The CBO currently estimates potential real GDP at the end of 2022—what we would expect without policy changes to boost economic growth—to be $18.5 trillion real dollars. Current real GDP is $13.5 trillion. Applying HHMT’s lower-range growth numbers produces an end-of-2012 real GDP not $2.1 trillion higher than CBO projects but rather $0.6 trillion higher. $1.5 trillion of their claims thus arise not from faster growth of the economy’s productive potential but from an implicit—and unmotivated—assumption that under Romney policies aggregate demand in 2022 is equal to potential output, but under other policies it is not.Interestingly, 5.4% of CBO’s $18.5 trillion in potential GDP would represent a $1.0 trillion improvement. But how does Diamond get there. He assumes a specific policy of tax rate reductions with tax revenue offsets (“base broadening”). His model also ignores any crowding-out effects which must mean that any failure to offset the rate reductions were paid for by cuts in government spending. Again, let’s turn the microphone back over to Brad:
Similarly, Romney has not even the outlines of a plan for how to reduce federal spending to 20% of GDP, or how he could possibly broaden the tax base to keep his tax cuts for the rich revenue-neutral. If you do indeed fear uncertainty about tax and regulatory policy, you need to vote against Romney as you would vote against the plague—and urge everybody you know to vote against Romney, and urge them in the strongest possible terms.I’m sure Team Romney will tout the results of the paper from Diamond but something tells me that they are not going to be so willing to address the legitimate questions about whether their alleged policy proposals match the assumptions made in this paper. If they don’t – this is not a real policy debate. It is just propaganda dressed up to look like economics. Didn’t we see this movie back some 32 years ago?