They rightly revolted against the inconsistencies of Kant's third and fourth positions about the existence of unknown but postulated things in themselves, hidden from theoretical, but revealed to practical, reason.
Both philosophers appeal to the English love of experience, and Kant had these advantages over Hume: that within the narrow circle of sensible phenomena his theory of understanding gave to experience a fuller content, and that beyond phenomena, however inconsistently, his theory of reason postulated the reality of God, freedom and immortality.
Both these writers, more particularly the latter, had postulated in controverting Hobbes the existence of a moral sense to explain the fact that we approve benevolent actions, done either by ourselves or by others, which bring no advantage to ourselves.
Taking as types hydrogen, hydrochloric acid, water and ammonia, he postulated that all organic compounds were referable to these four forms: the hydrogen type included hydrocarbons, aldehydes and ketones; the hydrochloric acid type, the chlorides, bromides and iodides; the water type, the alcohols, ethers, monobasic acids, acid anhydrides, and the analogous sulphur compounds; and the ammonia type, the amines, acid-amides, and the analogous phosphorus and arsenic compounds.
In his ontology Xenocrates built upon Plato's foundations: that is to say, with Plato he postulated ideas or numbers to be the causes of nature's organic products, and derived these ideas or numbers from unity (which is active) and plurality (which is passive).
Anaximander postulated a corporeal substance intermediate between air and fire on the one hand, and between earth and water on the other hand.
Cuenot, in order to explain certain features in the hereditary transmission of coat colour in mice, postulated the hypothesis that the grey colour of the wild mouse (which is known to be a compound of black, chocolate and yellow pigments) may be due either to the interaction of a single ferment and three chromogens, or vice versa, to one chromogenic substance and three ferments.
For the world as a whole, however, he postulated a beginning in time (whence his use of the word creation), and further supposed that the impulse of organization which was conveyed to chaotic matter by the Creator issued from a central point in the infinite space spreading gradually outwards.
In thus reverting to the crudities of certain Pythagoreans, he laid himself open to the criticisms of Aristotle, who, in his Metaphysics, recognizing amongst contemporary Platonists three principal groups - (1) those who, like Plato, distinguished mathematical and ideal numbers; (2) those who, like Xenocrates, identified them; and (3) those who, like Speusippus, postulated mathematical numbers only - has much to say against the Xenocratean interpretation of the theory, and in particular points out that, if the ideas are numbers made up of arithmetical units, they not only cease to be principles, but also become subject to arithmetical operations.
Instead of the former divinely appointed aims of the Jewish, Greek, or Roman nations, which ancient historians regarded as representing the progress of humanity, modern history has postulated its own aims--the welfare of the French, German, or English people, or, in its highest abstraction, the welfare and civilization of humanity in general, by which is usually meant that of the peoples occupying a small northwesterly portion of a large continent.