Eli Dourado wrote this on Twitter:

Despair. RT @GovChristie: The State Division of Consumer Affairs will look closely at any and all complaints about alleged price gouging.

When there’s a natural disaster some people, like Gov. Christie, start complaining in knee-jerk fashion about price gouging. And then some other people, with their knees jerking in exactly the same fashion, start complaining about people who complain about price gouging. The latter sets of knees usually belong to economists.

Suppose that an unexpected shock has occurred which has two effects. First, it increases demand for, say bottled water. Second, it cuts off supply lines so that in the short-run the quantity of bottled water in the relevant location is fixed at Q. A basic principle of economics is that if you wish to maximize total surplus then you should allow the price to adjust to its market-clearing level. This ensures that those Q consumers with the highest value for water get it. The total surplus will then be the sum of all their values.

The price plays two roles in this process, one crucial to the result, one just incidental and not necessarily intended. First, it separates out the high-value consumers from the low-value consumers. That’s the crucial role. Unavoidably it also plays a second role of taking some of that total surplus away from the consumers and giving it to producers. If you are maximizing total surplus you are completely indifferent to that second effect.

But what if you don’t want to maximize total surplus but just want to maximize consumers’ surplus? Your goal is that the Q bottles of water you’ve got should generate the greatest possible benefit for those who will consume them. I would bet that most people who understand the previous paragraph also assume that it applies equally well to the problem of maximizing consumer’s surplus. How else would you maximize it but to ensure that those with the highest value get the water?

But in fact it is quite typical for the consumer surplus maximizing solution to be a rationing system with a price below market clearing. I devoted a series of posts to this point last year. The basic idea is that the efficiency gains you get from separating the high-values from the low-values can be more than offset by the high prices necessary to achieve that and the corresponding loss of consumer surplus.

Why would we only care about consumers’ surplus and not also the surplus that goes to producers? We normally we care about producer’s surplus because that’s what gives producers an incentive to produce in the first place.  But remember that a natural disaster has occurred. It wasn’t expected. Production already happened. Whatever we decide to do when that unexpected event occurs will have no effect on production decisions. We get a freebie chance to maximize consumer’s surplus without negative incentive effects on producers. And just at the time when we really care about the surplus of bottled water consumers!

Of course there are other good reasons to be skeptical of rationing in practice. It might not be enforceable, it might lead to inefficient rent-seeking, etc. But these objections mean that the debate should be about rationing in practice. The theoretical argument against it is weaker than many people think.