A part which seems missing in the discourse -- probably because of politeness or strategy -- is that there are more than two sides, and that people on your side don't necessarily share all your values. When someone tells you: "Harry, look how rational I am; now do the rational thing and follow me in my quest to maximize my utility function!" it may be appropriate to respond: "Professor Quirrell, I have no doubts about your superb rationalist skills, but I'd rather use my own strategy to maximize my utility function." Your partner doesn't have to be literally Voldemort; mere corrupted hardware will do the job.

On the battlefield, some people share the common goal, and some people just enjoy fighting. Attacking the enemy makes both of them happy, but not for the same reasons. The latter will always advocate violence as the best strategy for reaching the goal. (The same thing happens on the other side, too.)

And an imporant part of the civilizing process Scott described is recognizing that both your side and the other side are in a constant risk of being hijacked by people who derive their benefits from fighting itself, and who may actually be more similar to their counterparts than they are to you. And that miraculous behavior which shouldn't happen and seems like a losing strategy, is actually the civilized people from the both sides half-knowingly forging a fragile treaty with each other against their militant allies and leaders.

Which feels like a treason... because it is! It is recognizing that there is some important value other than the official axis of the conflict, and that this value should be preserved, sometimes even at cost of some losses in the battlefield! -- This is what it means to have more than one value in your utility function. If you are not willing to sacrifice even epsilon of one value to a huge amount of the other value, then the other value simply does not exist in your utility function.

So, officially there is a battle between X and Y, and secretly there is a battle between X1 and X2 (and Y1 and Y2 on the other side). And people from X1 and X2 keep rationalizing about why their approach is the best strategy for the true victory of X against Y (and vice versa on the other side).

Civilization is a tacit conspiracy of decent people against psychopaths and otherwise defective or corrupted people. Whenever we try to make it explicit, it's too easy for someone to come and start yelling that X is the side of all decent people, and Y is the side of psychopaths, and this is why we from X have to fight dirty, silence the heretics in our own ranks and then crush the opponents. So we stay quiet amidst the yelling, and then we ignore it and secretly do the right thing; hoping that the part of conspiracy on the other side is still alive and ready to reciprocate. Sometimes it works, sometimes it doesn't; but on average we seem to be winning. And I wouldn't trade it for a "rationalist" pat on shoulder from someone I don't trust.