Krugman on Paul Samuelson

As anyone with an interest in economics will know, Paul Samuelson passed away over the weekend. Paul Krugman's tribute reminds us of how much we take as commonsensical is attributable to Samuelson's work:

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 realized 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 generalized comparative advantage concepts of Deardorff, has been based on that insight.

4. Public goods: Why must some goods and services be provided by the government? What makes some, but only some, goods suitable for private markets? It all goes back to Samuelson’s 1954 “Pure theory of public expenditure”.

5. Factor-proportions trade theory: Every time we talk about resources and comparative advantage, every time we worry about the effect of trade on income distribution, we’re harking back to Samuelson’s work in the 1940s and 1950s: he took the vague, confusing ideas of Ohlin and Heckscher, and turned them into a sharp-edged model that defined most trade theory for a generation, and remains a key part of the modern synthesis.

6. Exchange rates and the balance of payments: A bit of personal storytelling: Most people who work in international trade tend to lose the thread when the discussion turns to exchange rates and the balance of payments; as I’ve sometimes put it, the real trade people regard international macro as voodoo, while the international macro people regard real trade as boring and irrelevant (and when I’m in a sour mood, I suggest that both are right). But I was saved from all that when I read Dornbusch, Fischer and Samuelson 1977 on Ricardian trade, which among other things showed how trade and macro, exchange rates and the balance of payments, the possibility of gains from trade but also the possibility of unemployment, all fit together.

In other words this is economics as useful social science rather than applied ideology.