It is a fact placed forever beyond doubt, say the modern psychologists, that every perception received by the mind is determined by certain general laws which govern the mind; is moulded, so to speak, in certain types preexisting in our understanding, and which constitutes its original condition. Hence, say they, if the mind has no innate ideas, it has at least innate forms. Thus, for example, every phenomenon is of necessity conceived by us as happening in time and space—that compels us to infer a cause of its occurrence; everything which exists implies the ideas of substance, mode, relation, number, etc.; in a word, we form no idea which is not related to some one of the general principles of reason, independent of which nothing exists.
These axioms of the understanding, add the psychologists, these fundamental types, by which all our judgments and ideas are inevitably shaped, and which our sensations serve only to illuminate, are known in the schools as categories. Their primordial existence in the mind is today demonstrated; they need only to be systematized and catalogued. Aristotle recognized ten; Kant increased the number to fifteen; M. Cousin has reduced it to three, to two, to one; and the indisputable glory of this professor will be due to the fact that, if he has not discovered the true theory of categories, he has, at least, seen more clearly than anyone else the vast importance of this question—the greatest and perhaps the only one with which metaphysics has to deal.
I confess that I disbelieve in the innateness, not only of ideas, but also of forms or laws of our understanding; and I hold the metaphysics of Reid and Kant to be still farther removed from the truth than that of Aristotle. However, as I do not wish to enter here into a discussion of the mind, a task which would demand much labor and be of no interest to the public, I shall admit the hypothesis that our most general and most necessary ideas—such as time, space, substance, and cause—exist originally in the mind; or, at least, are derived immediately from its constitution.
But it is a psychological fact none the less true, and one to which the philosophers have paid too little attention, that habit, like a second nature, has the power of fixing in the mind new categorical forms derived from the appearances which impress us, and by them usually stripped of objective reality, but whose influence over our judgments is no less predetermining than that of the original categories. Hence we reason by the eternal and absolute laws of our mind, and at the same time by the secondary rules, ordinarily faulty, which are suggested to us by imperfect observation. This is the most fecund source of false prejudices, and the permanent and often invincible cause of a multitude of errors. The bias resulting from these prejudices is so strong that often, even when we are fighting against a principle which our mind thinks false, which is repugnant to our reason, and which our conscience disapproves, we defend it without knowing it, we reason in accordance with it, and we obey it while attacking it. Enclosed within a circle, our mind revolves about itself, until a new observation, creating within us new ideas, brings to view an external principle which delivers us from the phantom by which our imagination is possessed.
Thus, we know today that, by the laws of a universal magnetism whose cause is still unknown, two bodies (no obstacle intervening) tend to unite by an accelerated impelling force which we call gravitation. It is gravitation which causes unsupported bodies to fall to the ground, which gives them weight, and which fastens us to the earth on which we live. Ignorance of this cause was the sole obstacle which prevented the ancients from believing in the antipodes. “Can you not see,” said St. Augustine after Lactantius, “that, if there were men under our feet, their heads would point downward, and that they would fall into the sky?” The bishop of Hippo, who thought the earth flat because it appeared so to the eye, supposed in consequence that, if we should connect by straight lines the zenith with the nadir in different places, these lines would be parallel with each other; and in the direction of these lines he traced every movement from above to below. Thence he naturally concluded that the stars were rolling torches set in the vault of the sky; that, if left to themselves, they would fall to the earth in a shower of fire; that the earth was one vast plain, forming the lower portion of the world, etc. If he had been asked by what the world itself was sustained, he would have answered that he did not know, but that to God nothing is impossible. Such were the ideas of St. Augustine in regard to space and movement, ideas fixed within him by a prejudice derived from an appearance, and which had become with him a general and categorical rule of judgment. Of the reason why bodies fall his mind knew nothing; he could only say that a body falls because it falls.
With us the idea of a fall is more complex: to the general ideas of space and movement which it implies, we add that of attraction or direction towards a centre, which gives us the higher idea of cause. But if physics has fully corrected our judgment in this respect, we still make use of the prejudice of St. Augustine; and when we say that a thing has fallen, we do not mean simply and in general that there has been an effect of gravitation, but specially and in particular that it is towards the earth, and from above to below, that this movement has taken place. Our mind is enlightened in vain; the imagination prevails, and our language remains forever incorrigible. To descend from heaven
