You’ll have to excuse my ignorance here, whereas you have a doctorate in philosophy (I think) I’m just a Wandering Internet Commentator whose experience with philosophy extends no farther than a 101 college class.
I’m very close to the doctorate but not quite there yet—check back in a few months…
So if you wouldn’t mind me asking, just what is the difference between an empirical argument and a normative argument, and why should we consider the latter having as much merit as the former, or even any merit at all?
There is not space right here to do a full accounting of either metaethics or logic, but suffice it to say, we all live to some great extent submitting to the strength of good norms and rejecting bad proposed norms. We all understand the normative force of the need to give reasons for our beliefs and for our actions and the right to demand reasons for both from others, at least insofar as they affect us.
Even asking me “why should normative arguments have merit” you in practice demand of me a normative argument in order to justify my position. You want me to tell you why you should accept normative arguments. You must already accept that normative arguments have merit if you are even going to listen to consider my reply adequate or inadequate! If you reject my reasoning based on rational judgment of my reasons, having been open to rational reasons and been closed to irrational ones, then you were implicitly already understanding the difference between normative arguments that have merit and ones that do not and tacitly applying that standard to what I say.
We are already engaged in the practice of reasoning. Insofar as you evaluate arguments rationally and think you do so defensibly because you employ reasons, you acknowledge the force of norms (rational norms) and accept them. If you are irrational and reject rational norms, what good is it to me to try to reason with you since, in your irrationality you do not accept reasons grounded in truth-conducive sources to be normative in the first place.
So, either you accept that reason provides us with certain logical intuitions, that the senses provide us with generally reliable sources of knowledge and evidence, etc. and that reason requires that we judge all our disputable notions to correct any errors they may contain, or you do not. If you do so, you understand and accept the force of epistemic norms. If you do not, then it is hopeless for me to appeal to reasons since you irrationally refuse to acknowledge their normative force, opting to think (and supposedly live as far as is possible) in contradiction with yourself, rather than according to reasons.