Noahpinion: Is trade really always efficient?: I'm a bit late to the party on Greg Mankiw's column about trade.... Mankiw's case for trade is the textbook one.... Trade is good because it is a voluntary exchange, and voluntary exchanges benefit the people who do them (or else they would not have chosen to carry out the exchange). Hence, trade liberalization is always good, Q.E.D.... [P]eople seem to agree (and agree with Mankiw) on one basic point: The efficiency of trade is not in question. Only the distributional effects of trade are in question. But to me, this seems highly non-obvious....
The question is: Since trade is a voluntary exchange,why would a country choose to trade if it were harming itself by doing so?
Answer #1: Externalities. As Angus so pithily points out, "People, the United States is not a person!" Trades are undertaken not by countries, but by individuals within those countries. Negative externalities, as every Econ 101 student knows, happen when an exchange between two people causes harm to a third. In the case of trade, the third person who is harmed may be in one of the countries that is engaging in trade.... [T]here would have to be some pretty big externalities for protectionism to actually be better than free trade in the aggregate. But certain types of trade could easily lead to reductions in overall economic efficiency. Unless every country could be persuaded to tax or otherwise mitigate the externality, liberalizing these types of trade could be a mistake, regardless of distributional effects.
Answer #2: Dynamic Inconsistency.... For most individual decisions, it seems unlikely that dynamic inconsistency outweighs the benefits of voluntary exchange. Addictive drugs are one of only a handful of plausible exceptions. But again, a country is not a person. A country's decision-making process may be far more prone to dynamic inconsistency than an individual's. This could throw a wrench into the "trade is always good" argument....
Notice that neither of these exceptions are arguments for autarky, or even for across-the-board trade restrictions. They are arguments that certain instances of trade liberalization may cause efficiency losses.
Mankiw does not address either of these theoretical possibilities. As far as he is concerned, the case for trade's efficiency is iron-clad in all cases.... I am against giving this sort of free pass. The supposed consensus that trade is always efficient to me smacks a bit of golden-age-ism and false consensus. You hear again and again that trade (or, at least, the efficiency aspect) is the one issue that economists have settled. But if a consensus exists, it is a result of politics and opinion, not because economic theories make an iron-clad case for the efficiency of trade. Theoretical exceptions do exist, and to ignore this fact (as we do) probably just makes people less trustful of economists in general.