Robert Mayer argues that certain kinds of high-interest payday loans should be legally prohibited. His reasoning is that such lending practices compel more solvent borrowers to cross-subsidize less solvent ones, and thus involve a kind of negative externality. But even if such cross-subsidization exists, I argue, this does not necessarily provide a ground for legal prohibition. Such behavior might be a necessary component of a competitive market that provides opportunities for mutually beneficial transactions to willing customers. And the alternative of (...) a government-mandated interest rate faces severe problems of its own. (shrink)