Eifelheim - Michael Flynn [149]
“One does not debate nature; one experiences nature.”
“Oh, surely. But John Mirecourt—you will not have heard of him. They call him ‘White Monk.’ A Capuchin, as you might suppose. His propositions were condemned at Paris last year—no, it was in forty-seven—by which accolade we know him for a thinker of the first rank. He has shown that experience—evidentia naturalis—is an inferior sort of evidence.”
“Echoing Parmenides. But Albrecht said that in investigations of nature, experience is the only safe guide.”
“No. Experience is a poor guide, for tomorrow one may have a contrary experience. Only those propositions whose contrary reduces to a contradiction—evidentia potissima—can be held with certainty.” Ockham spread his hands to invite rebuttal.
Dietrich said, “A contradiction in terms is not the only sort of contradiction. I know that grass is green from experience. The contrary can be falsified by experientia operans.”
Ockham cupped his ear. “Your lips move, but I hear Buridan’s voice. Who can say but that, in some far-off place, one may not find yellow grass?”
Dietrich was brought short by his recollection that, in the Krenkish homeland, the grass was indeed yellow. He scowled, but said nothing.
Ockham pushed himself to his feet. “Come, let us proof your proposition with an experience. The world turns, you said.”
“I did not say that it did turn; only that, loquendo naturale, it might. The motion of the heavens would be the same in either case.”
“Then why seek a second explanation? Of what use would it be, even were it true?”
“Astronomy would be simplified. So, applying your own principle of the least hypothesis—”
Ockham laughed. “Ah. Argument by flattery! A more potent argument by far. But I never intended entities in nature. God cannot be bound by simplicity and may choose to make some things simple and others complex. My razor applies only to the workings of the mind.” He was already striding toward the door and Dietrich scurried to catch up.
Outside, Ockham studied the indigo sky. “Which way is east? Very well. Let us apply experience. Now, if I move my hand rapidly, thus, I feel the air pushing against it. So, if we are moving toward the east, I should feel an east wind on my face, and I—” He closed his eyes, and spread his arms. ”—feel no wind.”
Joachim, climbing Church Hill, stopped in the path and gaped at the scholar, who seemed to have adopted the attitude of the Crucified.
Ockham turned toward the Lesser Wood. “Now, if I face north …” He shrugged. “I feel no change in the wind whichever direction I face.” He paused expectantly.
“One must arrange the experience,” Dietrich insisted, “so that all matters affecting the conclusion are accounted for, which Bacon called experientia perfectum.”
Ockham spread his hands. “Ah, so the common senses are insufficient for this special sort of experience.” Grinning as if he had triumphed in a quodlibet, he returned to the parsonage, Dietrich again in his wake. Joachim, following, latched the door and went to the pot for a stein of ale. He sat at the table beside Dietrich and tore a piece of bread off the loaf and listened with a smirk.
Dietrich pressed the argument. “Buridan considered the objections to a turning earth in his twenty-second Question on the heavens, and found a response for each, save one. If the entire world moves, including earth, water, air, and fire, we would no more feel a resisting wind than a boat drifting with the current feels the motion of the river. The one compelling objection was that an arrow loosed straight up does not fall west of the archer, which it would if the earth were turning underneath it, for an arrow moves so swiftly that it cuts through the air and thus would not be carried along by it.”
“And this Oresme has resolved the objection?”
“Doch. Consider the arrow at rest. It does not move. Therefore, it begins already with the motion of the earth and, when loosed, possesses two motions: a rectilinear motion up and down, and a circular motion toward the east. Master Buridan wrote that a body impressed with motion,