Whately remarked that the reasoning of Euclid would have been disputed had it borne on the fortunes of individuals.
No matter the logic of the argument – no matter the consistency of the argument’s conclusions with human experience, both general and specific – no matter the scientific reputation and personal integrity of the scholars who advance the argument – if widespread acceptance of the argument threatens the power or the purses of members of some influential interest group or groups, the argument will not want for people, many with high reputations, to accuse it of being false, flawed, foolish, or the product of ideological corruption.
The case that free trade increases the material prosperity of ordinary people is as strong a case as is known in the social sciences. The truth of this case has been proved about as surely as any case about social reality can be proved. The arguments marshaled against the case for free trade are ridiculously weak; they are akin to someone arguing that Pythagoras’s reasoning and conclusions are mistaken or outdated because Pythagoras never drew a perfect triangle or that he never had access to a supercomputer. Every argument against a policy of free trade – every argument offered up by the mercantilists who wrote before Adam Smith’s time to the arguments barked by mercantilists today (including the assertions of bloviatingly ignorant and knavish politicians who, lusting for votes, pander to mercantilist interests and public ignorance) – has been heard by economists and answered conclusively thousands of times and in thousands of different ways. There is simply no credible economic case to be made that protectionism enriches the populace of the “protected” nation or region.
Yet because the case for free trade bears on the fortunes of individuals – because it bears on the fortunes of those particular individuals who currently are economically ascendant – the case for free trade has always been and will always be disputed in the interests of protecting the powerful both from the consequences of a widespread understanding of the truth and from the full freedom of their fellow citizens to pursue economic gain as they see fit.