Cass Sunstein and Richard Thaler’s notion of “Libertarian Paternalism” has already occasioned plenty of blogospheric debate, but their recent LA Times op-ed has reopened the floodgates. Jonah Goldberg has a crop of posts, and Jim Manzi and Will Wilkinson also take shots. I’ve been at least somewhat more open to the idea than some of my fellow travelers in the past—many of the objections I saw in previous go rounds amounted to complaints that Sunstein & Thaler weren’t using “libertarian” to mean “strictly in accordance with Rothbardian side-constraints.”

That said, I think Will makes the best case I’ve yet seen against the idea—at least to the extent that the authors are calling for an enforcable public policy, rather than simply recommending a practice for private firms. He writes:

Sunstein and Thaler may wish to design the presentation of choices to bias decisions in favor of, say, happiness. But other choice architects may be more interested in biasing our choices toward virtue or toward participation in great collective projects. Obviously everyone is a “choice architect” to some degree in his or her daily intercourse with others. And some people, like marketers and salespeople, try to shape choices for a living. The thing is, we often rightly resent their attempts to manipulate us, but at least we are more or less in control of our exposure to such people. But when choice architecture is implemented politically, we cannot opt out of these attempts at manipulation, attempts which may or may not be benign. That’s a big problem because political choice architecture may do a great deal to shape us, even if, in its “libertarian paternalist” incarnation, it makes a show of leaving the ultimate choice open to individuals.

For example, I would object if President John McCain implemented a policy of opt-out national service because such a policy would communicate all-too-clearly that individuals need some kind of special justification or rationale not to serve the state. The default rule itself contains meaningful content. If allowed to stand, such a policy could shape norms and individual preferences in a direction antagonistic to the value of autonomy. Soon enough we might find ourselves asking, “Why should you be able to opt out at all?” The paternalistic nudge may “leave the choice open” but accepting the legitimacy of the certain nudges may imperil liberty.

And, of course, there are varying degrees of “nudges,” as Manzi points out. You can make the “opt-out” procedures so burdensome or costly that it’s functionally indistinguishable from a ban. (From a certain perspective, after all, fines and prison terms are just very high opt-out costs.) The only thing that restrains me from joining in a full-throated rejection of the notion is that given our growing tolerance of all sorts of paternalism, I worry that in many cases the alternative is just full-blown old-fashioned paternalism. In other words, I’m pretty sure there’s a slippery slope here, but I’m not sure which direction it tilts in.

I would very much rather see the national conversation shift in such a way that the self-appointed guardians of public health and welfare feel themselves compelled to talk about ways to encourage people to make “better” choices while respecting their autonomy, instead of plowing ahead on the assumption that once we know the “right’ decision, we should mandate it. I would obviously be dismayed if the upshot of this was to concede that it’s valid to “shape” people’s decisions, with the only remaining debate concerning the strength of the “nudge”. There’s always the possibility that, precisely to the extent that people exercise their autonomy by opting out, our soi-disant guardians will infer that we need yet more vigorous “shaping”. At this point, the new paternalism bleeds into the old sort because the appropriate “nudge” is one just strong enough to yield only trivial noncompliance with the guardians’ notion of what’s best. The key, for this to be made attractive to actual libertarians, would be to precommit to the idea of low, fixed opt-out costs, rather than allowing the optimal cost to be a function of the level of compliance produced.