The summit of Grecian philosophy bears the name of Aristotle. He was a practical man who did not like to stray into the distance when he could find good things near by, and he did not concern himself about the descent of understanding. Its platonic origin from an ideal world went instinctively against his grain. He, therefore, took hold of the question at the nearest end and analyzed the positive knowledge available at that time. But since Grecian science and the knowledge of Aristotlean times were rather slim, his attempt to demonstrate logic did not produce any decisive results. But it had been discovered that it was possible to make positive deductions from fixed premises.
Aristotle clung to this. He showed clearly and definitely, excellently and substantially, how logical deductions should be made in order to arrive at positive understanding. All dogs are watchful. My pug-dog is a dog, therefore it is watchful. What can be more evident? Why, then, speculate about God, freedom, and immortality, when indubitable knowledge may be obtained by the formal method of exact deductions?
But Aristotle had overlooked something, or, being a practical man, perhaps overlooked it intentionally. The premise from which he deducted the watchfulness of dogs in general, was handed down by tradition and had been accepted on faith. But was it founded on fact? Could there not be some dogs who lacked the quality of watchfulness, and might not our pug-dog be very unreliable, in spite of all exact deductions? In the case of the pug-dog this would not be of very great moment. But what about the question of the beginning and end of the world, or the question of the existence of God? The Grecian gods had been outgrown by Aristotle.
The history of logic, and of philosophy in general, is interrupted by Christianity and by the decline of the antique world, until the reformation opens a new era. The Catholic church had, in its own way, thoroughly settled the great questions of the true nature of things, of beginning and end, reason and consequence. But when it, and with it Christianity, began to disintegrate, disbelief once more posed in the brains of the philosophers the old question: How do we obtain reliable and true understanding? Reliability and truth were at that time still identical.
Bacon and Descartes are the men who started the investigation. Both of them were disgusted with Aristotle and with his formal logic, particularly with the subtleties of scholasticism. It did not satisfy this new epoch to found positive understanding on traditional contentions and exact deductions therefrom. It is a radical epoch and, therefore, epoch-making. The new philosophers have the aim of unequivocal understanding in common with the ancient philosophers. Bacon still connects himself with the stock in trade of the past. His historian says of him that one should not reiterate that Bacon took his departure from experience, for this means nothing or nothing more than that Columbus was a mariner while the main thing is that he discovered America.... He wanted to find a new logic corresponding to the new life.... The inventive human mind has created the new time, the compass, the powder, the art of typography.... He wanted a new logic which corresponded to the spirit of invention. He, the philosopher of invention, was Lord Chancellor of England, was a man of the world. Not only himself, but also his science, was too ambitious, too full of energy, too world-embracing, for him to bury himself in solitude. That is a glory for a philosopher, but at the same time an obstacle for his special task, for the new logic. He recognized the import of his task only in its general outlines. But his contemporary and successor Descartes approached the matter more radically and pointedly.
Although in recent times the human mind had demonstrated its positive faculty of understanding in natural sciences, especially by inventions, still it was prejudiced by religious improbabilities in its great premises dealing with the essence of things and men, with the "good, true, and beautiful," as the ancients called it. In order to end his doubts, Descartes elevates radical doubt to the position of a principle and of a starting point for all understanding. Then he cannot doubt that he is at least searching for truth. He who does not believe in any understanding, any science, any inventions, cannot doubt at all events that the impulse for understanding is there. It, at least, is undeniable. Cogito, ergo sum—I think, therefore I am—that is a premise which cannot be shaken. The rest, thinks Descartes, may be deducted by Aristotlean methods.
With this thought, the philosopher of modern times relapsed into the old error that anything positively true could be ascertained with logical formulas. His consciousness of the thoughts stirring in his brain, I might say his flesh and blood, convinced him by matter-of-fact evidence of the reality of their existence.
This fact had hitherto been misunderstood. It is claimed that Descartes could convince himself only of the existence of his soul, of his thought, by evidence. No, my feeling, my sight, my hearing, etc., are just as evident to me as my thinking, and simultaneously with sight and hearing that which is heard and seen. The separation of subject and object can and must be merely a formality.
The Descartian thesis has been distorted into the statement that nothing is evident to man but his own subjective conception. And the ideology has been carried to the extreme of calling the whole world an idea, a phantasmagoria. True, Descartes needed God in order to be sure that his conceptions did not cheat him.
In order to prove that we no longer need such extravagant means in our times, I shall devote another chapter to this subject.