What is it about certain situations that makes anger, hate or rage morally justified (beyond merely being excusable)?

Anger is normal, but it is important to take responsibility for the effects of one's anger. Anger or rage can never justify actions that inflict harm on others. Why? Well, because we are not terribly aware of what triggers such destructive power, but often the real target is not the person or object we are responding to. Take, for example, road rage. Some persons blast their horns and flip persons off - all out of anger that is often misdirected. That's an easy case, but think how anger at a spouse - that may be morally justified - often gets directed at the family dog, or worse, the children. There is little universality about anger/rage as a human feeling - and yet what triggers you may not trigger me. This suggests to me that our moral outrage tells us more about ourselves than about the world and objective moral evils in it. I am willing to grant exceptions such as the holocaust, but the need to invoke Nazi's is always a sign of a weak argument. Professor Leaman is correct of course:...

In scenarios where the metaphorical glass is either half-full or half-empty, so to speak, are there any compelling rational reasons to come down on one side or the other? Or is a person's optimism or pessimism just a character trait independent of rational thought?

Thank you Andrew, for this thoughtful response. I have been wanting to respond with notions of false dichotomies and the like, but yours is far more probing and engaging. In my thought world, however, when someone asks me if the glass is half-empty or half-full (as my academic dean did once!) I simply say it is neither - it is time for a refill! In Vino Veritas, and cheers, bjm