1997; Baron & Thomley 1994), and ambient light levels (Zhong, Bohns, & Gino 2010). Individual difference variables tend to explain less than 10% of the variance in people’s behavior (Mischel 1968) – though, as Funder & Ozer (1983) point out, situational factors typically explain less than 16%.
Philosophical situationists argue on the basis of such evidence that the structure of most people’s dispositions does not match the structure of virtues (or vices). According to Doris (2002), the best explanation of this lack of cross-situational consistency is that the great majority of people have local, rather than global, traits: they are not honest, courageous, or greedy, but they may be honest-while-in-a-good-mood, courageous-while-sailing-in-rough-weather-with-friends, and greedy-unless-watched-by-fellow-parishioners. In contrast, Christian Miller (2013a, 2013b) thinks the evidence is best explained by a theory of mixed global traits, such as the disposition to (among other things) help because it improves one’s mood. Such traits are global, in the sense that they explain and predict behavior across situations (someone with such a disposition will, other things being equal, typically help so long as it will maintain her mood), but normatively mixed, in the sense that they are neither virtues nor vices. Mark Alfano (2013) goes in a third direction, arguing that virtue and vice attributions tend to function as self-fulfilling prophecies. People tend to act in accordance with the traits that are attributed to them, whether the traits are minor virtues such as tidiness (Miller, Brickman, & Bolen 1975) and ecology-mindedness (Cornelissen et al. 2006, 2007), major virtues such as charity (Jensen & Moore 1977), cooperativeness (Grusec, Kuczynski, Simutis & Rushton 1978), and generosity (Grusec & Redler 1980), or vices such as cutthroat competitiveness (Grusec, Kuczynski, Simutis & Rushton 1978). On Alfano’s view, when people act in accordance with a virtue, they often do so not because they have the trait in question, but because they think they do or because they know that other people think they do. He calls such simulations of moral character factitious virtues, and even goes so far as to suggest that the notion of a virtue should be revised to include reflexive and social expectations.
It might seem that this criticism misses its mark. After all, virtue ethicists needn’t (and typically don’t) commit themselves to the claim that almost everyone is virtuous. Instead, they usually argue that virtue is the normative goal of moral development, and that people may fail to reach that goal in various ways. When Doris, Harman, Miller, or Alfano argues from the fact that most people’s dispositions are not virtues to a rejection of orthodox virtue ethics, then, he might be thought to be committing a non sequitur. But empirically-minded critics of virtue ethics do not stop there. They all have positive views about what sorts of dispositions people have instead of virtues.  These dispositions are alleged to be so structurally dissimilar from virtues (as traditionally understood) that it’s psychologically unrealistic to treat virtue as a regulative ideal. What matters, then, is the width of the gap between the descriptive and the normative, between the (structure of the) dispositions most people have and the (structure of the) dispositions that count as virtues.
Three leading defenses against this criticism have been offered. Some virtue ethicists (Badhwar 2009, Kupperman 2009) have conceded that virtue is extremely rare, but argued that it may still be a useful regulative ideal. Others (Hurka 2006, Merritt 2000) have attempted to weaken the concept of virtue in such a way as to enable more people, or at least more behaviors, to count as virtuous. Still others (Kamtekar 2004, Russell 2009, Snow 2010, Sreenivasan 2002) have challenged the situationist evidence or its interpretation. While it remains unclear whether these defenses succeed, grappling with the situationist challenge has led both defenders and challengers of virtue ethics to develop more nuanced and empirically informed views.
 Owen Flanagan (1991) considered some of the same evidence before Doris and Harman, but he was reluctant to draw the pessimistic conclusions they did about virtue ethics.
 Merritt (2000) was the first to suggest that the situationist critique could be handled by offloading some of the responsibility for virtue onto the social environment.
 Despite what some of their less-than-charitable readers (e.g., Flanagan 2009, p. 55) say.
 One might hope that philosophical reflection on ethics would promote moral behavior. Eric Schwitzgebel has recently begun to investigate whether professional ethicists behave more morally than their non-ethicist philosophical peers, and has found that, on most measures, the two groups are indistinguishable (Schwitzgebel 2009; Schwitzgebel & Rust 2010; Schwitzgebel et al. 2011).