"[I, Eichmann,] may have been wrong all down the line, but one thing is beyond dispute: the man [Hitler] was able to work his way up from lance corporal in the German Army to Führer of a people of almost eighty million. . . . His success alone proved to me that I should subordinate myself to this man."
Of course, Eichmann essentially stated the key motivation underlying the Sith philosophy. Like Eichmann and Nazism more broadly, the Sith believed that the strongest should rule. According to the Darth Bane novels, Darth Bane believed the Sith should allow "survival of the fittest" to determine leadership within the Sith. The Master would be the one who proves him or herself the strongest, while he would take an apprentice.
Nazism and Sithism both share respect for power as an ends, not a means. For the Sith and Nazis, success determines worth and that success often involves monopolizing power for oneself. Neither philosophy leaves much room for the likes of Mother Theresa or other individuals who use their skills on behalf of others. Nor, does it seem, would the Nazis and Sith respect Cincinnatus, the roman general who famously laid down the powers of dictator after he had repelled a foreign invasion. Eichmann's quote is particularly telling as he admits that Hitler's policies might have been wrong, but still deserved obedience.
Sith and Nazi philosophies also glorify violence. Combat for both was seen as a means of proving individual and collective worth. In Germany, the military became the most noble calling and the state trumpeted the Wehrmacht's glorious victories. The Sith seem to take a more elite approach to violence, whereby only Dark Side Force users are expected to excel. We see Sith like Darth Maul become proficient in dueling and killing, but Stormtroopers seem unable to ever hit their mark.
For the Sith, this obsession with power led to the infamous Rule of Two, in which Bane advises:
In other words, there is an ingrained expectation that the Apprentice will rebel once he/she gains enough power to defeat the Master. Unlike Eichmann, obedience for the Sith seems contingent upon the ruler maintaining his power. once the ruler shows weakness, the Sith way teaches that the next most powerful should usurp the throne. However, for Bane, limiting the number of extant Sith to two ensured that the Apprentice would only become the Master if he/she had grown powerful enough in his or her own right, not merely in a coalition with weaker allies.
There did not seem to be any equivalent of the Rule of Two in Nazi Germany. Even when it was clear Germany was losing the war and Hitler was relegated to a less public position in government, his position was never threatened (despite several failed assassination attempts). It is not clear what Eichamnn and other Nazis would have though if, say, Heinrich Himmler had seized the state from Hitler. Would Himmler have been accorded the same obedience as the most successful individual? Or was the narrative about success tied to Hitler's personality cult?
Ultimately, Arendt's Eichmann in Jerusalem shows that evil is not simply an abstraction found in sci-fi movies. It happens in reality and it takes shape in many different ways. George Lucas, writing during the 1970s, patterned the Empire and Sith in part on the Nazis. However, in exploring some of the philosophical and cognitive motivations underlying evil, Star Wars goes beyond "comic book" versions of "Nazis" seen in many movies. Rather, the Sith and Empire work so effectively in the movies because, as with Eichmann, the road from good to evil is a much easier path than we'd often care to believe.