Mindlessly taking the first small step. Even if the first step seems small it can lead to greater things. Like in the Milgram experiment. In the begging the participants gave a small 15-volt shock. Which was a small step and turned into them using 450 volts. Evil starts out small.
Dehumanizing others. In the Stanford Prison Study, is a study were they randomly assigned prisoners and guards. The prisoners were then arrested at their homes and assigned numbers to dehumanize them. Where the guards begin coming up with ways to dehumanize the prisoners.
One thing they made them do is clean the toilets with their hands. The experiment went out of control, causing it to end in 6 days instead of 2 weeks.
Deindividuation of self. The uniforms of the military make any acts done more anonymous and promote group or mob mentality. The idea of I am just blending in, so it is okay. When we are conformed in this manner we are more violent.
Diffusion of personal responsibility. When you see someone being bullied and no one else is doing anything, you are more prone to not do anything either. The bystander effect of if others dont do something, I wont either.
Blind obedience to authority. In the late 1970s Cambodia was experiencing mass genocide. Which killed roughly 2.5 million people. Pol Pot was the leader of the group called the Khmer Rouge. The Khmer Rouge singled out anyone with an education, and ethnic or religious minorities. The Khmer Rouge kept people in make shift prisons where they brutally tortured them. An made the killing fields where they would force them to work in rice fields with barely any food and for long periods. When other countries finally got involved, the Khmer Rouge used the reason they didnt know any better they were just doing what Pol Pot told them. If there are a leader people are way more prone to follow.
Uncritical conformity to group norms. The torture of Iraqi prisoners by U.S. soldiers at Abu Ghraib is a prime example. The soldiers dehumanization of the prisoners was so common that they took more than 1,000 cell phone photos. This practice wasnt challenged for months because it was normal in this group.
Passive tolerance of evil through inaction or indifference. The thought or mentality that what someone is doing isnt better or worse then others so its okay. Or well they arent dead so its not that big of a deal. Or the thought that no one really cares greatly so if mistreatment happens its okay. This was I big mentality in State asylums during the late 1800 and mid 1900.