George Mason University economists Tyler Cowen and Alex Tabarrok, who run Marginalrevolution, one of the most popular and—in my opinion—best blogs on the internet, have recently made forays into online education. Their latest is on the history of economic thought, looking at great economists from Galileo up until the marginal revolution of the 1870s, tackling questions including "Why is Adam Smith the greatest economist of all time?"

Here is the introduction to their course: