The well-known theory of evil's banality, enunciated in the subtitle of the book Eichmann in Jerusalem, takes Hannah Arendt to orientate her research towards the "activities of the sipirit", which are the thought, the will, and the judgement. From her point of view, what is characteristic to the evil perpetrated by the criminal Nazis is the absence of thought and judgement, their incapacity to reflect on what is going to be done, or what has been done, and the incapacity to judge it applying the common sense of morality. From this hypothesis, Arendt begins the analysis of the thought and judgement faculties, with the aim of establishing the fundamental moments and conditions needed for the formation of moral conscience.
Thinking is a dialogue with ourselves, putting at the same time some distance from reality, with the intention of finding some sense. In this internal search, the individual, a community being by definition, can also collect the opinion of others. She becomes a spectator of "wide mentality" that judges a certain reality or situation. Convinced about the fact that moral judgements should not go from the general principles to particular cases, but the other way around, from examples to the statements. Arendt feels more affinity with the Kantian analysis about the judgement of taste, than with the categorical imperative. She uses the appreciation of a work of art, initially subjective, as a model for moral judgement. A judgement not attempting to be a universal abstraction, but to extend intersubjectively and gain the approval of as many opinions as possible.
The aim of moral judgement is to rebuild a sensus communis, or common sense, essential for the political life. Such sense is acquired or recovered through a double movement with which the individual seeks the agreement of other, but even more importantly, his own agreement. It is this integrity with ourselves, the rejection of everything that makes us resign from authenticity, what makes a person decide at the same time how and with who to live. This way, the common sense or the moral sense is for Hannah Arendt the personal effort to avoid the the trend of ceasing thought and judgement, and thus, the assumption of any kind of responsibility.
As a consequence of this anti-metaphysic pulse and her theory that philosophy is thinking without using supports, Arendt is not proposing the fundaments of moral, but a phenomenology of moral discernment to only establish the conditions under which this can and should happen. It is not about reaching a truth about moral, but above all, avoiding uncritical conformity with what is given. Moral integrity is, on top of everything, the fight against indifference.