On the Fourfold Root of the Principle of Sufficient...

A more or less accurately defined, abstract expression for so fundamental a principle of all knowledge must have been found at a very early age; it would, therefore, be difficult, and besides of no great interest, to determine where it first appeared. Neither Plato nor Aristotle have formally stated it as a leading fundamental principle, although both often speak of it as a self-evident truth. Thus, with a naïveté which savours of the state of innocence as opposed to that of the knowledge of good and of evil, when compared with the critical researches of our own times, Plato says: ἀναγκαῖον, πάντα τὰ γιγνόμενα διά τινα αἰτίαν γίγνεσθαι· πῶς γὰρ ἂν χωρὶς τούτων γίγνοιτο;[16] (necesse est, quæcunque fiunt, per aliquam causam fieri: quomodo enim absque ea fierent?) and then again: πᾶν δὲ τὸ γιγνόμενον ὑπ' αἰτίου τινὸς ἐξ ἀνάγκης γίγνεσθαι· παντὶ γὰρ ἀδύνατον χωρὶς αἰτίου γένεσιν σχεῖν[17] (quidquid gignitur, ex aliqua causa necessario gignitur: sine causa enim oriri quidquam, impossibile est). At the end of his book "De fato," Plutarch cites the following among the chief propositions of the Stoics: μάλιστα μὲν καὶ πρῶτον εἶναι δόξειε, τὸ μηδὲν ἀναιτίως γίγνεσθαι, ἀλλὰ κατὰ προηγουμένας αἰτίας[18] (maxime id primum esse videbitur, nihil fieri sine causa, sed omnia causis antegressis).

In the "Analyt. post." i. 2, Aristotle states the principle of sufficient reason to a certain degree when he says: ἐπίστασθαι δὲ οἰόμεθα ἕκαστον ἁπλῶς, ὅταν τὴν τ' αἰτίαν οἰόμεθα γινώσκειν, δι' ἣν τὸ πρᾶγμα ἔστιν, ὅτι ἐκείνου αἰτία ἐστίν, καὶ μὴ ἐνδέχεσθαι τοῦτο ἄλλως εἶναι. (Scire autem putamus unamquamque rem simpliciter, quum putamus causam cognoscere, propter quum res est, ejusque rei causam esse, nec posse eam aliter se habere.)[19] In his "Metaphysics," moreover, he already divides causes, or rather principles, ἀρχαί, into different kinds,[20] of which he admits eight; but this division is neither profound nor precise enough. He is, nevertheless, quite right in saying, πασῶν μὲν οὖν κοινὸν τῶν ἀρχῶν, τὸ πρῶτον εἶναι, ὅθεν ἢ ἔστιν, ἢ γίνεται, ἢ γιγνώσκεται.[21] (Omnibus igitur principiis commune est, esse primum, unde aut est, aut fit, aut cognoscitur.) In the following chapter he distinguishes several kinds of causes, although somewhat superficially and confusedly.

In the "Analyt. post." ii. 11, he states four kinds of causes in a more satisfactory manner: αἰτίαι δὲ τέσσαρες· μία μὲν τό τι ἦν εἶναι· μία δὲ τὸ τινῶν ὄντων, ἀνάγκη τοῦτο εἶναι· ἑτέρα δὲ, ἥ τι πρῶτον ἐκίνησε· τετάρτη δὲ, τὸ τίνος ἕνεκα.[22] (Causæ autem quatuor sunt: una quæ explicat quid res sit; altera, quam, si quædam sint, necesse est esse; tertia, quæ quid primum movit; quarta id, cujus gratia.) Now this is the origin of the division of the causæ universally adopted by the Scholastic Philosophers, into causæ materiales, formales, efficientes et finales, as may be seen in "Suarii disputationes metaphysicæ"[23]—a real compendium of Scholasticism. Even Hobbes still quotes and explains this division.[24] It is also to be found in another passage of Aristotle, this time somewhat more clearly and fully developed ("Metaph." i. 3.) and it is again briefly noticed in the book "De somno et vigilia," c. 2. As for the vitally important distinction between reason and cause, however, Aristotle no doubt betrays something like a conception of it in the "Analyt. post." i. 13, where he shows at considerable length that knowing and proving that a thing exists is a very different thing from knowing and proving why it exists: what he represents as the latter, being knowledge of the cause; as the former, knowledge of the reason. If, however, he had quite clearly recognized the difference between them, he would never have lost sight of it, but would have adhered to it throughout his writings.

Now this is not the case; for even when he endeavours to distinguish the various kinds of causes from one another, as in the passages I have mentioned above, the essential difference mooted in the chapter just alluded to, never seems to occur to him again. Besides he uses the term αἴτιον indiscriminately for every kind of cause, often indeed calling reasons of knowledge, and sometimes even the premisses of a conclusion, αἰτίας, as, for instance, in his "Metaph." iv. 18; "Rhet." ii. 2; "De plantis." p. 816 (ed. Berol.), but more especially "Analyt. post." i. 2, where he calls the premisses to a conclusion simply αἰτίαι τοῦ συμπεράσματος (causes of the conclusion). Now, using the same word to express two closely connected conceptions, is a sure sign that their difference has not been recognised, or at any rate not been firmly grasped; for a mere accidental homonymous designation of two widely differing things is quite another matter. Nowhere, however, does this error appear more conspicuously than in his definition of the sophism non causæ ut causa, παρὰ τὸ μὴ αἴτιον ὡς αἴτιον, (reasoning from what is not cause as if it were cause), in the book "De sophisticis elenchis," c. 5. By αἴτιον he here understands absolutely nothing but the argument, the premisses, consequently a reason of knowledge; for this sophism consists in correctly proving the impossibility of something, while the proof has no bearing whatever upon the proposition in dispute, which it is nevertheless supposed to refute. Here, therefore, there is no question at all of physical causes.

Still the use of the word αἴτιον has had so much weight with modern logicians, that they hold to it exclusively in their accounts of the fallacia extra dictionem, and explain the fallacia non causæ ut causa as designating a physical cause, which is not the case. Reimarus, for instance, does so, and G. E. Schultze and Fries—all indeed of whom I have any knowledge. The first work in which I find a correct definition of this sophism, is Twesten's Logic. Moreover, in all other scientific works and controversies the charge of a fallacia non causæ ut causa usually denotes the interpolation of a wrong cause.

Sextus Empiricus presents another forcible instance of the way in which the Ancients were wont universally to confound the logical law of the reason of knowledge with the transcendental law of cause and effect in Nature, persistently mistaking one for the other. In the 9th Book "Adversus Mathematicos," that is, the Book "Adversus Physicos," § 204, he undertakes to prove the law of causality, and says: "He who asserts that there is no cause (αἰτία), either has no cause (αἰτία) for his assertion, or has one. In the former case there is not more truth in his assertion than in its contradiction; in the latter, his assertion itself proves the existence of a cause."

By this we see that the Ancients had not yet arrived at a clear distinction between requiring a reason as the ground of a conclusion, and asking for a cause for the occurrence of a real event. As for the Scholastic Philosophers of later times, the law of causality was in their eyes an axiom above investigation: "non inquirimus an causa sit, quia nihil est per se notius," says Suarez.[25] At the same time they held fast to the above quoted Aristotelian classification; but, as far as I know at least, they equally failed to arrive at a clear idea of the necessary distinction of which we are here speaking.