President Ronald Reagan, left, the conservative standard-bearer with deep libertarian notes, and President Barack Obama, right, who wants to be the liberal big government standard-bearer, with deep modern liberal notes, which Reagan said resembles fascism.

Is “supply-side economics” a bad thing or good thing? It depends on what one means by the phrase. If it means that all tax cuts are self financing or that low tax burdens are the sole key to prosperity, then critics are right about it being a form of “voodoo economics.” See this Kevin Williamson column for more details.

But if the term is simply a shorthand way of saying that low marginal tax rates on productive behavior are a good thing because of better incentives for work, saving, investment, and entrepreneurship (not to mention tax compliance and good government), then supply-side economics should be non-controversial. See this piece by Alan Reynolds for more details.

As you might expect, folks on the left prefer the first definition of supply-side economics and they are instinctively hostile to big tax cuts. Especially during an election cycle.

Here’s the basic argument, from an article by John Cassidy in The New Yorker. He focuses his ire on Governor Bush, but his comments could just as easily been directed against other GOP candidates.

Here’s his basic premise.

…the Republican Party is heading on economic policy: back to the old-time religion of tax cuts. …Jeb Bush, the G.O.P. establishment’s standard-bearer, announced, as the centerpiece of his 2016 campaign, a plan to cut federal income-tax rates across the board. …wouldn’t this plan inflate the deficit, which President Obama and Congress have just spent five years trying to reduce, and also amount to another enormous handout to the one per cent? Not in the make-believe world of “voodoo economics”.

Mr. Cassidy is particularly incensed by the notion that some people believe tax cuts “pay for themselves” by generating sufficiently large amounts of additional taxable income.

The “voodoo” accusation arose from the claim that, because the policies would encourage people to work harder and businesses to invest more, a lot more taxable income would be produced, and the reductions in tax rates wouldn’t lead to a commensurate reduction in the amount of tax revenues that the government collected. Indeed, some early voodoo economists, such as Arthur Laffer, claimed that there wouldn’t be any drop in revenues. By 1988…more than half a decade of gaping budget deficits had discredited the most extreme and foolhardy version of voodoo economics.

For what it’s worth, there are several problems with the above passages.

First, while some GOPers did make exaggerated claims about the power of tax cuts, the Reagan White House never claimed the tax cuts would by self financing and instead made the very reasonable argument that lower tax rates would improve economic performance.

Second, the lower tax rates on upper-income taxpayers did lead to huge increases in taxable income and big increases in tax revenue, so there are a few examples where lower tax rates “pay for themselves.”

Third, the 1980-1982 double-dip recession was the main reason for higher deficits. Once the Reagan tax cuts were implemented, red ink began to shrink and even the Congressional Budget Office projected deficits would continue falling if Reagan’s policies were left on auto-pilot. But let’s argue about the present rather than the past. Citing the work of some pro-Bush economists, Cassidy argues that tax cuts won’t generate as much growth as Governor Bush says he will deliver.

…the four conservative luminaries whom the Bush campaign rounded up to advise him…said that Bush’s tax plan would raise the growth rate of the economy by 0.5 per cent a year, and that the regulatory changes he is proposing would add another 0.3 per cent to the annual growth rate. But because the annual growth rate over the past five years has been 2.2 per cent, that gets us to three per cent growth, not the four per cent that Bush is promising to deliver.

Since economists are lousy forecasters, I won’t pretend to know how much additional growth the Bush economic plan would produce. But I’ll be the first to admit that Cassidy has found a gap between Bush’s rhetoric and the numbers produced by his advisers.

But does that mean big tax cuts are implausible and unrealistic?

Cassidy certainly would like readers to conclude that Bush’s plan doesn’t add up.

…the economists’ paper…makes the familiar argument that tax cuts, by stimulating growth, will lead to “revenue feedbacks.” On this basis, which is known on Capitol Hill as “dynamic scoring,” the economists reduce the estimated fiscal cost of the Bush tax cuts by two-thirds. But even a third of $3.6 trillion is a lot of red ink.

Though he (sort of) acknowledges that the Bush folks have a counter-argument.

So are the economists actually contradicting Bush and saying that his plan would expand the deficit? Not quite. …they write, “The remaining revenue loss would be offset by reasonable, incremental feedback effects from the tax and regulatory reforms, meaningful spending restraint across the federal budget…” Of course, Bush hasn’t said yet where he would cut spending

I don’t know if Governor Bush intends to produce a detailed list of ways to restrain government spending. Nor do I know whether he would follow through if he got elected (his record in Florida can be interpreted in different ways). But I know that it’s actually very simple to have large tax cuts along with concomitant spending restraint.

And Bush’s economic advisers also understand. Take a look at these passages from their report. Citing a version of my Golden Rule, they point out that huge savings are possible simply by reducing how fast the government’s budget expands every year.

Budget discipline and economic prosperity go hand in hand. …federal spending restraint is essential to maximizing economic growth. …the Governor’s economic reforms require strong fiscal discipline on the federal budget ledger’s spending side. …the required budget goal can be achieved by reducing the growth in federal outlays from its current upward trajectory by one percentage point per year. From 2017 to 2025, federal expenditures are projected to increase at an annual rate of 4.2 percent. Limiting the increase to 3.2 percent will produce over $400 billion in budget savings in 2025 and $1.4 trillion in savings between 2017 and 2025.

Needless to say, we should have big–and immediate–reductions in government spending. And if government is allowed to expand, it would be better if the budget grew at the rate of inflation (2 percent) rather than 3.2 percent. That being said, it’s remarkable that even a little bit of spending restraint is capable of generating huge savings over a 10-year period. And those savings make big tax cuts very plausible. Even for the folks who myopically fixate on red ink when they should be worried about the overall burden of government spending.

So the real issue is not whether sizable tax cuts are plausible. It’s whether advocates of good tax policy are willing to impose accompanying discipline on the spending side of the fiscal ledger. That means a President like Ronald Reagan or Bill Clinton rather than George Bush or Barack Obama. Interestingly, Jeb Bush admits spending grew too fast while his brother was in office. Check out what he said toward the end of this interview.

For what it’s worth, I think the Bush White House was just as guilty as the GOP Congress, if not more, but that’s another fight over what happened in the past. What really matters is that if Jeb Bush (or any other candidate for President) is serious about charting a different path and putting government on a diet, then big tax cuts are very realistic.