"In writing about Nazi Germany, Hannah Arendt addresses the question: "in what way were those few different who in all walks of life did not collaborate and refused to participate in public life, though they could not and did not rise in rebellion?" This is part of her answer:
I therefore would suggest that the nonparticipants were those whose consciences did not function in this, as it were, automatic way- as though we dispose of a set of learned or innate rules which we then apply to the particular case as it arises, so that every new experience or situation is already prejudged and we need only act out whatever we learned or possessed beforehand. Their criterion, I think, was a different one: they asked themselves to what extent they would still be able to live in peace with themselves after having committed certain deeds; and they decided that it would be better to do nothing, not because the world would then be changed for the better, but simply because only on this condition could they go on living with themselves at all. Hence, they also chose to die when they were forced to participate. To put it crudely, they refused to murder, not so much because they still held fast to the command “Thou shalt not kill,” but because they were unwilling to live together with a murderer- themselves.
The precondition for this kind of judging is not a highly developed intelligence or sophistication in moral matters, but rather the disposition to live together explicitly with oneself, to have intercourse with oneself, that is, to be engaged in that silent dialogue between me and myself which, since Socrates and Plato, we usually call thinking. This kind of thinking, though at the root of all philosophical thought, is not technical and does not concern theoretical problems. The dividing line between those who want to think and therefore have to judge by themselves, and those who do not, strikes across all social and cultural or educational differences. In this respect, the total moral collapse of respectable society during the Hitler regime may teach us that under such circumstances those who cherish values and hold fast to moral norms and standards are not reliable: we now know that moral norms and standards can be changed overnight, and that all that then will be left is the mere habit of holding fast to something. Much more reliable will be the doubters and skeptics, not because skepticism is good or doubting wholesome, but because they are used to examining things and to make up their own minds. Best of all will be those who know only one thing for certain: that whatever else happens, as long as we live we shall have to live together with ourselves.”