Kevin Williamson has a long-overdue piece in National Review making two essential points about supply-side economics and the Laffer Curve. First, he explains that tax cuts are not the fiscal equivalent of a perpetual motion machine. Simply stated, too many Republicans have fallen into very sloppy habits. They oftentimes fail to understand the difference between “supply-side” tax rate reductions that actually improve incentives to engage in productive behavior and social-engineering tax cuts that simply allow people to keep more money, regardless of whether they create more wealth. This does not necessarily mean the latter form of tax cuts are bad, but they definitely do not boost economic performance and generate revenue feedback. Moreover, even when GOPers are talking about supply-side tax cuts, they frequently exaggerate the positive effects by claiming that lower tax rates “pay for themselves.” I certainly think that can happen, and I give real-world examples in this video on the Laffer Curve (including Reagan’s lower tax rates on those evil rich people), but self-financing tax cuts are not common.

Williamson’s second point is that the true fiscal burden is best measured by looking at how much government is spending. I might quibble with his description of deficits as a form of deferred taxation since technically debt can be rolled over in perpetuity, but his main point is right on the mark. There is no doubt that most forms of government spending – regardless of the means of financing – harm growth by diverting money from the productive sector of the economy (technically, the economic damage occurs because capital and labor are misallocated and incentives are diminished, but let’s not get too wonky). Here are some excerpts from Williamson’s article:

Properly understood, there were no Reagan tax cuts. In 1980 federal spending was $590 billion and in 1989 it was $1.14 trillion; you don’t get Reagan tax cuts without Tip O’Neill spending cuts. Looked at from the proper perspective, we haven’t really had any tax cuts to speak of — we’ve had tax deferrals. …even during periods of strong economic growth, there has been nothing to indicate that our economy is going to grow so fast that it will surmount our deficits and debt without serious spending restraint. This should be a shrieking klaxon of alarm for conservatives still falling for happy talk about pro-growth tax cuts and strategic Laffer Curve optimizing. …The exaggeration of supply-side effects — the belief that tax-rate cuts pay for themselves or more than pay for themselves over some measurable period — is more an article of faith than an economic fact. But it’s a widespread faith: George W. Bush argued that tax cuts would serve to increase tax revenues. So did John McCain. …It is true that tax cuts can promote growth, and that the growth they promote can help generate tax revenue that offsets some of the losses from the cuts. …The problem with magical supply-siderism is that it gives Republicans a rhetorical and intellectual framework in which to ignore spending — just keep cutting taxes, the argument goes, and somebody else will eventually have to cut spending. The results speak for themselves: Tom DeLay and Dennis Hastert and Trent Lott and Bill Frist all know how to count, but, under their leadership, Republicans spent all the money the country had and then some.

Now that we’ve chastised Republicans, it’s time to turn our attention to the Democrats. We know they are bad on spending (I often joke that Republicans expand government out of stupidity, while Democrats do it for reasons of malice), so let’s focus on their approach to Laffer Curve issues. If the GOP is guilty of being too exuberant, the Democrats and their allies at the Joint Committee on Taxation (the bureaucracy on Capitol Hill that estimates the revenue impact of tax policy changes) are guilty of deliberate blindness. The current methodology used by the JCT (with the full support of the Democrats) is to assume that changes in tax policy – regardless of magnitude – have zero impact on economic performance. If you double tax rates, the JCT assumes the economy is unaffected and people earn just as much taxable income. If you replace the IRS with a flat tax, the JCT assumes there is no effect on macroeconomic performance. Sounds unbelievable, but this video has the gory details, including when my former boss, Senator Bob Packwood was told by JCT that revenues would rise year after year even if the government imposed a 100 percent tax rate.

Interestingly, the European Central Bank just released a new study showing that there are substantial Laffer Curve affects and that lower tax rates generate large amounts of revenue feedback. In a few cases (Sweden and Denmark), the researchers even conclude that some lower tax rates would be in that rare category of self-financing tax cuts. But the key point from this ultra-establishment institution is that changes in tax rates do lead to changes in taxable income. This means it is an empirical question to determine the revenue impact. Here’s a key excerpt from the study’s conclusion:

We show that there exist robust steady state Laffer curves for labor taxes as well as capital taxes. …EU-14 countries are much closer to the slippery slopes than the US. More precisely, we find that the US can increase tax revenues by 30% by raising labor taxes but only 6% by raising capital income taxes, while the same numbers for EU-14 are 8% and 1% respectively. …We find that for the US model 32% of a labor tax cut and 51% of a capital tax cut are self-financing in the steady state. In the EU-14 economy 54% of a labor tax cut and 79% of a capital tax cut are self-financing. We therefore conclude that there rarely is a free lunch due to tax cuts. However, a substantial fraction of the lunch will be paid for by the efficiency gains in the economy due to tax cuts.

Contrary to over-enthusiastic Republicans and deliberately-dour Democrats, the Laffer Curve/supply-side economics debate is not a binary choice between self-financing tax cuts and zero-impact tax cuts. Yes, there are examples of each, but the real debate should focus on which types of tax reforms generate the most bang for the buck. In the 1980s, the GOP seems to have the right grasp of this issue, focusing on lowering tax rates and reducing the discriminatory tax bias against saving and investment. This approach generated meaningful results. As Nobel laureate Robert Lucas wrote, “The supply side economists, if that is the right term for those whose research we have been discussing, have delivered the largest genuinely free lunch that I have seen in 25 years of this business, and I believe we would be a better society if we followed their advice.”

But identifying and advocating pro-growth tax reforms, as Williamson notes, is just part of the battle. The real test of fiscal responsibility if controlling the size of government. Republicans miserably failed at this essential task during the Bush year. If they want to do the right thing for the nation, and if they want to avert a Greek-style fiscal collapse, they should devote most of their energies to reducing the burden of government spending.