It should be evident that Aristotle's treatment of virtues as mean states endorses the idea that we shouldsometimes have strong feelings—when such feelings are called for by our situation. Sometimes only a small degree of anger is appropriate; but at other times, circumstances call for great anger. The right amount is not some quantity between zero and the highest possible level, but rather the amount, whatever it happens to be, that is proportionate to the seriousness of the situation. Of course, Aristotle is committed to saying that anger should never reach the point at which it undermines reason; and this means that our passion should always fall short of the extreme point at which we would lose control. But it is possible to be very angry without going to this extreme, and Aristotle does not intend to deny this. (From Kraut's article on Aristotle's ethics in the Stanford encyclopedia, my emphasis.)
Because I had a conversation about it the other day, I was reminded of the familiar caricature of the angry feminist (or whatever other lefty activists you tend to hang out with): they're angry, they say mean things, they won't listen to my well reasoned apologies for oppression, and they won't laugh at my hilarious dumb blonde jokes, so they're wrong and don't have a sense of humour. Of course, the first and most important thing to point out is that feminists are nowhere near this dour -- there's plenty of empirical evidence of feminists putting forward rational arguments to defend their positions and enjoying such universal goods as jokes and fucking. Just watch a performance of The Vagina Monologues or flip through Katha Pollitt's new book.
But, secondly, there are lots of feminists who say angry, irrational things; the internecine
warfare of the feminist blogosphere, sadly, is the source of a ridiculous number of examples. And, inevitably, when the vitriol starts to fly (there's a mangled metaphor for you; maybe it's been gelatinized?), someone will start talking about civility and politeness. While well-intentioned, this only exacerbates things, because you end up with a meta-fight about the importance of anger in challenging oppression.
Ignoring his rampant sexism (Aristotle would actually say that women are emotional creatures whose highest good is not eudaimonia but making babies), how would Aristotle comment on the meta-fight? With the emphasized subordinate clause from the quotation above: It is entirely appropriate, even virtuous and praiseworthy, to be furious with injustice and oppression, but not to the point that one is unable to think and act rationally. In some situations it is unquestionably virtuous to lash out with heated rhetoric and a call-to-arms; but when, for instance, a certain blogger bans a fellow feminist until she can lay off the ad hominems, are we really in one of those situations?