Reflecting on the recent Democratic debate, Dan Henninger reports that Bernie Sanders said that he would fund his plan to make college free for students “through a tax on Wall Street speculation” (“Bernie Loves Hillary,” Oct. 15).

This statement reveals the frivolousness of Mr. Sanders’s economics. If such speculation is as economically destructive as Mr. Sanders regularly proclaims it to be, the tax on speculation should be set high enough to drastically reduce it.

But if — as Mr. Sanders presumably wishes — speculation is drastically reduced, very little will remain of it to be taxed and, thus, such a tax will not generate enough revenue to pay for Mr. Sanders’s scheme of making all public colleges and universities “tuition-free.”

That Mr. Sanders sees no conflict between using taxation to discourage (allegedly) harmful activities and using taxation as a source of revenue proves that he ponders with insufficient sobriety the economic matters on which he pontificates so sternly.

Excerpted from Cafe Hayek.