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. [19] "We think we understand a thing perfectly, whenever we think we know the cause by which the thing is, that it is really the cause of that thing, and that the thing cannot possibly be otherwise." [Tr.'s add.] [20] Lib. iv. c. 1. [21] "Now it is common to all principles, that they are the first thing through which [anything] is, or arises, or is understood." [Tr.'s add.] [22] "There are four causes: first, the essence of a thing itself; second, the _sine qua non_ of a thing; third, what first put a thing in motion; fourth, to what purpose or end a thing is tending." [Tr.'s add.] [23] "Suarii disputationes metaph." Disp. 12, sect. 2 et 3. [24] Hobbes, "De corpore," P. ii. c. 10, § 7.