Here is my very late reply to Jim on skepticism about moral character.
The short answer: No, in all my moderately extensive reading on this subject, I have not found any “studies that actually involve the observation of a person’s behavior across a wide range of relevant circumstances,” as opposed to studies which deal with only a kind of “snapshot” of a person’s behavior.
The longer answer: I think only the virtue ethicists, and not the situationists, think such a study would vindicate the idea of robust character traits. Here’s why (very generally speaking, from my reasonably informed point of view on the subject).
The virtue ethicists (like Aristotle) have accounts on which it could be the case that a person does have a rather robust character trait, but that in extreme situations this trait is, in a sense, prone to being overriden (e.g., in Milgram scenarios containing an authoritative experimenter, or whatever). The existence of compassion in a person who acts cruelly in the snapshot captured by the Milgram experiment could be vindicated by a long-term study of some kind showing compassion manifested most of the time in compassion-relevant situations.
It seems to me that the situationists have a different interpretation of the force of the Milgram experiments and similar evidence. At least some of them appear to think that, if character traits have any real role in determining behavior at all (as virtue ethicists hold), that they would prevent at least the totally egregious moral transgressions witnessed in the Milgram and Stanford Prison experiments. And, if the data is indeed sufficient for disproving the kinds of traits that virtue ethicists postulate, then it’s understandable that the situationists would have limited interest in other patterns of behavior. (John Doris does think that there are narrow, as opposed to robust, character traits, such as academic honesty as distinct from personal relationship honesty. These could probably be verified by empirical observation. Also, notice that the situationists’ explanation here – if it is at all how I explain it – would not pertain to the dime in the phone booth-type experiments, which do not involve egregious moral transgressions).
As for this part of Jim’s comment:
Suppose that everyone who really knows Fred considers him to be a reliably compassionate person. But two psychologists who were hiding behind a ficus tree, watching as Fred walked past a poor soul who’d just dropped a bunch of papers, insist that he clearly could not have so robust a character trait. Surely, the people who really know Fred are in a better position than any psychologist hiding behind a ficus tree (or worse, any philosopher sitting in an armchair) to judge the robustness of Fred’s putative traits, right?
What the situationists tend to say about this is the following: Because people who know each other well see each other in the same types of situations over and over, it is unsurprising that Fred’s friends have formed apparently accurate conceptions of what his moral character is like. But when people who work with Fred see him at home, or people who go to school with Fred see him in a restaurant, it is rather likely that he will act in a way that is incompatible with the traits they thought Fred had (and this is even more likely to be the case when Fred is put in an extreme situation, such as a war or an emergency). This evidence is compatible with both the interpretation that there are no character traits (Gilbert Harman) and that there are narrowly defined and not robust character traits (John Doris).
In my opinion, it is not very useful at that point to debate whether people have “character traits” at all or not, because everyone seems to have a different definition for what a “character trait” is. Instead, we should try to figure out what kind of virtue ethics, if any, remains consistent with the empirical evidence, and work backwards to what the empirically adequate notion of virtues or character traits might be. See Maria Merritt, Virtue Ethics and Situationist Personality Psychology for a good starting point. I am still thinking it over myself.