 So far, we have looked at public goods mainly as economic goods that have certain characteristics that give rise to doubts whether they can be provided privately at efficient levels. The government might be justified in engaging in the production of a public good because it corrects a market failure. Such an argument will always be contingent on private actors’ inability to produce the good or enough of it, which is why mechanisms that encourage private provision have been examined at some length in  Section 4  above.