Hannah Arendt used Eichmann as a lens by which to understand better the conditions that made totalitarianism possible. She attended his trial in Israel. She was forcefully struck by his use of banalities and clichés to explain and justify his actions and policies in the Nazi government.
Specifically, Adolf Eichmann was for her a perfect example of an otherwise intelligent human being who did not think. He calculated, he reckoned, but he gave no indication that he was capable of reflection, critical or otherwise, upon his own actions and words. For the textually curious, she gave the most extended treatment of Eichmann in Eichmann in Jerusalem, but the best explanation of why Eichmann matters is to be found in her introduction to The Life of the Mind.
For all of her insight and eloquence, Arendt never once provides an account of how someone might have become thoughtless like Eichmann. This should strike anyone as a troubling paradox: how can a putative absence, in this case, of thought and reflection, be the result of the exercise of reason and thought?
Two value judgments suffice to explain Eichmann's thoughtlessness. The first is that the absence of any specific intent to do wrong, evil, or hurt is desirable. The exact term is unimportant. The consequence of this high valuation of an absence of bad intent is the temptation to conclude that because one is unable to form an intent to bad things one is therefore "good." Why? Because one has done nothing wrong and cannot even conceive of doing something morally wrong.
Speaking ironically, this can be attributed to an over valuation of having a clear conscience. One gets in the habit of not thinking about one's bad and socially unacceptable impulses. This all ends with an inability to consider that someone else might think differently about one's actions, words, and justifications.
The second is more difficult to phrase so succinctly or maybe it's a consequence of the first judgment. This second is an absence. More specifically, it is an absence of courage. Or an absence of confidence in oneself. Or an unwillingness to recognize risk in human affairs as inevitable. Or its a lack of love: there's nothing in this world that merits defense and protection at the cost of one's own safety. But there is a great deal to be fearful of losing.
Taken together, these two judgments result in a faith in necessity: one must do what one must do in order to survive, get ahead, or some other self-serving euphemism. BUT one's are judged and evaluated not how it affects other people, but according to what one intended.
These reflections lead to an unexpected insight: living with and around other people implies an obligation and expectation of considering and taking into account other people: what they will likely think and the effects they will probably suffer.
This is consideration of others is not determinative of what one should or should not do. This consideration of others requires the recognition that how one would like one's own actions to be judged is just one possible way of judging among others.
I suspect part of the belief in the Last Judgment was a recognition that the those intentions accompanying one's life and deeds were to be judged as well and were by no means decisive. One's words, deeds, life, and intentions would be judged by another.
The above can perhaps be summed up in that Eichmann and the little Eichmann's that surround us wish for their actions to be judged not by how their acts, deeds, and words affect the people around them, but they believe that they should be judged and evaluate their own acts, deeds, and words by the ends to which they seek to achieve.