“Putnam argues that coherence, plausibility, and simplicity are values, i.e. epistemic values, and that these values are presupposed in scientific inquiry*.* But if the fact/value dichotomy is true, then along with ethical and aesthetic values, epistemic values too must be subjective and untestable. As Putnam writes, “every argument that has ever been offered for noncognitivism in ethics applies immediately and without the slightest change to these epistemological predicates” (Realism, p.138). Thus, the dichotomist is committed to regarding disagreements over epistemic values as merely personal and subjective. With the water boiling example, when people disagree on which revision is more plausible, the dichotomist must hold that each is just expressing their subjective preferences. In short, upholders of the fact/value dichotomy are committed to giving up scientific objectivity completely. Scientific objectivity and ethical objectivity stand or fall together.”
This analysis is true. Epistemology is value laden but not necessarily normative. Epistemological positions IE Occam’s Razor can be both descriptive and prescriptive. Putnam’s analysis is true in that universal prescriptivism in epistemology is incoherent, as it is in ethics.
Unfortunately, his reductio ad absurdum is not actually absurd. He is simply deriving a conclusion from a set of premises, seeing that the conclusion makes him uncomfortable or is incompatible with his current beliefs and thinks he has made a persuasive argument. I guess an obvious question would be ‘why is “abandoning” scientific objectivity absurd (and was it ever there in the first place)?’.
edit: Before I am misunderstood, I would not say that epistemic values are ‘merely preferences’; It would be more accurate to say that Occam priors describe how humans form beliefs and make decisions under conditions of uncertainty. I think that all humans share similar priors. I also think that almost all humans share certain fundamental moral beliefs. In neither case does this make the beliefs true in the sense Putnam wishes them to be.