My good friend Harry Pollard may have overstated his case that "Trade
(referring to free trade) has been normal throughout the history of Man".
Maybe it should have been, but for better or worse, international exchange
controls and trade monopolies have been more normal, I believe. A. Smith
called it "mercantilism". Before that there were taxes and controls between
provinces and principalities and city-states. Turgot pioneered in getting
them lowered or removed in France, and his thinking helped inspire the U.S.
Founding Fathers to put the commerce clause in our Constitution. Within
city-states there were controls over trade with their contado's or
hinterlands.
Unilateral free trade was a British innovation, 1846-1914 approximately,
briefly copied by Prussia and France. As an earlier contributor (Neill?) to
this HES service noted, it is unusual to be able to generalize from here and
now to everywhere and forever.
Mason Gaffney