Epistemic status: I feel confident in this. I find it useful. But its mostly based on introspection.
First a story.
Once, I was having a conversation with a friend about not wanting to draw diagrams to help me strategize because it didn’t feel like it helped. As we talked, I fretted to myself about sharing a vulnerable point: that when I write things down or make diagrams for myself, I feel a strong urge towards making my diagram as formal and complete as I can. I often feel bad about not being able to make my diagram more formal, and give up on making it. I knew abstractly that this urge was harmful, and in the conversation it was obvious I was wasting time on it, so sharing it would open me up to ridicule and judgement. But I felt just barely safe enough, so I shared it anyway.
The first thing my friend said was an exasperated “John, you’re going to have to stop doing things like that.” Which hurt a lot for a split second.
But I had been training to respond with anger sometimes, and I was able to respond by shoving them in the shoulder and saying “I fucking know that. Can you listen to me?”. My friend apologized, saying they had been quick jump to conclusions, and we continued the conversation productively.
This whole exchange took probably 30 seconds.
My expression of anger let me protect myself from my friend attributing an unsophisticated perspective to me and ending up with a poor opinion of me.
The most interesting thing is that I think that my ability to be angry with the made it more possible for me to share this vulnerable point in the first place. If my friend threatened to think badly of me, I had a way to respond. I would not have shared it without that possibility.
What is anger for?
I think this question and several like it are extremely useful. What information does it carry? What is it trying to get me to do? And given that, what is the right way to respond to it?
My current theory is that you feel angry when one part of you judges that one of your allies is undervaluing your welfare in some way and that it’s correctable.
This makes sense of who you feel anger towards. You only feel anger towards people who you think could and should take your welfare into account. You’re much more likely to feel angry towards your friends than strangers. And when you do feel angry towards strangers it’s usually accompanied by a feeling that they’re ‘supposed’ to take your welfare into account. You won’t feel anger towards invading aliens (though maybe aggression), but you will feel anger towards your roommate leaving crap on the floor.
On this theory, the proper response to anger is to show the person you’re angry at that you see that they’re undervaluing your welfare and that you’re willing to punish them to make them stop. This is good for the relationship; the other person will be less tempted to undervalue your welfare if they know you will often catch them.
I have had an extremely difficult time expressing anger. It seemed to be cruel to be angry at people. But now I think it is useful and healthy, especially in small, short bursts (the most information dense).
Anger is there for a reason: it’s telling you about the world. And understanding what anger is trying to communicate can help you respond better to it.
Edit (09/25/2016): All emotions are there for a reason. See also this model of shame.
Many thanks to Katja Grace. I developed this theory through discussions with her and could not have done it without her.