Talk about people who aren’t there like they might walk in. They might.

Imagining the door opening forces you to say the thing in a form you could defend to the person’s face, which is a surprisingly good filter for whether it was fair. Rooms are smaller than they look, and the friend of the friend is always in them somewhere. What survives that test is usually true and rarely cruel.

Try it in the next conversation that drifts toward somebody absent: say only what you would say with them standing behind you. If something needs saying and cannot pass that test, it probably needs saying to them.