In of World of Constant Opportunity Costs....

After grading the first homework of the semester semester, I thought I should take some time to clarify a bit about our old friend, opportunity costs. Most, I'm pleased to say, understood the concept (at least so far as the question is concerned). But most is not all.

Here's the question:

People often claim that hurricanes are good for the economy they affect because it creates a great deal of economic activity. While citing (and defining) opportunity costs, offer a challenge to this argument.

Opportunity cost occurs in two ways in these disaster scenarios: was the disaster economically beneficial and is it worth cleaning up?

The first question should always be answered with a no. If the disaster did not happen, infrastructure would still be intact and people would still have their lives and health. Thus resources spent to replace items or mitigate pain would instead be used to enrich an existing society. It's strictly better. Instead of losing a house and paying to rebuild it, you can keep the house and pay to expand on it (or buy a boat, or send a kid to college, or whatever).

The second question's answer is less certain. Perhaps it's not worth rebuilding. If a tornado destroys an obscure ancestral home and restoring it would benefit us by $1 million, but we could build a new school that would bring a benefit of $10 million, restoration is clearly not worth it even if we would be better off had not the building been destroyed. Just because it was worth having does not mean it is worth replacing.

People understand this distinction all the time. If a board game is destroyed in a flood, the family will certainly count it as a loss (having a game is better than not having one, all other things equal). But we wouldn't be surprised if they don't leap to replace it with the same game. They might buy a different game or buy something else entirely.

This distinction--the opportunity cost of a disaster and the opportunity cost of fixing--resolves the seeming paradox of why economists sometimes regret destruction while simultaneously refusing to repair damage. If we can stop disasters cheaply, that's great. But they are almost as unavoidable as opportunity costs and letting ruins stand is not always bad.