From this very smart Will Wilkinson post about Rawls (Will has a real habit of being right about important stuff), the following odd judgments.
Who are the greatest political philosophers of the past few centuries, according to my idiosyncratic judgment? 19th C.: Herbert Spencer (maybe the most unjustly maligned thinker ever) by a hair over J.S. Mill and Henry Sidgwick. 18th C.: David Hume over Adam Smith by a nose. 17th C.: Thomas Hobbes by a nose over John Locke, for reasons similar to Rawls vs. Nozick.
Well, Hobbes, certainly. I understand the appeal of Spencer but can't share in that judgment-- and for Sidgwick to be even a close third reflects an unacceptable deviationism brought on by Will's training as a political philosopher rather than a political theorist. (Is Sidgwick meaningfully political at all? Can he rival Constant, Tocqueville, Hegel, or Marx?)
The second half of the 18th century saw breakthrough after breakthrough in the human sciences-- political theory, political philosophy, political economy, and political science, but also moral philosophy, moral psychology, epistemology, and also historical sociology, jurisprudence, etc., etc. In the human sciences taken in aggregrate, four of the greatest thinkers in western history wrote their major works in something like a forty-year timespan: Hume, Rousseau, Smith, and Kant. I submit that there hadn't been anything quite like that concentration of intellectual greatness in these fields since Plato and Aristotle. And qua philosophers, Hume and Kant tower over even Rousseau and Smith.
But as political philosophers? No. Smith and Rousseau tower over Hume and Kant, as important as the work of the latter two was. Please, Will, an explanation and defense...