 Thus, e.g., whereas there was no need to appeal to caloric at some prior or deeper level, with design, according to various design advocates, there is still an explanatory lacuna (or implicit promissory note) requiring reference to design at some explanatory level prior to Darwinian evolution. Indeed, as some see it (and as Paley himself suggested), there are phenomena requiring explanation in design terms which cannot be explained away at any prior explanatory level (short of the ultimate level).