A few months ago, Julian and Will both observed that Ralph Waldo Emerson’s famous quotation, “A foolish consistency is the hobgoblin of small minds,” has been the victim of a gross misinterpretation. Emerson was not defending the holding of contradictory views at the same time; rather, he was defending the virtue of being willing to change one’s mind, rather than forcing one’s present views to be consistent with what one said in the past. As Julian notes, self-contradiction is hardly a virtue: “The notion that there's something wrong with consistency within one's own views at a given time—the idea, in other words, that you should just arbitrarily apply a principle in some cases but not in others, is pretty bizarre, and I can't think of anything to recommend it.”
It occurs to me, however, that while consistency-within-time is the greater virtue in philosophical matters, consistency-over-time is often the greater virtue in law and public policy. One of the fundamental principles of the rule of law is that individuals should be able to predict how the law will apply to their specific cases, both in the present and the future. The ability of people to predict the rules gives them a greater capacity to plan their lives, form commitments, make investments, and coordinate their behavior with others. Of course, this doesn’t mean the rules can never change; indeed, it is desirable for people to know that the law will sometimes change in ways that take account of new circumstances. But in general, there is value to having a degree of constancy in the rules to facilitate individual planning.
As my one-time dissertation advisor (and now coauthor) Mario Rizzo has pointed out, there is a difference between logical consistency and praxeological consistency. (He drew this distinction partially from Mises, but I don’t think Mises was especially clear on the subject.) Policies that are praxeologically consistent are those that people can rely on for purposes of choosing their behavior; it can also mean policies that minimize interpersonal conflict and allow people to coordinate their actions. Policies that are logically inconsistent might nonetheless be praxeologically consistent. For instance, the doctrines of tort law might be justified on normative grounds that are foreign to property or contract law. And yet as long as the resulting rules are sufficiently clear and predictable, they can provide the basis for intelligent planning by individuals. Changing one of the rules might make the two branches of law more consistent with each other, but less consistent with what has gone before – possibly botching people’s plans in the process.
Take, for example, the recent trend in tort law toward holding people liable for the self-regarding choices of others – e.g., the possibility of holding McDonald’s liable for the obesity of its customers. Obviously, the underlying principle here is that individuals cannot be held totally responsible for their own actions. Fortunately, this notion has not yet taken firm hold – the McDonald’s suit hasn’t succeeded yet (though it still might, and there are plenty of other examples in tort law of people getting compensated for harms brought on by their own poor judgment). But let’s suppose that it eventually does take hold. We might still be spared a horrendous legal outcome by the fact that contract law has been somewhat more resistant to anti-responsibility norms. A contract like this one pointed out by Amy, in which restaurant customers sign a waiver before consuming a sinful dessert, would still be upheld in court. As a result, the law would be logically inconsistent but praxeologically consistent: customers and restaurants could still make their transactions with a reasonable ability to predict the outcome. But then suppose that contract law were forced to become consistent with tort law. Restaurant owners might suddenly find themselves liable for numerous activities (like serving desserts to waiver-signing customers) that they had thought would be just fine. If they had known how the law would change, perhaps they and their customers would have behaved differently. Worse, the change in the contract law could create a plethora of unintended consequences in other endeavors where waivers are involved: bungee-jumping, medical procedures, and so on. For a time, at least, turmoil would reign.
On the other hand, plenty of policy examples demonstrate the importance of consistency-within-time relative to consistency-over-time. The S&L debacle is a nice example of a case in which it would have been better to adopt any consistent policy (either FSLIC plus extensive investment regulation, or no FSLIC and minimal investment regulation) instead of the inconsistent policy we did choose (which allowed S&L’s to keep over-risky investment portfolios and stick the taxpayer with the tab when their investments turned south). Moral hazard is just one possible result of inconsistent policies existing simultaneously.
My question, then, is whether there is some principle for choosing between consistency-over-time and consistency-within-time. Is there a weighing process? Or should one always outweigh the other whenever they conflict?