CHAPTER XXXV
CLASSIFICATION OF TOPICS; STAGES OF EVOLUTION
I. Philosophic Classification of the Sciences; the Arrangement
of Vincent’s Encyclopaedia, of the Lombard’s Sentences, of
Aquinas’s Summa theologiae.
II. The Stages of Development: Grammar, Logic, Metalogics.
I
Having considered the spirit, the field, and the dual method, of mediaeval thought, there remain its classifications of topics. The problem of classification presented itself to Gerbert as one involved in the rational study of the ancient material.[431] But as scholasticism culminated in the twelfth and thirteenth centuries, the problem became one of arrangement and presentation of the mass of knowledge and argument which the Middle Ages had at length made their own, and were prepared to re-express. This ordering was influenced by a twofold principle of classification; for, as abundantly shown by Aquinas,[432] theology in which all is ordered with reference to God, will properly follow an arrangement of topics quite unsuitable to the natural or human sciences, which treat of things with respect to themselves. But the mediaeval practice was more confused than the theory; because the interest in human knowledge was apt to be touched by motives sounding in the need of divine salvation; and speculation could not free itself of the moving principles of Christian theology. On the other hand, an enormous quantity of human dialectic, and a prodigious mass of what strikes us as profane information, or misinformation, was carried into the mediaeval Summa, and still more into those encyclopaedias, which attempted to include all knowledge, and still were influenced in their aim by a religious purpose.[433]
As the human sciences came from the pagan antique, the accepted classifications of them naturally were taken from Greek philosophy. They followed either the so-called Platonic division, into Physics, Ethics, and Logic,[434] or the Aristotelian division of philosophy into theoretical and practical. The former scheme, of which it is not certain that Plato was the author, passed on through the Stoic and Epicurean systems of philosophy, was recognized by the Church Fathers, and received Augustine’s approval. It was made known to the Middle Ages through Cassiodorus, Isidore, Alcuin, Rabanus, Eriugena and others.
Nevertheless the Aristotelian division of philosophy into theoretical and practical was destined to prevail. It was introduced to the western Middle Ages through Boëthius’s Commentary on Porphyry’s Isagoge,[435] and adopted by Gerbert; later it passed over through translations of Arabic writings. It was accepted by Hugo of St. Victor, by Albertus Magnus and by Thomas, to mention only the greatest names; and was set forth in detail with explanation and comment in a number of treatises, such as Gundissalinus’s De divisione philosophiae, and Hugo of St. Victor’s Eruditio didascalica,[436] which were formal and schematic introductions to the study of philosophy and its various branches.
The usual subdivisions of these two general parts of philosophy were as follows. Theoretica (or Theorica) was divided into (1) Physics, or scientia naturalis, (2) Mathematics, and (3) Metaphysics or Theology, or divina scientia, as it might be called. Physics and Mathematics were again divided into more special sciences. Practica was divided commonly into Ethics, Economics, Politics, or into Ethics and Artes mechanicae. There was a difference of opinion as to what to do with Logic. It had, to be sure, its position in the current Trivium, along with grammar and rhetoric. But this was merely current, and might not approve itself on deeper reflection. Gundissalinus speaks of three propaedeutic sciences, the scientiae eloquentiae, grammar, poetics, and rhetoric, and then puts Logic after them as a scientia media between these primary educational matters and philosophy, i.e. the whole range of knowledge, theoretical and practical. Again, over against philosophia realis, which contains both the theoretica (or speculativa) and the practica, Thomas Aquinas sets the philosophia rationalis, or logic; and Richard Kilwardby opposes logica, the scientia rationalis, to practica, in his division.[437]
The last-named philosopher was the pupil and then the hostile critic of Aquinas, and also became Archbishop of Canterbury. He was the author of a careful and elaborate classification of the parts of philosophy, entitled De ortu et divisione philosophiae.[438] In it, following the broad distinction between res divinae and res humanae, Kilwardby divides philosophy into speculativa and practica. Speculativa is divided into naturalis (physics), mathematica, and divina (metaphysics). He does not divide the first and third of these; but he divides mathematica into those sciences which treat of quantity in continuity and separation respectively (quantitas continua and quantitas discreta). The former embrace geometry, astronomy and astrology, and perspective; the latter, music and arithmetic. Practica, which is concerned with res humanae, is divided into activa and sermocinalis: because res humanae consist either of operationes or locutiones. The activa embraces Ethics and mechanics; the scientia sermocinalis embraces grammar, logic, and rhetoric. Such are Kilwardby’s bare captions; his treatise lengthily treats of the interrelations of these various branches of knowledge.