Very nice and also a very timely subject. I've also put some thought into this and seems to me that the evil that we see in the world has two fundamental sources. The first are people who are just truly evil: they enjoy hurting others. I suspect that there are not very many of these. The second is far more prevalent and much harder to eliminate: evil that is justified in the name of a higher good. If you look at accurate explanations for the subject behavior in Milgram's Obedience under Authority experiments, he showed that normal people were willing to inflict pain and even go as far as killing someone only when they were doing it for a higher purpose. They knew what they were doing was wrong and were quite disturbed by it, yet they did it anyway, for the greater good. (If you don't know these experiments, no one was actually hurt, because the person the subject thought they were electrocuting was an actor.)

While truly evil people may hide, those doing evil for a higher good actually do everything in the open, because they truly believe it is a higher good. There are exceptions, of course. I suspect that Trump is one who is truly evil as you can see from his twitter feed and all of his past misdeeds and statements flaunting them (e.g., about grabbing women). But most are not truly evil, but are instead justifying evil by pointing to a higher good. Faith-based reasoning is ideal for this, whether it is faith in a religion or some other ideology, such as trickle down economics or capitalism. Note that much of the evil in governments and businesses today are of the higher good kind. US politicians justified torture to prevent another 911 type of attack--they even got psychologists to go along with it! The US has a massive gun violence problem, yet the NRA justifies weak gun laws by citing it as a right, even though the founding fathers never imagined semi (or fully) automatic weapons capable of killing and maiming dozens in a few minutes. If you look at all of the scams in businesses, it almost always comes down to continued bending of the rules to meet mandates handed down by higher up leaders who never learned the dangers of managing by outcomes. When lower level people are being forced to make impossible stretch goals or else lose their job (or part of their pay), many will game the system.

Then we get to religion, which is perhaps the king of using higher good as an excuse for evil. Almost every religion has and still continues to commit evil in the name of their beliefs. Since those beliefs have no foundation in evidence, but are not to be questioned as they are ____-given (insert your favorite deity here), it is easy to use them to justify great harm. Just a few days ago, Congressman Steve King, defending a bill to ban abortion, including pregnancies brought through rape and incest said “What if we went back through all the family trees and just pulled out anyone who was a product of rape or incest? Would there be any population of the world left if we did that?” He later said that he didn't say that, but in fact it is on tape. He also still is supporting the bill. As a personal aside, if such a thing happens, I will likely look to move out of the US, since I have three daughters. This is getting to be like the handsmaid tale.

I suggest that everyone interested in these issues, read Zeynep Tufekci's article on why the final season of GoT is so bad (https://blogs.scientificamerican.com/observations/the-real-reason-fans-hate-the-last-season-of-game-of-thrones/). She points out that Martin's story was sociological--showing how people's actions are shaped by society, which often results in people being a mix of good and evil. However, once hollywood ran out of his books, the writers changed the story to a typical psychological tale about individuals, instead of society. This is why the last two seasons felt as if characters seemed so out of character--the story was no longer sociologically driven.

Next, watch the series The Wire (Netflix or HBO). This is a 5 season series telling a sociological story about police, gangs, politics, unions, and school system in Baltimore. The corruption and the positive behaviors (often in the same character) are driving by the situations they find themselves in. The most moral person in the story is a homeless drug addict. Nearly everyone else justifies bad behavior for one or more higher goods.