To say something or someone is “Good” or “Evil” is an expression of subjective personal opinion. It’s qualitative and not quantifiable, but we all do it. And we all respond when others do it. I might argue that Sir Tony Blair is a good man, and someone will scream “Iraq” at me. I might argue that Ghislaine Maxwell is an evil woman and someone will say that she knew her at Oxford and that she had many friends.
I think that we often use judgment to explore our own beliefs and prejudices. Arguably Desmond Tutu had a way of bringing out the best in us – our good side which may have been buried. At the other end of the spectrum there are people, some in office, who bring out the worst in us by appealing to our darker side. Most of us have one.
Religions muddy the water. Often hypocritically. I know of few greater evils than judicial executions – but there was usually a priest near the scaffold. The Crusades were carried out by self-appointed “good” Christians to combat “evil” Muslims. The resonance from that nonsense remains with us today.
Biographies at their best are not simplistically judgmental but it is hard if not impossible to avoid the Good/Evil debate in writing them. Truth has many faces and even supposed “facts” are sometimes obscure and always open to interpretation. Look at the debate about whether the Great War was a “just war” – that’s as binary as history can be. The seeking of definitive proof about something so subjective is a fool’s errand.