Practical conditionals are a problem. We all use conditionals like, “If you want a great steak, you ought to go to Manny’s Steak House.” But suppose I do want a great steak; does it follow that I ought to go to Manny’s? No—maybe my doctor has told me to lay off the red meat. Then is the conditional false? That doesn’t seem right either, if Manny’s really is the best place for a great steak.
We can put a sharper point on this problem. Suppose your best friend’s wife is very attractive, attractive enough to put ideas in your head. (Readers of other persuasions will have to generate their own example.) But suppose also that you think sleeping with one’s best friend’s wife is morally repugnant. Consider the two claims, both plausible in their own way:
(A) If you want to seduce your best friend’s wife, you ought to spend a lot of time alone with her.
(B) If you want to seduce your best friend’s wife, you ought not spend a lot of time alone with her.*
Add the premise that you want to seduce your best friend’s wife, and we have two parallel modus ponens arguments, one of which concludes that you ought, and the other that you ought not, spend a lot of time alone with her.
Clearly, both these arguments can’t be sound while there is no equivocation. So here are the options as I see them:
- It’s impossible for both conditionals to be true. This just seems wrong; there can be cases where, on some reading of each conditional, both are true.
- The arguments have different structures, so one is valid and the other is not. This is probably the standard view: the claim is that (A) is Ought( you want to seduce à you spend time alone) while (B) is You want to seduce à Ought not( you spend time alone). Jamie Dreier has a paper attempting to debunk this theory. In any case, I’ll ignore it for now.
- There’s an equivocation somewhere. Since the contents of the desires and oughts don’t matter, nor the person to whom the conditional is addressed (you, me, or Jones), the only candidates here are
3a. an equivocation on ‘ought’. Maybe (A) contains a subjective ought and (B) contains an objective ought. One problem here is that the consequents of (A) and (B) can be replaced by imperatives: “…spend time alone!” “…don’t spend time alone!” and while both conditional imperatives seem reasonable in their different ways, the ‘ought’ is not around anymore to blame the conflict on.
3b. an equivocation on ‘want’. This is the possibility that attracts me and which, so far as I know, is unexplored by anyone else. I’ll be interested to see what others think.
Here’s my main reason for being attracted to the idea of an equivocation on ‘want’. Many conditionals, including (A) and (B) I think, encapsulate arguments or lines of reasoning. From “If P, then Q” we can usually get, “P, therefore Q.” But if we try this on (A) and (B), we see that the lines of reasoning being employed are quite different. (A) encapsulates an instrumentalist inference: Here is an end you have, so you ought to take the most effective means to that end. The inference behind (B) is not instrumentalist. And what I would argue is that the starting points of these two inferences are different.
Instrumentalist inferences reason from desires or intentions to more desires or intentions. The premise(-state) is of the same type as the conclusion(-state). Whereas the inference encapsulated in (B) is reasoning from a belief about one’s desires. If I can invent some formalism, the difference between the two lines of reasoning is
[Des] I seduce my best friend’s wife
[Des] I spend time alone with her.
[Bel] I want to seduce my best friend’s wife
[Des] I don’t spend time alone with her.
So my claim is that the antecedent “you want to seduce your best friend’s wife” in (B) above is exactly what it seems, a description of a desire. But in (A), it’s the expression of a desire. That’s why the modus ponens argument using (B) goes through, but the one using (A) does not.
(Q: Er, where did the ‘ought’ go? Shouldn’t the conclusions of these inferences be, “[Bel] I ought (/not) spend time alone with her”? A: Um, yes. Short version of my semantics of ‘ought’: those [Bel] conclusions will be true just in case the [Des] conclusions are correct, in a sense of ‘correct’ to be specified. Work with me here, and concentrate on the premises!)
Here’s another argument for equivocation on ‘want’: we sometimes use ‘want’ this way in other contexts. "If you’re going to Kenosha, you want to take the highway." This is obviously not saying that facts about your desires follow from facts about your destination. The encapsulated inference is
[Des] I go to Kenosha
[Des] I take the highway,
not anything concluding in
[Bel] I want to take the highway.
So again, “you want to take the highway” in the consequent of the conditional is expressing a desire, not describing one.
* I was first turned on to this kind of example by Michael Huemer, in a much earlier thread. His example was so revolting that I couldn’t concentrate on it for any length of time, so I’ve changed it in this post.