I think my law students understood my first-class example about contracts, incentives and hot water. But Kevin Drum, Matt Yglesias and others are having some difficulties. No problem. I will make it simpler. Suppose we have a law that says that at the end of every year landlords must rebate their tenants $50 for every month of rent paid. Good for tenants, right? Perhaps in the very short run but in the near future we can expect to see rents rise by $50 per month and the old equilibrium will be restored in all essentials. Now suppose that instead of being required to rebate the $50 the landlords are required to spend the money on shoes for the tenants. Now both tenants and landlords are almost certainly worse off since the tenants would almost certainly have used the rebate to buy something other than shoes. The hot water example hardly differs.
Of course, we could add in some other features that might make the law a good idea. Suppose, for example, that hot water encourages bathing which reduces the transmission of disease. Tenants won’t take the external benefit of hot water into account and thus hot water will be underprovided – a hot water requirement or better yet a subsidy might be justified in this situation.
An alternative explanation for laws like this is that they are supported by people who want to keep the poor out of their neighborhood – this is an externality argument also but one quite different from that above. Whatever the explanation, note that these arguments are quite different than the naive one which assumes that the requirement transfers wealth from the landlord to the tenant. Contracts are multi-dimensional, force one part to change and the others will adjust. More bonus points: What implications does this have for the study of price controls?
As I told my students, understanding the basic analysis is the first-step on the path to wisdom, it is not the end of the path. But you have to understand the first step if you are going to reach the final destination.