I've come late to this updated 'classic' popular psychology book from 2021, updating the 2008 original. If I'd read it when the first version came out, I would probably have been really positive about it. Much of what's in here sounds very sensible and effective. And all sorts of people followed the concept of 'nudging', from hotels telling us that most people reuse towels to reduce laundry costs to governments setting up 'nudge units' like the UK's Behavioural Insights Team. But the reality has proved rather different from the assertions made here. One problem is sorting out what a nudge is . According to Richard Thaler and Cass Sunstein, a nudge should 'alter people's behaviour in a predictable way without forbidding any options or significantly changing their economic incentives.' Nudges should be both easy and cheap, making them 'libertarian paternalism'. There is no doubt that some nudges work, some do something but not w...