The whole point is to understand the context and look for solutions. Not just dismiss people you don’t like or don’t want to deal with by labeling them as stupid or lazy.
If you’ve exhausted the other options or ways to approach the problem, perhaps stupid is the explanation.
I like the variations that take it one step further, "Don't attribute to stupidity that which is adequately explained by ignorance", and "Don't attribute to ignorance that which is adequately explained by bad luck."
I've been bitten quite a few time making hasty harsh judgements because I was missing a piece of the puzzle
Having to watch the consequences of that, that person was not doing something reasonable from different point of view. It was not about axioms. It was harming everyone including that manager. (That the manager got or kept position is indictment of our company. I am fully aware.)
The sad truth is, we cant really see other people behaviour-wise. Aliens could be walking in our midst and we couldn't perceive them.
And sometimes I just want to dismiss them.