Reason is, and ought only to be, the slave of the passions

… and can never pretend to any other office than to serve and obey them," declared philospher David Hume in A Treatise on Human Nature. In The New Yorker, John Cassidy, writing about the implications of neuroeconomics, argues, "If emotional responses often trump reason, there can be no presumption that people act in their own best interest." Cassidy's solution? Good old-fashioned paternalism.

The Cato Institute's resident philosopher, Will Wilkinson, shows in this outstanding article that Cassidy misunderstands what neuroeconomics is really telling us about human rationality and liberty. Just one point here: Cassidy seems to assume that people are more "rational" in picking their politicians than they are in choosing between desserts.

As Wilkinson correctly notes, this is highly implausible:

If you really think people make systematic "mistakes" in judgment and choice, there is no reason to believe that democratic voters—who have less at stake when casting their ballots than when choosing what to have for lunch—will be especially good at populating the government with Spock-like rational legislators interested in tweaking cognition through expertly targeted policy rather than with well-coiffed primates interested in hoarding status and power.

It turns out that Hume got it basically right more than 250 years ago.