John Cochrane’s post on Nobel Laureate Robert Shiller is certainly a contender. It’s long, and you should read the whole thing. Of many possible excerpts, I choose:

No matter where you look, stock, bonds, foreign exchange, and real estate, high prices mean low subsequent returns, and low prices (relative to “fundamentals” like earnings, dividends, rents, etc) mean high subsequent returns.

These are the facts, which are not in debate. And they are a stunning reversal of how people thought the world worked in the 1970s. Constant discount rate models are flat out wrong…

To Fama, it is a business cycle related risk premium. He (with Ken French again) notices that low prices and high expected returns come in bad macroeconomic times and vice-versa. December 2008 was a recent time of low price/dividend ratios. Is it not plausible that the average investor, like our endowments, said, “sure, I know stocks are cheap, and the long-run return is a bit higher now than it was. But they are about to foreclose on the house, reposess the car, take away the dog, and I might lose my job. I can’t take any more risk right now.” Conversely, in the boom, when people “reach for yield”, is it not plausible that people say “yeah, stocks aren’t paying a lot more than bonds. But what else can I do with the money? My business is going well. I can take the risk now.”

To Shiller, no. The variation in risk premiums is too big, according to him, to be explained by variation in risk premiums across the business cycle. He sees irrational optimism and pessimism in investor’s heads. Shiller’s followers somehow think the government is more rational than investors and can and should stabilize these bubbles. Noblesse oblige.

By the way, Cochrane’s post on Lars Hansen is also top notch.