Republican presidential candidate Donald Trump and Speaker Paul Ryan disagree on a number of issues. One of the most divisive of these is trade. Trump has misdiagnosed the situation, being guilty of the post hoc ergo propter hoc fallacy: If A comes before B, then A caused B. It is true that the North American Free Trade Agreement was followed by American jobs moving abroad.

NAFTA came into effect on Jan. 1, 1994. For that month the United States trade deficit was $6,207 million. By January 2016 it was $42,308 million, roughly seven times greater. But that does not mean that NAFTA was the cause and job loss the effect. Even with the most poorly negotiated trade deals, other things equal, exports equal imports, and there is no balance of trade deficit. But other things are not equal.