Legal Commentary

The California Supreme Court's recent decision on gay marriage has predictably revived that old perennial favorite of arguments against substantive due process arguments for sexual privacy -- the "slippery slope."

You know the drill: If courts strike down x law regulating sexual conduct, then it will be logically impossible to avoid striking down y, z, a, b, and c laws. That latter set usually involves references to laws prohibiting bestiality, polygamy, and public nudity. But Justice Scalia, warming to his theme in his Lawrence v Evans dissent, added invalidation of laws against "masturbation" to the usual series (539 U.S. 558, 590). (I did a double take when I saw that new marcher in the parade of horribles: Since when did any states have laws against masturbation?)

The obvious response to the "slippery slope" is the "conceptual ledge": There are lots of natural resting places for the mind, if one only bothers to look for some fine-grained moral/legal theory. Public nudity is, well, publicly visible; bestiality does not foster emotionally important human sociability; polygamy thrives on subordination of women; and so forth. Of course, such theories require courts/legislatures to pick and choose on the aspects of human sexuality that they think are worth protecting from the law and those that are not -- but that's hardly news.

So why do patently unconvincing slippery slope arguments grow like black mold in a leaky attic every time a court makes a decision about sexuality? I think that we've used slippery slope arguments so carelessly that we are losing our intellectual capacity to draw fine-grained conceptual distinctions. Once one starts invoking the essential similarity of one thing to another, one can't stop: The temptation to assert foolishly that logical consistency requires elision of any distinction not crudely cut with a meat cleaver becomes an addictive habit. (E.g., "You think animals have rights? Why don't you let them vote?" "You think invading Iraq was a good idea? Why not China?" And so forth).

Maybe we should just swear off "slippery slope" arguments entirely to avoid sliding into such conceptual incoherence. After all, once you start, you can't stop: It's a slippery slope....