I just listened to this neat conversation, which summarizes some empirical research into the question of whether thinking about moral philosophy makes you any better at behaving morally. It turns out moral philosophers are actually slightly more likely to steal library books than philosophers in other areas, and political philosophers are no more likely to vote than people in other profession.
The speakers mention that these results are surprising, since they conflict with the hope that researching moral philosophy will have morally good effects.
Now I'm pretty skeptical about moral philosophy myself, for other reasons, but here's what the moral philosophers would/could say for themselves on this score:
"The phenomenon of weakness of the will, means that there are two components to doing what's good: the epistemic component of figuring out what's morally better/required in a given case, and then the practical component of actually doing that.
Moral philosophy only pretends to address the first component. Thinking hard about weird trolley cases, and abstract moral principles helps you figure out what you ought to do in cases where this is unclear. It doesn't address the second component of acting well - working up the will power to actually do what you ought to.
In this way, moral philosophers are like scientists who study fistfights not professonal boxers. They spend a long time studying the differences between different principles that only make a difference to what one should in principle do in certain rare cases. They don't spend this time practicing up their personal ability to implement the overall art of fighting well.
For this reason, testing whether moral philosophers are more virtuous in cases where it's *obvious*/uncontroversial what's virtuous (you should return library books, you should vote) exactly fail to capture the benefits that doing moral philosophy brings. Studying moral philosophy helps society make the world better, because the moral philosophers work out what we should do in novel, or controversial cases. This doesn't mean that it makes moral philosophers themselves substantially more virtuous. For, in most of the cases where ordinary people have a chance to act badly (adultery, embezzlement, falsifying data, refusing charitable aid) the limiting factor isn't *figuring out* what the right thing to do is, but rather summoning the willpower to sacrifice individual pleasure and benefit to do whats right."