A taxonomy of slippery slope arguments

Eugene Volokh has recently objected to my post deriding the sorts of “slippery slope” arguments invoked in the “same-sex marriage” debate. His post inspired me to take another look at my two very favorite pieces on slippery slope arguments – Fred Schauer’s 1985 piece and Gene’s own much longer 2003 piece (both in Harvard). They are both terrific articles, and they inspire me to generate my own taxonomy of legitimate “slippery slope” arguments, to demonstrate (in order of importance) that (a) I can coin nifty alliterative phrases that will catch on in the blogosphere; (b) I’ve got no hard feelings against Brian Leiter whom I think is an eminently fair-minded, unnervingly prolific guy; (c) slippery slope arguments are generally misplaced in the context of same-sex marriage; and (d) Fred’s account of the slippery slope more accurately captures the spirit of the metaphor than Gene’s.

The essence of the slippery slope is a metaphor about a mountain: The peak of the mountain is stable, the sides are unstable (“slippery”), and bottom of the slope is bad. (If you are an acrophobic non-skier like me, think the top of the ski lift with a jump at the end of the slope). Even if the slope is just as good (or bad) a place to be as the peak, one should stay off those slippery slopes to avoid sliding into a place that is worse than both the peak or the slope – the bottom. To capture the metaphor, therefore, one needs to identify arguments in which a move from peak (P) to slope (S) is attacked despite the apparent harmlessness of S because, once one re-locates to S, one will be inexorably sent to the bottom (B), where S is closer to, but more desirable than, B.

With this definition in mind (which differs from Gene’s in one respect that I’ll clarify after the jump), here’s my taxonomy of legitimate slippery slope arguments:

(1) The Calculated Creep: A vague rule is proposed with desirable applications – but the opponent states that (a) the relevant decision-maker will deviously exploit the vagueness to extend the rule in undesirable ways and (b) no one can come up with a well-crafted amendment to arrest the creep towards the undesirable applications.

(2) The Subtle Sorites: A rule is proposed with desirable applications that requires judgments of matters of degree – that’s the "sorites" -- but the opponent of the rule states that (a) the well-intentioned decision-maker will be unable to determine when the rule has been taken too far and (b) no one can come up with a well-crafted amendment to arrest the creep towards the undesirable applications.

(3) The Recondite Reductio: A rule is proposed that has a rationale with both desirable and undesirable implications – but the opponent states that (a) the well-intentioned decision-maker will not likely distinguish the desirable implications from the “absurdum” and (b) no one can come up with a well-crafted amendment to prevent the absurdum.

Here’s an illustration of all three modes of argument.

Rick: I loathe protests against University's admittedly dumb decisions about honorary degree awardees at festive celebrations of communal unity like graduation ceremonies. These ceremonies should be a DMZ free of the usual political fracas.

Brian: Really? You’d even look askance at a protest of David Duke, the KKK guy?

Rick: Well, uh, I guess that I’d approve of protests against handing out degrees to truly bigoted knuckleheads with no genuine achievement like Duke.

Brian: Great! We’re all going to go to Wash. U. to protest Phyllis Schlafly’s getting a degree. Wanna come? She’s said a lot of mean things about feminism, immigrants, gays, and (gasp) natural selection. Alan Wolfe panned her biography. Get in the van.

Rick: Schlafly?! Gee – she’s sort of close to the line, isn’t she? I mean is she truly a Bigoted Knucklehead? I only want to protest true BKs, for sake of preserving that festive communal atmosphere, etc. Half of the Republicans in the House have probably said all of the dumb things that Schlafly has said. She has not put on a white robe with a pointy top or marched around with swastika like Duke, right? And, unlike Duke, she has a JD and has been one of the most effective political organizers in the 1970s and 1980s – important enough to earn a laudatory biography published by Princeton Press, even if some reviewer that you cite panned it.

Brian: Those are all terrible, rotten, really bad arguments! You just said that you’d allow protests against Duke – and the differences between Duke and Schlafly are just matters of degree (the subtle sorites/calculated creep), so protesting Schlafly follows directly from your own premises (the recondite reductio).

Rick: OK. I’ve had enough. We need a bright-line social norm condemning all graduation protests of honorary degree awardees. The President and Board of an accredited college would never approve a true BK like David Duke, and, once we condone and approve protests against folks like Schlafly, we will be drawn into protests against any person with controversial views and dubious intellectual eminence. It is a slippery slope….

Brian: You are a knucklehead.

Rick: You’re intolerant.

(Just for the record: Brian never called me a knucklehead, I did hint that he might be intolerant, and nothing he wrote about me even came close to crossing any “civility” line. Moreover, his smacking me on his blog earned me envy from all of my Philosophy prawf buddies who said that they had always wanted to be smacked on the biggest philosophy blog in the biz. So thanks, Brian).

In my little dialogue above, “Rick” properly invoked the Slippery Slope. But opponents of same-sex marriage cannot do so. There is no sorites: Same-sex marriage is itself a bright-line category that does not include polygamy, etc. Moreover, the rationale for same-sex marriage is that same-sex couples are indistinguishable from heterosexual couples, except that they cannot procreate with each other. Hard to see any recondite reductio there that will ineluctably draw us into polygamous, polyandrous, bestial, or other couplings.

Gene Volokh has a broader definition of “slippery slope” arguments and thus reaches a different conclusion about the applicability of such arguments to same-sex marriage. He defines slippery slope arguments in his '03 piece to “cover[] all situations where decision A, which you might find appealing, ends up materially increasing the probability that others will bring about decision B, which you oppose.” He urges that it does not matter “whether or not you think that A and B are on a continuum where B is in some sense more of A, a condition that would in any event be hard to define precisely.”

I think that Gene’s broad definition loses the essence of the metaphor. His definition, for instance, would apply to any opposition to a “killer amendment” based on the strategic fear that the amendment, even if inherently desirable, would defeat one’s most preferred position. The locus classicus of such amendments is Representative Howard Smith’s proposal to add gender to Title VII – a move intended to defeat the prohibition on racial discrimination and opposed as such by many liberals who approved of bans on gender- and race- discrimination, because they believed that the amendment would doom the latter. It would be an odd use of language, I think, to object to Smith’s amendment on the ground that it would create a slippery slope towards no prohibition on racial discrimination – but Gene’s definition of slippery slope arguments would allow just such an inappropriate use of the phrase.

In short, the essence of the slippery slope is the inability to come up with an amendment that will constrain decision-makers, either because language or the decision-makers are imperfect. Schauer’s account captures this essence better than Gene’s – although Gene’s article has truly wonderful illustrations on how multi-peaked preferences might scare a legislator silly. But that’s a story for another post.