More than 50 years after its publication, Hannah Arendt’s “Eichmann in Jerusalem” remains enduringly controversial, racking up a long list of critics who continue to pick apart her depiction of the Nazi war criminal Adolf Eichmann as an exemplar of “the banality of evil,” a bloodless, nearly mindless bureaucrat who “never realized what he was doing.”

Bettina Stangneth, the author of “Eichmann Before Jerusalem: The Unexamined Life of a Mass Murderer,” published in an English translation this week by Alfred A. Knopf, didn’t aim to join those critics. An independent philosopher based in Hamburg, she was interested in the nature of lies, and set out around 2000 to write a study of Eichmann, the Third Reich’s head of Jewish affairs, who was tried in Israel in 1961, in light of material that has emerged in recent decades.

Then, while reading through the voluminous memoirs and other testimony Eichmann produced while in hiding in Argentina after the war, Ms. Stangneth came across a long note he wrote, dismissing the moral philosophy of Immanuel Kant, that flew in the face of Arendt’s notion of Eichmann’s “inability to think.”

“I sat at my desk for three days, thinking about it,” Ms. Stangneth said in a telephone interview from her home. “I was totally shocked. I could not believe this man was able to write something like this.”