When Arendt arrived in Jerusalem, she said to her mentor and former teacher, Karl Jaspers, I have to go and look at this man face to face and try to work out what’s happening.

She thought the trial was terribly important because it did things the Nuremberg trial wasn’t able to do. She understood that the unprecedented nature of the Nazi crime produced new challenges for law, for judgement and (you guessed it) for thinking. She was very worried about Nuremberg because she thought that this was a new crime. How are we going to judge it? We can’t judge it using old tools. We’re going to have to learn.

This is the first time she uses the phrase to “think without bannisters”. She goes to Jerusalem to think without bannisters. She sees Eichmann in his glass box. On the first day that she saw him, he had a cold. He was a middle-aged guy, he’d forgotten which glasses he had on and he was chuntering clichés. He seemed to have no sense of where he was or who he was talking to, though that’s not to say he was stupid or clueless. (And, actually, I think she got him wrong. He was far more cunning than she gave him credit for.) What she said was that this is a man who’s done this extraordinary evil and who has no thought about it. He did it unthinkingly. She said – and I’m trained as a literary critic, so this is very important to me – that it comes across in his language. He’s just using self-aggrandising, ridiculous clichés. He’s like your worst uncle at the worst wedding ever, lecturing you on Brexit or Trump.

Arendt’s definition of a crime against humanity is very interesting. She says a crime against humanity is a crime against human diversity. I think that’s something really worth holding onto. But Eichmann wasn’t, as it were, a kind of radically evil person who had talked himself into doing wrong.

She compares him to Shakespeare’s Richard III. There’s that wonderful soliloquy near the beginning of Richard III, where Richard’s persuading himself to do crime. Shall I prove myself a villain? Am I a villain? OK, I am. It’s in this inner dialogue that Richard decides that he will be a villain.

Eichmann, Arendt says, has no sense of that inner dialogue whatsoever. That is his banality: the banality of radical thoughtlessness. Eichmann is full of these explosive comments, which are completely banal. He’ll say things like, ‘I can’t stand the sight of blood. I once went to a camp and saw some blood moving up from the mud and I nearly fainted.’ Or, ‘I’m a great humanitarian. I could see that there were too many people in those cattle trucks, so I decided there should be fewer people in the cattle trucks.’ He was sending them to their deaths!

It’s not just institutions but also social life that can produce these kinds of banal thoughtlessness. Arendt is often misunderstood. She believed quite dogmatically in divisions between private life, which she wanted to protect, the social, which she thought was tyrannical, and the political realm, where she wanted people to make judgements. She saw the social as attacking both politics, in which all politics becomes a question of social tastes or norms, and, just as catastrophically, private life.

As a feminist, you might have issues with this because a lot of what happens to women, as well as a lot of race struggles, are based on what happens in private life, which doesn’t get to see the light of day. But if we think about the growth of the social, we think about how social media has pushed out a sense of politics being a space for debate and for accountability, and how it has encroached radically on our private lives. There’s not a moment when we’re not somehow performing a version of ourselves for social consumption.

So, this isn’t about bureaucratic, heavy-handed Soviet or Nazi institutions. It’s about what happens in our versions of the social, and, as Arendt would add, what happens to political accountability in that mode.

There’s a sense, and I’m not the only person to commentate on this, in which we’ve almost switched over. What should be publicly known – who gets what contract, how things are being paid for, who owns the money, what kind of system is working for which politicians – is now going to be private. Those are considered private questions that we can’t ask our politicians. It’s completely switched around from the way that Arendt thought it should be. We need to be very watchful about that. When Arendt uses that phrase “an attentive facing up to reality”, maybe the key word there is “attention” – attending to what is happening in front of us, rather than this endless consumption and creation of social anxiety and social pleasure, which blinds us to what is happening.