Neil Irwin has a nice piece about high asset prices that actually ties into my Wicksell discussion from earlier today.

What Irwin points out is that the price of just about every asset category is now high by historical standards. Bond prices in “safe” countries are very high, which is the same thing as saying that interest rates are very low. But so are prices of risky sovereign debt — Paul De Grauwe points out that Spain’s borrowing costs are now the same as Britain’s. Corporate bond rates are low; stock prices are high; all across the board, assets are up.

The proximate cause is obvious: policy interest rates are very low, and expected to remain low, so money is pouring into alternative assets, driving their yields down too. The question is what you think about this situation.

Quite a few people — including a lot of people on Wall Street, at the BIS, and so on — look at this and say that it’s terrible: the Fed is keeping interest rates “artificially low” and thereby distorting asset prices across the board, and it will all end in grief.

But although I hear the phrase “artificially low” all the time, I don’t think many people who use it have thought through what they mean. What would a non-artificial interest rate be?

Well, we do know from Wicksell what an unnatural rate, which sounds like more or less the same thing, would be: it would be an interest rate set too low in the sense that the economy overheats and we have accelerating inflation. But that hasn’t been happening; yes, there’s a slight uptick in some U.S. inflation measures, but nothing out there that suggests an interest rate that is way too low in this macroeconomic sense.

So what are the people complaining about artificially low rates talking about? Partly that they’re low by historical standards — but there are enough changes in the landscape, from deleveraging to demography, that this isn’t a convincing argument. But the main thing, I think, is those asset prices, which the advocates of tight money think are too high — because they wouldn’t make sense without those “artificially low” interest rates.

In case you haven’t noticed, this is a completely circular argument. Once you accept the possibility that rates belong where they are, or even a bit lower, to correspond to the Wicksellian natural rate, you also conclude that asset prices might make sense; and once you concede that asset prices might make sense, you lose the supposed evidence that rates are all wrong.

And one more thing: where is the wild exuberance that we associate with dangerous bubbles? I don’t see popular TV shows about house-flipping, and CNBC viewership is plumbing new lows.

Mainly, though, there simply isn’t any macroeconomic case for claiming that interest rates are wildly depressed relative to fundamentals, and not much reason to believe that assets in general are overvalued.