Plattner, in his Aphorisms, § 868, says: "What is called reason and conclusion within our knowledge (principium cognoscendi, ratio—rationatum), is in reality cause and effect (causa efficiens—effectus). Every cause is a reason, every effect a conclusion." He is therefore of opinion that cause and effect, in reality, correspond to the conceptions reason and consequence in our thought; that the former stand in a similar relation with respect to the latter as substance and accident, for instance, to subject and predicate, or the quality of the object to our sensation of that quality, &c. &c. I think it useless to refute this opinion, for it is easy to see that premisses and conclusion in judgments stand in an entirely different relation to one another from a knowledge of cause and effect; although in individual cases even knowledge of a cause, as such, may be the reason of a judgment which enunciates the effect.[43]
§ 12. Hume.
No one before this serious thinker had ever doubted what follows. First, and before all things in heaven and on earth, is the Principle of Sufficient Reason in the form of the Law of Causality. For it is a veritas æterna: i.e. it is in and by itself above Gods and Fate; whereas everything else, the understanding, for instance, which thinks that principle, and no less the whole world and whatever may be its cause—atoms, motion, a Creator, et cætera—is what it is only in accordance with, and by virtue of, that principle. Hume was the first to whom it occurred to inquire whence this law of causality derives its authority, and to demand its credentials. Everyone knows the result at which he arrives: that causality is nothing beyond the empirically perceived succession of things and states in Time, with which habit has made us familiar. The fallacy of this result is felt at once, nor is it difficult to refute. The merit lies in the question itself; for it became the impulse and starting-point for Kant's profound researches, and by their means led to an incomparably deeper and more thorough view of Idealism than the one which had hitherto existed, and which was chiefly Berkeley's. It led to transcendental Idealism, from which arises the conviction, that the world is as dependent upon us, as a whole, as we are dependent upon it in detail. For, by pointing out the existence of those transcendental principles, as such, which enable us to determine à priori, i.e. before all experience, certain points concerning objects and their possibility, he proved that these things could not exist, as they present themselves to us, independently of our knowledge. The resemblance between a world such as this and a dream, is obvious.
§ 13. Kant and his School.
Kant's chief passage on the Principle of Sufficient Reason is in a little work entitled "On a discovery, which is to permit us to dispense with all Criticism of Pure Reason."[44] Section I., lit. A. Here he strongly urges the distinction between "the logical (formal) principle of cognition 'every proposition must have its reason,' and the transcendental (material) principle 'every thing must have its cause,'" in his controversy with Eberhard, who had identified them as one and the same.—I intend myself to criticize Kant's proof of the à priori and consequently transcendental character of the law of causality further on in a separate paragraph, after having given the only true proof.
With these precedents to guide them, the several writers on Logic belonging to Kant's school; Hofbauer, Maass, Jakob, Kiesewetter and others, have defined pretty accurately the distinction between reason and cause. Kiesewetter, more especially, gives it thus quite satisfactorily:[45] "Reason of knowledge is not to be confounded with reason of fact (cause). The Principle of Sufficient Reason belongs to Logic, that of Causality to Metaphysics.[46] The former is the fundamental principle of thought; the latter that of experience. Cause refers to real things, logical reason has only to do with representations."
Kant's adversaries urge this distinction still more strongly. G. E. Schultze[47] complains that the Principle of Sufficient Reason is confounded with that of Causality. Salomon Maimon[48] regrets that so much should be said about the sufficient reason without an explanation of what is meant by it, while he blames Kant[49] for deriving the principle of causality from the logical form of hypothetical judgments.
F. H. Jacobi[50] says, that by the confounding of the two conceptions, reason and cause, an illusion is produced, which has given rise to various false speculations; and he points out the distinction between them after his own fashion. Here, however, as is usual with him, we find a good deal more of self-complacent phrase-jugglery than of serious philosophy.
How Herr von Schelling finally distinguishes reason from cause, may be seen in his "Aphorisms introductory to the Philosophy of Nature,"[51] § 184, which open the first book of the first volume of Marcus and Schelling's "Annals of Medecine." Here we are taught that gravity is the reason and light the cause of all things. This I merely quote as a curiosity; for such random talk would not otherwise deserve a place among the opinions of serious and honest inquirers.