Why does Donald Trump think that renegotiating NAFTA is not the height of economic nonsense? Why has Hillary Clinton changed from claiming that the Trans-Pacific Partnership is the “gold standard” of trade agreements (which it never was) to now opposing it outright?

Of course it’s politics — pure politics, unadulterated with facts or nuance.

As one of history’s great economists, Frédéric Bastiat, put it in 1848: “There is only one difference between a bad economist and a good one: the bad economist confines himself to the visible effect; the good economist takes into account both the effect that can be seen and those effects that must be foreseen.”

Trump and Clinton are bad economists indeed. If an American worker loses a job due to a factory moving overseas, they see only the impact on that worker. They neglect the benefit to consumers of buying products for less money, leaving us all with the opportunity to save for retirement or buy a nicer home or safer car or take that island vacation we’ve been dreaming of. They also ignore the many new jobs which are created by the ability of businesses to purchase their inputs at lower cost.

And nobody talks about what should be your fundamental right to buy what you want from whom you want without pandering politicians telling you to pay one-third more because they’re trying to scrounge up some votes in Ohio.

Let’s inject some facts into the discussion: Manufacturing jobs increased in the United States for years after the signing of NAFTA in December 1993. They didn’t decline to pre-NAFTA levels until the economic slowdown of 2000-01.

Technology has been lessening America’s need for certain forms of labor for decades. Two percent of the U.S. workforce is now involved in farming as compared to 90 percent in 1800, 40 percent in 1900, and 12 percent in 1950. Yet with so few American farmers, food is more plentiful and cheaper than ever. Similar changes are occurring throughout our manufacturing economy.

Manufacturing is slowly returning to the United States due to low energy costs allowed by fracking, but onerous taxes and regulations still hold back business formation.

Here in Colorado, we have an advanced, technological economy, a highly educated work force, a fortunate location along a major highway that reaches both Canada and Mexico, the two other signatories to NAFTA — and we gain tremendously from two-way trade with each of them.

Indeed, Canada and Mexico are Colorado’s two largest export markets for goods, at $1.4 billion and $1.1 billion, respectively, in 2015.

According to the Colorado Office of Economic Development and International Trade, 31 percent of Colorado’s exports go to NAFTA partners, up from 19 percent two decades earlier. Our top exports include beef, computers and other industrial machinery, and medical instruments. Our top imports from NAFTA members include vehicles, electric and industrial machinery, and plastics.

Colorado Business Roundtable data shows that 21 percent of jobs in Colorado are supported by trade, double the pre-NAFTA rate and growing more than twice as fast as total employment over roughly the last decade. Colorado’s exports to Mexico and Canada are up about 300 percent since the agreement was signed, including those two countries combined “buying 77 percent of Colorado’s exports of ag and construction machinery in 2013.”

And, while data is difficult to gather, Colorado’s exports in services to NAFTA likely exceed our exports in goods.

Far from being an economic threat, free trade is a critical source of American wealth and jobs, benefiting consumers and workers alike. The real threat to Colorado and to the entire nation is the mindless, xenophobic trade-bashing being engaged in by both presidential candidates.

Ross Kaminsky is host of “The Ross Kaminsky Show” weekday mornings on 630 KHOW.

To send a letter to the editor about this article, submit online or check out our guidelines for how to submit by e-mail or mail.