On Bananas, Fish, and Trade

Commenting on this blog post, Warren Platts writes:

If imports were stopped by a stroke of a pen, there would still be a trillion dollars of pent up demand per year from American consumers. If the demand for goods couldn’t be satisfied with imports, domestic manufacturers would take up the slack, creating jobs. Things would be more expensive, sure, but the GDP would grow a lot faster, more people would have good jobs.

Warren’s argument, while common, is incorrect.  Imports, which do satisfy demand, generate more demand for other products by virtue of the fact they are of lower economic cost.  As Warren says, if these imports were stopped, “things would be more expensive.”  This inherently means that there are not “trillions of dollars in pent up demand per year,”that American manufacturers can simply “take up the slack.”  Rather, those trillions of dollars are released by the imports and would become constrained by the forbidding of such.

By way of example, let’s say we have two countries: Bananaland and Fisherland. In autarky (that is, no trade), Bananaland can produce 50 fish or 50 bananas.  Fisherland can produce 100 bananas or 200 fish.  If each country divides their time evenly between each activity, Bananaland can produce and consume 25 bananas and 25 fish.  Fisherland can produce and consume 50 bananas and 100 fish.  In this autarky, the price of bananas in terms of fish is 1 in Bananaland and .5 in Fisherland (in other words, Bananaland needs to give up 1 fish to produce 1 banana.  Fisherland need only give up half a banana to produce 1 fish). The two countries open trade with one other and, given that both countries want to consume the same number of bananas after trade as before (an assumption made for simplicity; doesn’t change the story if we relax this), then the citizens of Bananaland agree to send 25 bananas for 37 fish (a price of .68).  To satisfy this, Bananaland stops producing fish and produces only bananas (they produce 50 bananas).  Fisherland cuts back on banana production to 25 but ramps up fish production to 150.  The day comes and the two trade.  Now, Bananaland consumes 25 bananas and 37 fish.  Fisherland consumes 50 bananas and 113 fish.  Their total economic well-being (crudely called “GDP”) is Bananaland: 62 (25+37) and Fisherland: 163 (50+113).

Bananaland, convinced their getting a bad deal following the lack of fishing in their country (remember, what was once a thriving industry) and the low prices they now pay, elect a protectionist on the grounds that he (and he alone) will “Make Bananaland Great Again!”  He promptly forbids all imports of fish from Fisherland.  They go back to their autarky ways.  Since Bananalanders now pay higher prices for their fish and more resources are devoted there than elsewhere, they can only consume 25 fish and 25 bananas.  Their GDP falls to 50!*  There was “pent up demand,” but the higher costs the various citizens now have to pay to even just consume the same amount they did before eats up that “pent up demand.”  The domestic manufacturing simply cannot supply it.

Adam Smith first explored this concept way back in 1776, and David Ricardo formalized it with the theory of Comparative Advantage.  Trade occurs for the simple reason that it provides people with better outcomes than other alternatives.  Other alternatives simply cannot provide the desired outcomes.

Update: I realized, as reading though this, I made a small math error.  It has been corrected.

*It’s worth nothing a similar decline happens to Fisherland, a nation where they can produce much higher levels than Bananaland.  Their GDP falls to 150.  Even their manufacturing cannot satisfy the “pent up demand.”