At first blush, the mercantilists' call for "free trade but fair trade" sounds reasonable. After all, who can be against fairness? Giving the idea just a bit of thought suggests that fairness as a guide for public policy lays the groundwork for tyranny. You say, "Williams, I've never heard anything so farfetched! Explain yourself."
Think about the First Amendment to our Constitution that reads: Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."
How many of us would prefer that the Founders had written the First Amendment so as to focus on fairness rather than freedom and instead wrote: Congress shall make no unfair laws respecting an establishment of religion, or prohibiting the fair exercise thereof; or abridging the fairness of speech, or of the press; or the right of the people to peaceably assemble in a fair fashion, and to fairly petition the Government for a redress of grievances"?
How supportive would you be to a person who argued that he was for free religion but fair religion, or he was for free speech but fair speech? Would you be supportive of government efforts to limit unfair religion and unfair speech? How might life look under a regime of fairness of religion, speech and the press?
Suppose a newspaper published a statement like "President Obama might easily end his term alongside Jimmy Carter as one of America's worse presidents." Some people might consider that fair speech while other people denounce it as unfair speech. What to do? A tribunal would have to be formed to decide on the fairness or unfairness of the statement. It goes without saying that the political makeup of the tribunal would be a matter of controversy. Once such a tribunal was set up, how much generalized agreement would there be on what it decreed? And, if deemed unfair speech, what should the penalties be?