In a column earlier this week, I looked to Ronald Reagan for the arguments for free trade, and how far U.S. President Donald Trump has departed from them. To which his supporters would likely reply: “Finally! Reagan was wrong then and wrong now, or perhaps right then, but his policy is wrong now.”

This is not an unreasonable argument and needs to be engaged, even if the manner of implementation is idiosyncratic. It is important to understand the policy’s rationale, against the background of our own history.