There are various costs to high inflation, including things like menu costs, so called because if prices are constantly changing, then things such as menus will need to be continually revised. Seems like a little thing, but we’ve only got so much mental attention to spare, and if we’re constantly thinking about prices, then we have less attention for other things.
Even more important, though, is the fact that high inflation tends to be highly volatile inflation.
If everyone knew that inflation would be precisely 20% next year, not a single basis point more or less, then that wouldn’t be much of a problem for investment. We’d just tack a 20% inflation premium on top of all loans, and that would be that. A hassle, but not an insurmountable one. But what if we expect inflation to be 20%, with an error of plus or minus 5%? What if we’re looking at a window of 15-25% for expected inflation next year?
If inflation is at 2%, then that window of expectations is extraordinarily narrow. Our expectations might be wrong, but they won’t be wrong by much. Inflation could be a little higher than expected, but probably not much higher. If inflation is running 20%, though, that confidence runs right out the window. High inflation is volatile inflation, and that volatility can cause concern for both borrowers and lenders. If I’m borrowing money at 20%, and inflation only turns out to be 15%, then I’m screwed. What I thought would be eaten away by an inflation premium turns out to be a higher real debt burden. And if actual inflation is 25%, then the bank is screwed. They didn’t charge enough for the loan. Bad juju, all around.
A lot of people say this.
I don’t really like it when people say this. It’s not especially precise.
If the price of a gallon of milk is four dollars, then the price of a dollar is 1/4 a gallon of milk. The “price” of money is how much stuff that the money buys. After all, I can potentially lend and borrow in gallons of milk. I can write a contract borrowing 100 gallons of milk today, with the obligation to pay back 105 gallons of milk next year. But that doesn’t mean that the price of milk is 5%. The price of milk is still four dollars. The price of a dollar is still 1/4 a gallon of milk.
The interest rate is not the price of money, in this sense. It is the price of credit. Different thing. That price of credit could potentially apply to any commodity that is borrowed and paid back, not just money. It’s simply normal to borrow money, since it’s the most liquid instrument available.
And I really, really, really want to emphasize here that interest rates can be highly misleading. Interest rates were extraordinarily high in the 70s, based on high expected inflation because money was way too loose (and the oil shocks didn’t help with that, of course). That’s a key point: money was too loose. An extended period of time with high interest rates is a sign that money is too loose. And Volcker stepped in by doing what? Exactly what deltasigma said: he raised interest rates.
Interest rates can be highly, highly misleading. To borrow an analogy from Nick Rowe: It’s like balancing a tall pole on your open palm. If you want to walk backward, then first, you push your palm forward. Volcker lowered interest rates, by first increasing interest rates. Inflation finally came down, and interest rates were much lower than before. But the lower interest rates after Volcker were not a sign of looser money. Money was much tighter under Volcker, which is exactly why inflation came down.
In the same sense, an extended period of very low interest rates is not a sign that money is easy. We’ve got this pole balanced on the palm of our hands, but we’re up against the wall. That doesn’t mean money is easy. If we look at broader macro aggregates, not just misleading interest rates, we should conclude that money is still tight. We need to focus on nominal aggregates the economy, like the inflation rate or nominal spending. Interest rates are important, of course, but they still tend to confuse people.