Or: always focus on the intent. People do things for different reasons, but you should only judge them based on the intent.
For example, all lives matter, sounds good, but what is the intent behind that? Is it really to signal that all lives matter?
For example, all lives matter, sounds good, but what is the intent behind that? Is it really to signal that all lives matter?
Alternatively we can look at the effects of an action. To use your example, when someone says “all lives matter” it, among other things, alienates black people. IMO makes it a lot more clear cut.