In a sense intervening between Aquinas and Siger of Brabant was Boethius of Dacia. A colleague of Siger at Paris, he would later meet a similar exile upon the Condemnation of 1277, although his later biography is unclear. Boethius’ mid 1270s treatise, yet another installment in the De Aeternitate Mundi genere, differs markedly from the treatment of Siger, inasmuch as it makes explicit the implications of the position for the scope of philosophy’s truth-claims. At the very onset of his work, Boethius straddles philosophy and theology with corresponding obligations: one must assent to demands of revelation, in necessary, without rational justification, to avoid heresy; similarly, one must submit to reason in reference to things which are not self-evident but do admit of rational explanation, for to do otherwise would be to be unphilosophic. (34) For Boethius, unphilosophic is perhaps the key word: more than anyone else in Europe, he was target of 1277’s lead proposition, having maintained in his treatise De Summo Bono that philosophic life represented the highest natural good of man.
Within this context, however, he shares neither Siger’s bald disregard for the implications of the quaestio, nor Aquinas’ politically hesitant skepticism (or sagacity?). Instead, recognizing the co-dependency of theology and philosophy, he seeks an alliance of mutual advantage,
so that faith’s position may be more firmly maintained, even though in certain cases it cannot be demonstrated, lest otherwise we fall into foolishness by seeking demonstration where such is not possible; or into heresy by refusing to believe that which should be held on faith and which cannot be demonstrated. (35)
Having set forth his aims, Boethius then proceeds to lay out the typical arguments against the eternity of the world, starting from the argument that the world must come after its first principle in duration. He then runs through ten more arguments, emphasizing that creation is not identical with mere generation, and noting a sort of ontological argument in that the totality of time and motion are subject to addition, by category, and are therefore not eternal. Then the philosopher reverses his course and raises a series of arguments for the eternity of the world, aiming to demonstrate that it can be eternal. Heading the list is, as one would expect, Siger’s argument that effects may be simultaneous with their causes in duration. From this, issue several arguments in favor of eternal particular effects. Boethius now shift to arguments that world actually is eternal, starting with in argument that the world is incorruptible because it is not generated, and generally recapitulating Siger’s arguments in brief, especially emphasizing that a primary will, mover, or agent is eternal and must have some eternal effect coeternal with its action. (36)
After rehearsing counter-objections to these arguments, which he now excuses as the potential arguments of heretics, Boethius proceeds to advance upon a solution. In the first place, he insists that philosophy ought to employ reason towards whatever may be grasped by human reason: “it belongs to the philosopher to determine every sort of question which can be disputed by reason; for every question which can be disputed by rational argument falls within some part of being,” which is the province of philosophical investigation. (37) Secondarily, he asserts that the philosopher cannot show by rational arguments that the first motion and the world came to be.” The philosopher, as a natural scientist, is categorically constrained by the limits of his own science: “one skilled in a given science may prove, concede, or deny something only in terms of the principles of his own science.” (38) Furthermore, the natural world is the first principle accessible to philosophy: “although nature is not the first principle in the absolute sense, nonetheless it is the first principle in the realm of natural things.” (39) The upshot of this is that the natural philosopher altogether unable to consider creation:
For nature produces its every effect from a subject and from matter. But production from a subject and matter is generation, not creation. Therefore the natural philosopher is unable to study creation. . . . Since the making of the world and its production in beings cannot be generation, as is evident, it follows that in no part of natural science will the making of the world or its production in being be taught for production is not natural and therefore does not pertain to the natural philosopher. (40)
Boethius thus speaks in two radically different categories as philosopher and Christian. However, the natural scientist is able to be informed of the possible existence of higher causes, and ought not to assert or to deny them on the basis of reason or natural philosophy. (41)
Does Boethius beg to break the law of non-contradiction? In his sharpest articulation: “one may say . . . both that the world and the first motion began to be and that the natural philosopher speaks the truth when he denies that the world and the first motion began to be.” (42) Again, this formulation looks exactly like impassable “double-truth,” until we remember that unbreakable category distinctions render it non-contradictory. Thus, when Boethius announces that “clearly there is no contradiction between Christian faith and philosophy concerning the eternity of the world,” he may immediately proceed “to prove that what is contrary to the truth, that is, that the world is coeternal.” (43) He develops his refutations of all of those arguments originally raised to demonstrate that the world is eternal, quite in terms of higher supernatural causes, emphasizing the will and personality of God as known through revelation. In sum, “When someone puts aside rational arguments, he immediately ceases to be a philosopher; philosophy does not rest on revelations and miracles.” (44) From this perspective, Condemnation no. 90 seems grossly unfair. “That the natural philosopher should deny without qualification that world began to be since he bases himself upon natural causes; but the believer can deny the eternity of the world because he bases himself on supernatural causes.” (45)
In contemporary parlance, the “philosopher” of Siger and (especially) Boethius is our “hard” scientist. Their stuggles to come to terms with the relations of natural and supernatural causation are still very revelant for us as modern citzens of a technocratic age. Against the mounting imperialism of neo-Darwinian biology , quantum physics, and astrophysics, which regularly leave useful hypotheses and indulge in the highest orders of metaphysical speculation, Boethius and Aquinas remind us that it is possible to use natural philosophy and scientific knowledge without confuting the Christian Gospel. Aristotle and his sons would seek to demand a halt to infinite regresses, but only out of convenience: infinite regresses invoke an infinite God. Similarly, modern philosophers of nature are left staring at the unverifiable phenomena-savers in the form of black holes and sub-atomic physics, looking at the metaphysical limits of matter. In particular, the sort of hard category distinctions erected by Boethius provide an exemplary model for meaningful interaction between science and faith today: We know God’s act of creation through our senses, and act upon this through our reason, but we cannot thereby know God as he is in himself, apart from revelation.