Richard Thaler really dislikes it when conservatives argue that if it is constitutional to require all people to purchase health insurance, it must be constitutional to require them to buy broccoli too. But he doesn’t have any good counterarguments. In the New York Times, he characterizes the conservative claim as a kind of slippery-slope argument. He doesn’t explain why this particular slippery-slope argument is, in his view, wrong; he just says that it could be explained. (“Surely, the justices have the conceptual resources to draw a distinction between the health care market and the market for broccoli. And even if they don’t, then all the briefs, the zillions of blog posts and a generation’s worth of economic literature can help them.”) Nor does he make a strong argument against slippery-slope arguments in general. How could he? It’s impossible to deny that any claim of the form “accepting A makes it much more likely that we will eventually get B,” where A is controversial but everyone rejects B, could ever be true.
And the conservative argument Thaler is attacking doesn’t take that form anyway! I re-read the column to check, and it seems as though Thaler really believes that conservatives who make this argument about Obamacare are making a “forecast” that the insurance mandate will lead to a broccoli mandate. “Can anyone imagine Congress passing a broccoli mandate law, much less the court allowing it to take effect?” But that’s not what Justice Scalia, whom Thaler quotes but doesn’t understand, was getting at. His point — and the point of the vast majority of conservatives who have brought up the broccoli-mandate hypothetical — pertains to constitutional logic, not the future course of history. Conservatives are saying, first, that any reading of the Constitution that authorizes Congress to mandate the purchase of insurance must also authorize it to mandate the purchase of broccoli and, second, that the idea that the Constitution authorizes Congress to mandate broccoli purchases seems so wrong as to discredit that reading. Everyone understands this. Or so I would have thought before reading Thaler’s article.