I’ve been getting a fair bit of correspondence wondering why I haven’t written about the negotiations for a Trans Pacific Partnership, which many of my correspondents and commenters regard as something both immense and sinister.

The answer is that I’ve been having a hard time figuring out why this deal is especially important.

The usual rhetoric — from supporters and opponents alike — stresses the size of the economies involved: hundreds of millions of people! 40 percent of global output! But that tells you nothing much. After all, the Iceland-China free trade agreement created a free trade zone with 1.36 billion people!!! But only 300,000 of those people live in Iceland, and nobody considers the agreement a big deal.

The big talk about TPP isn’t that silly. But my starting point for things like this is that most conventional barriers to trade — tariffs, import quotas, and so on — are already quite low, so that it’s hard to get big effects out of lowering them still further.

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