It's unfortunate that populism has a name that leads to this misconception. People see the word and jump into discussion assuming that they know what is all about.

Populism is the claim that the people have a 'will'. There is no real disagreement of what the real people want or need for compromise. There are people who disagree but they are not the 'real people'. They are somehow compromised, the corrupt elite, misled or 'the others'. What 'people want' is already known, now you just need to vote populist into power to implement the will of the people. Laws and norms often make it difficult to implement this 'will' and they should be changed.

By contrast liberal[1] democracies are based on idea that the complex democratic process gradually produces something that people can live with. It's not exactly what anyone wants. There is no common agreement of what people want when people go and vote. The end result of working democracy is negotiated compromise. Laws and norms should be followed when this game of democracy is played.

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[1]: liberal is another word that have different meanings in different contexts. Liberal does not mean leftist in this context.