Abstract

Dietrich of Freiberg (c. 1240/1250-1318/1320) was an important representative of the Dominican order in the Middle Ages. He focused on central philosophical problems taken up toward finding solutions applicable for philosophy as well as theology and the natural sciences. Methodologically, rational argumentation was key for

Dietrich, even as he aimed, in line with Augustine’s recommendation, at a concordance between authority (auctoritas) and reason (ratio). Characteristic of his thought are his theory of intellect, whose cognition renders it self-knowing knowledge: consciousness as self-consciousness; his doctrine of what is an essentially structured cosmos reflecting the comprehensible rationality of its absolute principle, the Godhead; and his theory of the rainbow. Dietrich was particularly influenced by Albert the Great, while he himself influenced the Proclus commentator Berthold of Moosburg.

Originally from Saxony, Dietrich of Freiberg (c. 1240/ 1250-1318/1320) was a member of the Dominican order who served as its Provincial Superior for the province of Germany from 1293 to 1296, as well as being its Vicar General from 1294 to 1296. In 1296/1297 in Paris, Dietrich obtained his master’s degree in theology (magister in theologia), teaching there for about two years. In 1310, he was commissioned to lead the order as its Vicar Provincial. Dietrich probably died c. 1318/1320.

The bulk of his writings Dietrich devoted to specific philosophical problems. From the start, he considered intellect to be the central topic of philosophical investigation. In his treatise, On the Origin of Categorially Determined Reality (De origine rerum praedicamentalium), Dietrich explores the relation between nature - after God, the intelligences (intelligentiae. immaterial forms), the spiritual substances and the heavenly bodies, the sublunary sphere dependent on these - and intellect. While Henry of Ghent asserted that intellect is affected by natural objects, Dietrich took the opposite view: intellect constitutes the essential being, the quiddity (‘‘whatness’’), of the natural object and in this quiddity the very ‘‘what’’ (quid) itself of the object. This he holds because the natural object cannot distinguish between itself as ‘‘what’’ it is and its ‘‘whatness,’’ or essence, nor can it in turn combine these so differentiated components. Intellect alone is able to do this. Intellect is not passive, but rather active, since it is intellect which through the process of definition provides the natural object its essence. Indeed, Dietrich ascribes to intellect the function of efficient cause (causa efficiens): Its very differentiation (between the components of the natural object as the object of cognition) is its efficacy, for it effects the definition and through the definition renders the natural object cognizable as something, as ‘‘what’’ it is. For intellect, it is only in this way that the object even becomes an object at all - as a unity of ‘‘whatness’’ and ‘‘what,’’ both constituted by intellect. Cognition of an object therefore means, ‘‘intellect effects its definition,’’ differentiating through the definition the ‘‘whatness’’ from the ‘‘what’’ and, at the same time, combining the ‘‘whatness’’ and the ‘‘what.’’

Nonetheless, intellect is also passive, inasmuch as the cognizing possible intellect presupposes the activity of the agent intellect, for the possible intellect grasps its objects by conceiving this very activity. Indeed, the agent intellect is also an efficient cause (causa efficiens). In itself, in an intuitive act, the agent intellect cognizes: its principle, God, itself, and the universe of beings. In the possible intellect, however, the agent intellect effects the general contents (species intelligibiles) cognized by the possible intellect in cognizing the agent intellect, and the possible intellect cognizes the agent intellect only in cognizing these general contents. Exclusively in the state of bliss (in beata vita) is the agent intellect not merely efficient cause, but also formal cause, when it is unified as a form with the possible intellect as a kind of matter - that is how man essentially cognizes God, according to Dietrich in his treatise On the Beatific Vision (De visione beatifica). All this illustrates the way in which Dietrich tends to proceed, drawing theologically important conclusions from philosophically justified presuppositions. Such presuppositions rest methodologically on rational argumentation concording, as much as possible, with arguments of authority. Even so, for Dietrich, reason takes precedence before authority.

Authority for the view that the possible intellect in its cognizing enjoys general cognition is provided by Aristotle with his theory of science. Thus, Dietrich concludes his treatise On the Intellect and the Content of Cognition (De intellectu et intelligibili) by enumerating the features that an object must have in order to be an object of scientific cognition. What is important is that it has being, that it has general validity and necessity, and that the fundamental grounds for cognizing something are provided, hence that the elements of definition are given. Cognition, insofar as it is knowledge, cannot change; for change transforms cognition into non-cognition - on this premise Plato, Aristotle, and Dietrich all agree.

Intellect which knows that it knows and knows what it knows is for Dietrich ‘‘being’’ which conceives and which in conceiving conceives its object; such intellect is, at the same time, being which conceives itself as its object and therein is conscious conception, consciousness as self-consciousness, ens conceptionale inquantum huiusmodi. In this view, sense perception and imagination are conceptional beings (entia conceptionalia). The intellectual object alone is the same as its conception; solely for intellect is its conception intellect itself - is intellect itself its own object. Hence, intellect is consciousness of itself.

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In his philosophy of nature, Dietrich treats such topics as continua, contraries, and optical phenomena. One continuum is time, which for Dietrich possesses merely intramental being, a view combining the philosophies of time developed by Aristotle, Augustine, and Averroes. Dietrich differs from Aristotle to the extent that he situates contrariety only in the third kind of quality, which includes passive qualities and affections, no longer allying it with four categories. This reflects his consistent aim of reducing the principles of nature.

Dietrich’s place in the history of science is assured by his work On the Rainbow (De iride), with its theory perfected only centuries later by Descartes and Newton. While most of his predecessors compared the colors of the rainbow to the spectrum issuing from the sun’s rays on passing through a water flask, tending to equate the latter with a cloud or a collection of drops, Dietrich was the first to trace the light’s path through the individual drop, discovering two refractions at the surface of the drop nearer the observer and one internal reflection at the surface farther away. So explaining the primary, or lower, rainbow, Dietrich elucidated the production of the secondary, or upper, rainbow as involving two refractions at the surface of the drop nearer the observer and two internal reflections at the surface farther away - thus accounting for the color inversion in the secondary rainbow.

See also: > Albert the Great > Berthold of Moosburg > Consciousness > Epistemology