Reply to Ellis
The illuminating essay by Brian Ellis views the project of Hypothetical Reasoning. in the light of the perspective afforded by the important distinction between truth-conditions. and acceptability-conditions. (or “assertability conditions,” as I myself prefer to call them).1 Historically, it was not quite this distinction that underlay my book, but a couple of related, older ones, viz. the distinction between formal and material facts, and the cognate distinction between the modus operandi. of logic and of epistemology. The logician looks to entailment relations: he does not tell one categorically “Such-and-such substantive theses are true” but only hypothetically “If you accept such and such substantive theses as true, then you must (in all due circumstances) accept certain others as true.” What concerns him is the relative. and not the absolute. truth of substantive contentions. The epistemologist, on the other hand, does concern himself with the latter issue via the question “Under what sorts of conditions and circumstances is there adequate rational warrant for claiming the truth of certain substantive theses?” The approach of Hypothetical Reasoning. was intended to be of the latter sort, and its question was that of providing a “rational reconstruction” of the epistemological processes that issue in our classing certain counterfactual conditionals as true or warranted and rejecting others as false or unwarranted. Its concern was not with the logician’s issue of truth-relationships., but with the epistemologist’s issue of a criterion for truth-attributions..