The porretaneans took oratio and significans seriously. Since the Porretaneans did not operate with significative orationes mentales, this means that propositions are vocal or written sentences. The most remarkable piece of doctrine concerning hypothetical propositions is that all arguments – syllogisms no less than enthymemes – are said to be hypothetical propositions, characterized by the use of the 'rational conjunction' ergo. Porretanean analysis of the enunciable corresponding to a syllogism, though there is a section in the Compendium about the dicta of conditionals and the source of their truth. Any medieval philosopher writing to explain what a genus-species hierarchy is all about will use the prototype of substance, corporeal substance, animal, man without too much concern about other substances, not to mention members of other categories. The Porretaneans' discussions of propositions, enunciables and truth demonstrate their method in the field of rationalis facultas.