DEMONSTRATION AND SELF-EVIDENCE 19 



propositions. It takes a sufficient experience (spoken of by 

 St. Thomas as an experimentum which comes about from many 

 memories) ^° of the singular manifestations of a universally 

 necessary truth before we are ready to penetrate beyond the 

 accidentals of these singulars to the underlying necessity. This 

 experimeiituvi is not always easily achieved. And the intuitive 

 insight (into the necessity potentially in the expeiimentum) 

 effected by the possible intellect through the light of the agent 

 intellect is difficult as a matter of course. More often than not, 

 it seems, propositions which are self-evident in themselves are 

 not seen to be self-evident by us; and when they are, it is only 

 by way of a tremendously difficult dialectical procedure. ^^ 



To grasp the truth of a self-evident proposition one must first 

 grasp the meaning of the terms involved. Hence, the search for 



^"In II Post. Anal., lect. 20, n. 11; In IV Met., lect. 6, n. 599. 



^^ Thus far I have used the expression " dialectical " to refer to probable argu- 

 mentation. This type of dialectical discourse is supplementary to demonstration. 

 We can also speak of a pre-demonstrative dialectic — which prepares the way for 

 demonstration by manifesting the absolute premises of demonstration. This is the 

 way the term is used here. There is no question of a proof, in any strict sense of 

 the word, for a self-evident proposition. Assent to the self-evident proposition 

 depends upon and comes with an insight into the intrinsic intelligibility of the 

 proposition itself. The assent is automatic with the insight, but the insight may be 

 difficult to achieve. The way to insight may require long and complicated discourse 

 involving division, defuiition, and even argumentation. For example, one typical 

 dialectical device for manifesting the truth of a self-evident proposition is the 

 reduction of its contradiction to absurdity. (Cf. In III Met., lect. 5, n. 392.) The 

 important point is that once the threshhold of insight is achieved the assent is made 

 in virtue of the intrinsic intelligibOity of the proposition itself. The dialectic is a 

 scaffolding which can now be torn down, for it is not needed as a defense of the 

 self-evident proposition once seen (no matter how instrumental it might in fact 

 have been prior to msight) . Here precisely is where the immediate induction of the 

 principles of demonstration differs from the mediate induction of a conclusion from 

 a sufficient enumeration of singulars. The induced conclusion is assented to precisely 

 in vhtue of the enumeration of singulars and cannot be known without pointing to 

 them for evidence. This is not the case for the induced principle. No matter how 

 many singular wholes and parts have to be observed before a man sees into the 

 meaning of whole and part so that he knows the whole must be greater than its 

 parts, the proposition is seen to be true independently of each and all of these 

 singular wholes and parts. (In III Sent., d. 24, q. 1, a. 2, q. 1 ad 2: " Termini 

 principiorum natm'aliter notorum sunt comprehensibles nostro intellectui: ideo 

 cognitio quae consurgit de illis principiis, est visio. . . .") 



