Well, I’ll acknowledge that you could change premise 2 into an inference rule. But notice that you could change either premise 2—the pro-desire-satisfaction one and the pro-desire-frustration one—into an inference rule. Indeed, you could change any normative claim into an inference rule: you could change “people who want to have gay sex ought to go see a trained Baptist minister to get cured” into an inference rule, and then validly go from “I want to have gay sex” to “I ought to go see a trained Baptist minister to get cured”. So from the fact that premise 2 could be changed into an inference rule, I don’t think anything follows that might jeopardize its status as a full-blooded normative claim.
On the second point, I thought lukeprog was discussing direct conceptual reduction. But if he wants to provide hypothetical imperatives with a synthetic reduction, he’ll need a theory of reference capable of explaining why the normative claim turns out to make reference to (and have its truth-conditions provided by) simple causal facts. And on this score, I think hypothetical imperatives and categorical moral imperatives are on an equal footing: since reductionist moral realists have a hard time with synthetic reductions, I would expect reductionist ‘instrumental realists’ to have a hard time as well.
Perhaps so, but then the normativity stems from premise 1, leaving premise 2 as non-normative as ever. But the question is whether premise 2 could be a plausible reduction basis for normative claims.
Well, I’ll acknowledge that you could change premise 2 into an inference rule. But notice that you could change either premise 2—the pro-desire-satisfaction one and the pro-desire-frustration one—into an inference rule. Indeed, you could change any normative claim into an inference rule: you could change “people who want to have gay sex ought to go see a trained Baptist minister to get cured” into an inference rule, and then validly go from “I want to have gay sex” to “I ought to go see a trained Baptist minister to get cured”. So from the fact that premise 2 could be changed into an inference rule, I don’t think anything follows that might jeopardize its status as a full-blooded normative claim.
On the second point, I thought lukeprog was discussing direct conceptual reduction. But if he wants to provide hypothetical imperatives with a synthetic reduction, he’ll need a theory of reference capable of explaining why the normative claim turns out to make reference to (and have its truth-conditions provided by) simple causal facts. And on this score, I think hypothetical imperatives and categorical moral imperatives are on an equal footing: since reductionist moral realists have a hard time with synthetic reductions, I would expect reductionist ‘instrumental realists’ to have a hard time as well.
For what it’s worth, I think what’s really being inferred by the advice-giver is:
1 Granting your (advisee’s) starting point, you ought to lose weight.
2 Less calorie consumption and more calorie burning leads to weight loss.
3 Therefore you ought to consume less and burn more calories.
The advisee’s desire portrays the starting-point as a truth.
Perhaps so, but then the normativity stems from premise 1, leaving premise 2 as non-normative as ever. But the question is whether premise 2 could be a plausible reduction basis for normative claims.