159. Here I shall notice the errors of those methods which isolate man's faculties, and, in order better to know the mind, disfigure and mutilate it. One of the most constant and fundamental facts of ideological and psychological science, is the multiplicity of acts and faculties of the soul, notwithstanding its simplicity attested by the unity of consciousness. There is in man, and in the universe, an assemblage of laws, the effects of which are simultaneously evolved with harmonious regularity; to separate them, is often equivalent to placing them in contradiction; for, no one of them being capable of producing its effect if isolated, but requiring to be combined with the others, they produce, when made to operate alone, instead of their regular effects, the most hideous monstrosities. If you retain in the world only the law of gravitation not combined with that of projection, every thing will be precipitated towards one centre; instead of that infinity of systems which adorn the firmament, you will have only a rude and indigested mass. If you destroy gravitation, and preserve the force of projection, all bodies will be decomposed into imperceptible atoms, and be dispersed, like most subtle ether, through regions of immensity.[(15)]
[CHAPTER XVI.]
CONFUSION OF IDEAS IN DISPUTES ON THE FUNDAMENTAL PRINCIPLE.
160. There are, in our opinion, various principles, which, with regard to the human intellect, may be called equally fundamental, both because they serve as foundation in the common and scientific orders, and because they do not rest upon any other, since it is impossible to assign any one which enjoys this quality as an exclusive privilege. In seeking the fundamental principle, it is customary in the schools to observe that they do not endeavor to find a truth from which all others emanate, but an axiom the destruction of which draws with it that of all other truths, and the firmness of which sustains them, at least indirectly, in such manner that whoever denies them may be refuted by indirect demonstration, or reduction ad absurdum; that is, admitting the above axiom, it may follow that whoever denies the others will be convicted of being in opposition to one which he himself has acknowledged to be true.
161. It has been much disputed whether this or that principle merit the preference. We believe that there is here a confusion of ideas, proceeding in great part from not sufficiently marking the limits of testimonies so distinct as those of consciousness, of evidence, and of common sense.
Descartes' famous principle, I think, therefore I am; that of contradiction, it is impossible for a thing to be and not to be at the same time; and what is called the principle of the Cartesians, whatever is contained in the clear and distinct idea of anything, may be affirmed of it with all certainty; are the three principles that have divided the schools. In favor of each, reasons the most powerful, and even conclusive against the others, considering the ground on which the question was placed, have been brought forward.
If you are not certain that you think, argues the partisan of Descartes, you cannot be certain even of the principle of contradiction, or know the criterion of evidence to be valid; for both, it is necessary to think; whoever affirms or denies anything, thinks; without thought, neither affirmation nor negation is possible. But let us admit thought: we have already a foundation, and one of such a nature that we find it in ourselves, attested by consciousness, irresistibly forcing upon us the certainty of its existence. The foundation once laid, we see how the edifice can be raised; for this we need not go out of our own thought; there is the luminous point to conduct us in the path to truth; let us follow its splendor, and having established an immovable point, let us draw from it the mysterious thread to guide us in the labyrinth of science. Thus our principle is the first, the basis of all others; it has sufficient power to sustain itself, sufficient also to impart firmness to others.
This language is certainly reasonable; but it has this fault, that the conviction which it is intended to produce, is neutralized by the not less reasonable language of those who hold a directly contrary opinion. One who maintains the principle of contradiction may reason thus: if you do not admit it to be impossible for the same thing to be and not be at the same time, it may be possible that you think and do not think at the same time; your assertion, then, I think, is of no weight, for its opposite, I do not think, may, at the same time, be true. In this case, the conclusion of existence is invalid; for, even admitting the legitimacy of the consequence, I think, therefore I am, as we know on the other hand that this other premise, I do not think, is possible, the deduction cannot be made. Nor is the other principle: whatever is contained in the clear and distinct idea of anything, may he affirmed of it with all certainty, of any more value without the principle of contradiction; because if being and not-being are possible at the same time, an idea may be clear and obscure, distinct and confused; a predicate may be contained and not contained in the subject; we may be certain and uncertain, affirm and deny; therefore it is of no service.