Not every bit of anger is a problem to be solved. Two people squaring up over something that matters, or a mother going hard at whatever threatens her child, is anger doing exactly what it is for.

What the research says

In a randomised trial of skills training for people with borderline personality disorder, part of what the treatment did was move people away from destructive and bottled up anger and towards assertive anger, meaning anger that states a need. The goal there was not the absence of anger but a better form of it. It is one trial in one clinical group, so read it as a direction of travel rather than a general rule.

Strength of evidence: one line of research. A single study, or a theoretical account.