Mark Montgomery is the Donald L. Wilson Professor of Enterprise and Leadership and Professor of Economics at Grinnell College. The opinions expressed in this commentary are his own.

I'm a registered Democrat in Iowa, where I have taught economics for more than 40 years. About once a week, some Democratic candidate campaigning for the fast-approaching caucuses shows up at a coffee shop or restaurant in my little prairie town seeking the support of me and my neighbors. Every couple of days, I get a text or a phone call from the local staff of Bernie, Cory or Mayor Pete, asking who I will caucus for in February.

For me, all this attention from the Democrats conjures up some uncomfortable questions: Am I really a Democrat, or just pretending to be one? Can I, as an economist, focus on the things that I like about the Democratic hopefuls, and ignore the things that bother me?

Take Trump's tariffs, for example. Why don't the candidates all propose to scupper the tariffs? Trump's trade war makes investors reluctant to invest because they create an uncertain business climate. As an economist, I know that shrinking investment is a recipe for recession. The new president could eliminate the tariffs on the first day on the job. Yet no one standing on the debate stage seemed eager to suggest this.

Why not? One reason is that labor unions traditionally favor protective tariffs since they want to boost American manufacturing, and Democrats traditionally avoid irritating labor unions. Unionized workers have tended to support the Democratic party.

The actual impact of tariffs is widely misunderstood by the general population. Trump calls the trade deficit with China a form of theft, and many Americans agree that China has been engaging in unfair trade practices. Economists, on the other hand, see it more like a gift — if China sends us shirts, shoes and semiconductors in exchange for money, which they then loan back to us by buying Treasury bills, why don't we consider that a good deal? If the Chinese government were to stop buying up the dollars and loaning them to us, that would indeed help American producers, but it would impose higher prices of imports on American consumers.

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