Perhaps the best nugget to be gleaned from this article is that we are all "stupid" at least some of the time. When we are witness to or even victims of stupdity, that is something to keep in mind.

It mostly (and accurately) equates "stupidity" with mindlessness: a failure to take other people and things into account to the extent we should have. My studies have taught me that as far as relations among human beings go, that is what injustice is.

So, it is 'stupid' to act unjustly; to act unjustly is to be 'stupid'.