I respect Jim Hamilton a lot, so I take his criticism seriously — and he raises questions that others raise too about my relatively sanguine assessment of the debt situation. Yet I think that he and others are quite wrong, on several counts.

First off: the assertion that the post-World War II debt was sui generis, that it offers no guidance on what we can afford. It’s true that right after the war it was possible to get a drastic reduction in spending easily, since we didn’t have to fight the Axis any more. But let’s take a slightly later start date: in 1950, federal debt in the hands of the public was 80 percent of GDP, which is in the ballpark of what we’re looking at for 2019. By 1960 it was down to 46 percent — and I haven’t heard that anyone considered America a debt-crippled nation when JFK took office.

So how was that possible? Was it through drastic cuts in defense spending? On the contrary: we’re talking about the height of the Cold War (with a hot war in Korea along the way), and federal spending actually rose as a share of GDP. So yes, it wasn’t entitlement programs, but it wasn’t exactly discretionary either.

How, then, did America pay down its debt? Actually, it didn’t: federal debt rose from $219 billion in 1950 to $237 billion in 1960. But the economy grew, so the ratio of debt to GDP fell, and everything worked out fiscally.

Which brings me to a question a number of people have raised: maybe we can pay the interest, but what about repaying the principal? Jim gets scary numbers about the debt burden by assuming that we’ll have to pay off the debt in 10 years. But why would we have to do that? Again, the lesson of the 1950s — or, if you like, the lesson of Belgium and Italy, which brought their debt-GDP ratios down from early 90s levels — is that you need to stabilize debt, not pay it off; economic growth will do the rest. In fact, I’d argue, all you really need to do is stabilize debt in real terms.

So where Jim Hamilton has us paying $1 trillion a year to service $9 trillion in debt, I have us paying $225 billion — 2.5% real interest on that sum.

Now, how does that compare with the tax base? Hamilton rather mysteriously compares debt service only with current personal income taxes. If we use the overall tax take, and talk about what that tax take will be a decade from now, things look much less severe.

So: in 2008, with revenues already depressed by the recession and housing bust, the federal government took in $2.5 trillion in revenues. If we assume 2.5% real growth* and 2% inflation, by 2019 that would rise to $4 trillion. So debt service costs due to the next decade’s deficits would be less than 6 percent of revenue under current law.

So, to review: to make the debt look scary, you have to dismiss the post-World -War II experience, even though it turns out that the 50s offer a quite good lesson; assume that in the future the federal government will have to amortize debt over a quite short period, even though it never had to in the past; compare this inflated debt burden with a narrow piece of the federal tax base; and ignore the likely growth in the tax base over the next decade.

I’m not convinced.

*Contrary to what some think, we’d actually expect growth over the next decade to be somewhat above trend, as the economy picks up some of the current slack. That’s what the historical record tells us actually happens.