Arendt used the words ‘the banality of evil’ to describe what she saw in Eichmann. If something is ‘banal’, it is common, boring and unoriginal. Eichmann's evil was, she claimed, banal in the sense that it was the evil of a bureaucrat, of an office manager, rather than a devil. Here was this very ordinary sort of man who had allowed Nazi views to affect everything he did.
