One interesting point that Tim Soutphommasane made in his Weekend Australian article is that social democracy has
never had a political philosopher who has succeeded in offering a comprehensive articulation of [its] principles.
There is nobody with the status of Marx in socialism, Burke in conservatism, or a range of thinkers in the liberal tradition: Locke, Smith, Mill, Hayek. In my political identity survey, more than half of the classical liberal respondents said they had read each of the major liberal thinkers (though I did not ask about Locke).
Tim ends up suggesting John Rawls as the closest social democrats get, but notes that he was an American left-liberal rather than an identifying social democrat. And while Rawls may achieve great thinker status within academia, he is not widely read outside academia by social democrats or anyone else. I found his The Theory of Justice heavygoing; much less accessible than the other liberal books.
If had to nominate a social democrat worth reading it would be Michael Walzer. His Spheres of Justice: A Defence of Pluralism and Equality is a model of how modern political theory should be done. It has insight and interesting arguments on just about every page, and Walzer is a stylish writer. But when I mention Walzer to social democrats they rarely know his work, or know only his writings on just and unjust wars.
There are lots of smart, book-writing social democrats, and even more smart, book-reading social democrats, so this lack of greater social democrat books and thinkers is really a bit odd. But it is consistent with their social democracy being a sensibility rather than something that is book learnt. Books may give details of injustices and suggestions for policies to correct them, but the core social democratic ideas are built on such powerful intuition that social democrats do not find its theory useful. Perhaps theory even drains the core beliefs of passion more than it energises them with insight.
Compared to social democracy, liberalism probably does come from books. My liberalism started with a book, and I don’t think I am too unusual in that regard. There are more counter-intuitive ideas in liberalism – order without central control, putting up with people you disagree with, morality without God or church, etc – than in either social democracy or conservatism. The great thinkers and their books explain the arguments, and are acknowledged as great for pointing out things we didn’t realise before. But social democrats have much less need for such people, and so they have not given high and lasting status to any of their thinkers.