I accused John Cochrane of incoherent babbling on the Federal deficit issue noting his update where he flip flopped:

He went from fiscal policy being sober to we are in dire straights just like that! Oh my the sky is falling. We have to take away those Social Security benefits that my generation have been paying into for 35 years. We cannot afford Federal health care spending. After all those tax cuts for the rich can never be reversed. Yes John Cochrane is part of the Starve the Beast crowd even if granny starves from these supposedly required reductions in transfer payments.

But let’s note why Cochrane flip flopped in his update:

Jeff Miron wrote to chide me gently for apparently implying the opposite, which is certainly not my intent. One graph from his excellent “US Fiscal Imbalance Over Time”.

Having read this Cato paper, it is time for my critical review that I promised. The review will start with the technical finance which in one way is a lot better than Cochrane’s rants but still troubling in certain ways. I will next turn to the policy if not political issues where this paper is even worse than Cochrane’s update. Beware – we will have to cover a fair amount of numbers but I hope to keep this within the context of my present value model:

Let g = the ratio of Federal expenditures excluding interest payments to GDP and t = the ratio of Federal taxes to GDP. If we assume a steady state model, the present value of future primary surplus is simply V = (t- g)/(r – n), where r = the real interest rate and n = the long-term growth rate. As long as V is at least as great as the debt/GDP ratio, we are not on the bankruptcy path that economists were talking about when Reagan initiated his 1981 fiscal fiasco. Tax rates were massively cut and defense spending spiked and had this fiscal stance continued forever, then the debt/GDP ratio would have exploded. Of course it didn’t as there were future tax increases and the peace dividend.

Miron is using the same basic model, which he expresses as:

Fiscal Imbalance = Present Value of Future Expenditure – Present Value of Future Revenue + Outstanding Debt

What I like about this equation is its focus on future spending and revenue not historical decisions which can be summarized as the current level of debt in terms of our model. Cochrane’s rant was a bit weak in this regard. May I suggest Cochrane rent the 1989 movie and check out this scene as the Joker gets basic finance! While I may quibble with Miron with respect to his forecasts, my big problem the use of nominal figures to draw his graph – which is far from “excellent”. Note his measure doubled in nominal terms since 2000 but so has nominal GDP (higher prices, more people, and higher income per person). Which is why this title and introduction is misleading: