The De Interpretatione opens with a reference to this psychological distinction, implying that names represent conceptions, propositions represent combinations of conceptions.
Moreover we can make a history of Aristotle's thought and gradual composition thus: (s) Earlier acceptance in the De Interpretatione of Plato's grammatical analysis of the sentence into noun and verb (secundi adjacentis) but gradually disengaging the proposition, and after wards introducing the verb of being as a third thing added (tertium adjacens) to the predicated verb, for the purpose of opposition.
The different works are more or less connected by a system of references, which give rise to difficulties, especially when they are cross-references: for example, the Analytics and Topics quote one another: so do the Physics and the Metaphysics; the De Vita and De Respiratione and the De Partibus Animalium; this latter treatise and the De Animalium Incessu; the De Interpretatione and the De Anima.
This important difference between the De Interpretatione and the Prior Analytics can only be explained by supposing that the former is the earlier treatise.
Moreover, the arrangement sometimes breaks down: for example, though on the whole the logical books are quoted without quoting the rest, the De Interpretatione (chap. 1) quotes the De Anima, and therefore is falsely taken by Zeller against its own internal evidence to be subsequent to it and consequently to the other logical books.
Beside the theological and political works above quoted, Occam wrote Summa Logices (Paris, 1488, Oxford, 1675) commentaries on Porphyry's Isagoge, on the Categoriae, De Interpretatione and Elenchi of Aristotle.
We cannot write a history of the varied origin of logic, beyond putting the rudimentary logic of the proposition in the De Interpretatione before the less rudimentary theory of categories as significant names capable of becoming predicates in the Categories, and before the maturer analysis of the syllogism in the Analytics.
Secondly, he made no division of logic. In the Categories he distinguished names and propositions for the sake of the classification of names; in the De Interpretatione he distinguished nouns and verbs from sentences with a view to the enunciative sentence: in the Analytics he analysed the syllogism into premisses and premisses into terms and copula, for the purpose of syllogism.
Commentary on Aristotle's De Interpretatione crept vetas), ed.
He got so far as gradually to write short discourses and long treatises, which we, not he, now arrange in the order of the Categories or names; the De Interpretatione on propositions; the Analytics, Prior on syllogism, Posterior on scientific syllogism; the Topics on dialectical syllogism; the Sophistici Elenchi on eristical or sophistical syllogism; and, except that he had hardly a logic of induction, he covered the ground.