ARNOLD KLING: U.S. Government Bonds are Junk Bonds.

If you buy a ten-year U.S. government bond, what are the chances that you will be repaid in full? Are they 99 percent or more?

If we are talking about being paid back in dollars, I would say that the answer is “yes.” But what about the purchasing power of those dollars?

To keep the arithmetic simple, suppose that you invest $100 in a bond, and you get no interest until the bond matures. Interest is, say, $5 per year, so that in ten years, when the bond matures, you get $150.

Suppose that $150 ten years from now will buy the equivalent of $100 today. Then you just break even on the bond. That corresponds to inflation of roughly 5 percent per year, not compounded. If inflation is less than that, you do better than break-even, and if it is more than that, you do worse.

I think that it is fair to say that if inflation averages more than, say, 8 percent over the next ten years, then long-term government bonds that you buy today will have effectively defaulted. So if you are going to rate long-term government bonds as being investment grade, you have to assign a very low probability to such a high-inflation scenario.

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