There have been hedgehogs; there have been foxes; and then there was Paul Samuelson.
I’m referring, of course, to Isaiah Berlin’s famous distinction among thinkers – foxes who know many things, and hedgehogs who know one big thing. What distinguished Paul Samuelson as an economic thinker, making him like nobody else, past or present, was the fact that he knew – and taught us – many big things. No economist has ever had so many seminal ideas.
With a little help from Google Scholar, I’ve compiled a list of some of Samuelson’s big ideas. I say “some” because I’m sure it’s not complete. But anyway, here are eight – eight! – seminal insights, each of which gave rise to a vast and continuing research literature:
1. Revealed preference: There was a revolution in consumer theory in the 1930s, as economists realised that there was much more to consumer choice than diminishing marginal utility. But it was Samuelson who taught us how much can be inferred from the simple proposition that what people choose must be something they prefer to something else they could have afforded but don’t choose.
2. Welfare economics: What does it mean to say that one economic outcome is better than another? This was a blurry concept before Samuelson came in, with much confusion about how to think about income distribution. Samuelson taught us how to use the concept of redistribution by an ethical observer to make sense of the concept of social welfare – and thereby also taught us the limits of that concept in the real world, where there is no such observer and redistribution usually doesn’t happen.
3. Gains from trade: What does it mean to say that international trade is beneficial? What are the limits of that proposition? The starting point is Samuelson’s analysis of the gains from trade, which drew on both revealed preference and his welfare analysis. And everything since, from the distortions analysis of Bhagwati and Johnson to the generalised comparative advantage concepts of Deardorff, has been based on that insight.