Moral integrity range
About
The moral integrity range is the range of all possible levels of moral integrity. At one end of the scale are those who will do what is best for everyone (in their best judgment) regardless of personal consequences (altruism); at the other end are those who will act solely for their own benefit no matter how terrible the consequences to others (selfishness).
Most people, of course, fall somewhere in between these two extremes; there is some anecdotal evidence to suggest that humanity in general falls into something like a bell curve, with the vast majority of people deciding whether to be selfish or altruistic depending more on circumstances (including degree of personal benefit and the amount and nature of social pressure they are experiencing) than on their own moral compass.
This is also known as the 10-80-10 rule:
In pretty much any society, 10% of people (give or take about 5%) are going to be heroes, no matter what: people with strong moral compasses, unwilling to be swayed from that. Another 10% (give or take 5%) are going to be villains, no matter what: they will engage in villainy and violence for the sheer fun of it. But the large majority of the population — the 80% in the middle — is neither. Instead, they will set their norms of what is acceptable by watching people around them.