Most people are aware of the fact that governments owe a startling amount of money, and that this is commonly referred to as a “National Debt”. People are also generally aware of the fact that the numbers of dollars or euros involved are so staggering that they are in fact meaningless, when quoted in isolation.
For instance, the US national debt currently stands at about $15,500,000,000,000 which to you (and me) just looks like 1,55 with a lot of zeros attached to it. If I told you it was
$15,500,000,000,000,000 you would not have been any more or less shocked.
Which is why debt is often expressed as a proportion of GDP. We are alarmed when we hear that debt has reached 75% of GDP, or even 100% of GDP. Some people even panic when they hear this.
Then we find ourselves asking: Is such a level of debt sustainable? Is it time for me to build a bunker and stock it with canned food, backup generators and shotgun shells?
Well, as for the second question, canned food is always a good thing to have in the house, but please check local laws regarding the shotgun shells.
As to whether debt is sustainable, it makes more sense to think of it this way:
GDP is the value of everything the country produces in one year. Debt is the money it owes. As long as new creditors can be found, debt can be rolled over infinitely. The only cost of doing this is the interest the government has to pay on the debt.
So, if debt were a really high 100% of GDP (Italy, Belgium,…) then the debt servicing costs would amount to 4 or 5% of GDP.
Is that alot? Well, yes and no. In proportional terms, the US spends more on its military (6.8% of GDP) than Belgium spends servicing its very high debt.
You may say: “Hold on, you are not comparing like with like. Paying interest on rolled over debt is like throwing money out the window, while the US military is providing jobs, and defending our country from evil-doers.”
Without getting into a debate on the efficacy of defense spending, let me just point out two things: paying interest on debt is NOT like throwing money out the window. It is much more like rewarding investors who have placed their trust in the government as a good investment for their money. And the interest rates are generally very low. Before the govenment goes paying down the principal, you have to consider the opportunity cost of doing so. Paying off debt is like investing in something with a very low interest rate. The government has to ask, is there anything else we can spend that money on (like education or infrastructure) that will provide a higher return than the 4% dividend we save by buying back our own T-bonds?
Moreover, think about this: if every taxpayer owned an share of the debt equal to his tax obligations, the level of public debt would have no impact on the country whatsoever.
Natural limits to debt
What is the highest debt can go? I have heard people say, 100% of GDP. Of course that is a logical error. Beyond the fact that the GDP tells you the size of a country’s economy, debt and GDP have no direct relationship, and GDP is only picked as a denominator out of convenience.
The thought exercise of what the real limit of debt is can be useful when we want to put the overall debate into perspective. So how high can it go?
The answer is actually 2,000% of GDP.
In the case of the US government that would be $2,900,000,000,000,000 (which I think is 2.9 gazillion!); a staggering eighteen times the current debt level. This is because this is the maximum amount of money the government can roll over continuously by paying interest (at 5%) using all of the country’s GDP to do so.
At this limit, all of the countries GDP would have to be taken in tax and used to service the debt.
Here’s the thing: even at this debt level, if the money is distributed perfectly evenly, there is no real burden to the economy of having so much public debt. (Obviously though, any small distortions in the structure of capital holdings will lead to radical pro-capital / anti-labour outcomes.)
So for those of you fretting about the high levels of debt, don’t worry, be happy. We still have gazillions of irresponsible government spending to go before we reach a hard theoretical limit!