Necessary but not Sufficient

In my latest article for Libertarianism.org, I argue that the existence of a “market failure” is a necessary but not sufficient condition for government intervention in the economy.  A slice:

As with all economic questions, the answer is “compared to what?” Externalities, compared on an idealized hypothetical world where all information is known and transactions are costless, appear easy to solve via government regulation. However, when we compare a world of externalities to the real world, where costs and benefits are subjective and ultimately judgement calls must be made by analysts, we see that externalities are necessary but not sufficient justification for government intervention.