Truth be told, economists have been making these arguments for years. None has yet come true. It’s conceivable that they might never come true. The global demand for so-called “safe assets” — financial securities that investors can trust — might sustain a growing worldwide supply of U.S. Treasury securities that, despite our problems, are still regarded as highly reliable. If so, we could cut taxes and not worry about deficits.

But that’s a huge gamble on the future. Do we really want to bet that what seems true today will be true a decade and roughly $15 trillion more in government debt from now? Prudence suggests not. If we lose the bet, the outcome might make the 2008-2009 financial crisis and Great Recession look like a cakewalk.

Taxes will ultimately follow spending upward. Even if some programs are cut, the popularity of most programs — led by Social Security and Medicare — and an aging population ensure that government spending as a share of the economy will rise.

Not to worry, says Treasury Secretary Steven Mnuchin. Trump’s tax cuts “will grow the economy and will create . . . trillions of dollars in additional revenues.” It’s painless.