And accordingly it gave rise to the three great doctrines which divided the medieval schools: Realism of the Platonic type, embodied in the formula universalia ante rein; Realism of the Aristotelian type, universalia in re; and Nominalism, including Conceptualism, expressed by the phrase universalia post rem, and also claiming to be based upon the Peripatetic doctrine.
Erigena pronounces no express opinion upon the question which was even then beginning to occupy men's minds; but his Platonico-Christian theory of the Eternal Word as containing in Himself the exemplars of created things is equivalent to the assertion of universalia His whole system, indeed, is based upon the idea of the divine as the exclusively real, of which the world of individual existence is but the theophany; the special and the individual are immanent, therefore, in the general.
The author interprets Boetius's meaning to be " Quod eadem res individuum et species et genus est, et non esse universalia individuis quasi quoddam diversum."
But the Platonically conceived proof of the being of God contained in the Monologion shows that Anselm's doctrine of the universals as substances in things (universalia in re) was closely connected in his mind with the thought of the universalia ante rem, the exemplars of perfect goodness and truth and justice, by participation in which all earthly things are judged to possess these qualities.
The universalia in re have little place in his thoughts, which are directed by preference to the eternal exemplars as they exist in the supersensible world of the divine thought.
At the same time he has nothing to say against the Platonic theory of universalia ante rem (see Idealism).
Thus he defended the universalia ante rem as exemplars existent in the divine intelligence, and censured Aristotle's doctrine of the eternity of the world.
Finally, by abstraction from the individual things of sense, the mind is able to contemplate the universal apart from its accompaniments (animal sine homine, asino, et aliis speciebus); these subjective existences are the universalia post rem of the Nominalists and Conceptualists.
And in a similar spirit he explains the universalia ante rem as being, not substantial existences in God, but simply God's knowledge of things - a knowledge which is not of universals but of singulars, since these alone exist realiter.
Of this view the part which was not Aristotle's, the state of " universalia ante rem," was due to the Neoplatonists, who interpreted the " separate forms " of Plato to be ideas in intellect, and handed down their interpretation through St Augustine to the medieval Realists like Aquinas, who thus combined Neoplatonism with Aristotelianism.