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At this point the mainstream economist pushes back. He doesn’t deny (How could he?!) that, as a technical matter, getting precise information on marginal social costs is practically impossible. But he insists that such an ideal standard is inappropriate. “We can estimate the divergence between private and social costs closely enough,” the mainstream economist assures us, “and then have government act on those estimates. It’s better than doing nothing.”
While it’s true that the perfect should never be allowed to obstruct the good, there are at least two looming problems with this mainstream-economics approach – problems that warn against trusting it to serve as a reliable guide to government policy.
First, as explained above, there’s no good reason to think that estimates made of social costs by even well-intentioned and sparklingly brilliant government officials will be close-enough to accurate to trust that a government empowered to correct market failures will, on the whole, raise social welfare. The assumption that such officials will typically perform well enough on this front is based on no science; it’s merely an assumption – or, rather, an aspiration.
Second, there’s no good reason to think that government officials in reality face incentives that prompt them to behave as their doppelgängers in textbooks behave. The entire case for using government to correct alleged market failures is built on the belief that self-interested actions of private decision-makers lead them to seek private benefits at the greater expense of the public. But if we assume that people act self-interestedly in their private spheres we must make the same assumption about people’s motivations in public spheres.
Yet despite more than a half-century of warnings from public-choice economists, mainstream economists continue to assume, without much apparent thought, that government officials act in a way that is categorically different from the way these same persons would act were they in the private sector: private persons are assumed to act to promote their own self-interests, while government officials are assumed to act to promote the public interest.
What, however, could be more unscientific than this assumption of dual motivations? It is justified neither by science nor by common sense, but it is crucial to the “scientific” case for government action to correct market failures.
My argument is not that markets are perfect. (They certainly are not.) Nor is my argument that a highly informed and well-meaning deity could not intervene in markets in ways that improve their performance. (Such a splendid creature certainly could.) My argument is that because economists advise government officials rather than deities, the economic case for using government to correct market failures is scientific only in the most superficial sense. Deep down it’s mostly superstition.