The first point:

The syllogism in question yields knowledge only through a universal affirmative proposition. Every syllogism must therefore contain an established, comprehensive universal proposition. This, too, is acknowledged and agreed upon.

Hence their statement: “No syllogism can be formed from two negative premises or from two particular premises.” Accordingly, universal truths—comprehensive statements—must constitute the starting points of syllogisms and proofs, and the foundations on which they are built and upon which they depend.

They further state that the starting points of demonstrative syllogisms consist of certain knowledge: internal and external sensory perceptions, rational truths, self-evident truths, mass-transmitted reports, and findings established through experience. Some also add intuitive truths.

Yet neither internal nor external sensory perceptions contain universal propositions, since internal and external sensation apprehend only particular things, which are established only when the reporter has perceived through the senses what he reports; they are therefore dependent on sensory perceptions. Likewise, experience concerns only particular, perceptible things. The intellect judges similar cases by comparing them, which is reasoning by analogy. Intuitive truths—according to those among them who recognize them—are of the same kind as findings established through experience.

The difference, however, is that experience involves the experimenter’s own actions, as with foods, drinks, and medicines