In an article on the prospect of a September interest rate hike by the Fed, the NYT pointed out that Esther George, the President of the Kansas City Federal Reserve Board Bank, expressed concern that low interest rates are fueling financial speculation. She has repeatedly given this as a basis for raising interest rates.

It is worth noting that George has never identified an area where prices are obviously out of line with fundamentals. In the two cases in the last 80 years where the collapse of a speculative bubble led to economic downturns, the stock bubble in the 1990s and the housing bubble in the last decade, it was easy for anyone who looked to recognize the bubbles and that they were moving the economy.

In both cases, the wealth generated by the bubbles led to a consumption boom, which would have been difficult to explain any other way. The stock bubble also led to a surge in tech investment as it was a simple matter for people with the right connections, who had no idea what they were doing, to raise hundreds of millions or even billions by issuing stock in Internet start-ups. In the case of the housing bubbles, residential construction hit a post-war high as a share of GDP even as the country's demographics would have suggested it should have been falling.

For these reasons, it was predictable that a collapse of the bubble would lead to a recession, and an especially serious one in the case of the housing bubble. Also, it was easy to see that both were bubbles. In the late 1990s, bubble the price to earnings ratio reached levels that were twice the normal ratio. For this to make sense it would have required either a sustained growth rate of corporate profits that was hugely faster than any forecasters were predicting or a change in investor attitudes to stock, where they were prepared to accept returns that were the same or less than the returns on government bonds. In the case of the housing bubble, with vacancy rates hitting record highs and rents seeing no real increase whatsoever, it was pretty hard to see the run-up in house prices as anything except a bubble.

Given this recent history, it would be reasonable to ask Ms. George where she sees evidence of a dangerous bubble. If her argument is that she wants to slow growth and keep people from getting jobs because of her fear of bubbles, she should be able to produce some evidence to support this fear. To date, she has not. (It's also worth noting that even if we face the risk of a bubble, it is far from clear that higher interest rates are the best tool for addressing the problem.)