Opinion | The Short-Sighted Economic Populism of Harris and Trump

At her speech on economic policy in Raleigh, N.C., this month, Kamala Harris uncorked a beautiful riff that slammed a certain policy proposal as nothing more than a “national sales tax” on the American public, one that would raise the price of “everyday products and basic necessities” and cost the typical family $3,900.

For once, a presidential candidate was speaking like an economist — or at least, a practical policymaker with a realist’s grasp of supply and demand.

The proposal she knocked was that of her opponent, Donald Trump — namely, a tariff of as much as 20 percent (and considerably higher on Chinese imports). Vice President Harris got it right: Tariffs are a tax, paid by American consumers. They make the country poorer. When Mr. Trump tried them, he created no new net jobs, and American consumers, including employers that depend on foreign steel, were stuck with higher prices, hurting homegrown industry.

Moreover, other nations retaliated against U.S. exports. In retrospect, America produced a little bit more in areas where it is less competitive, such as washing machines, and sold less of what it does best, such as soybeans. That nonsensical result is why Mr. Trump’s proposed tariff expansion remains one of the two worst ideas to surface in the campaign.

Unfortunately, the other one was unfurled in the same speech, and with equal violence to free market principles. Ms. Harris promised to seek federal authority to control food prices. Where she was hard-hitting and specific in describing Mr. Trump’s failed tariff policy, she was censorious and vague in pitching price controls. She wouldn’t go after all companies — only “bad actors” that “exploit crises” by “price gouging.”

Forget that her proposal addresses a problem that no longer exists (over the past year, food prices rose a mere 1 percent) and that supermarkets operate on notoriously thin margins. More dismaying was her seeming ignorance that price controls, almost without exception, have led to shortages, supply chain disruptions and eventually higher prices. When Ms. Harris pledged to crack down on “opportunistic” offenders and restrict “excessive corporate profits,” she seemed unaware that exploiting opportunities for profit is exactly what private enterprise is intended to foster (Henry Ford, Steve Jobs, Warren Buffett — opportunists all).