PART ONE

THE CRITERION OF CERTAINTY

CHAPTER 7

There is a single principle of certainty for
all possible propositions

1061. I have not yet moved to show against the sceptics that a valid principle of certainty exists for human beings. This present chapter aims only at demonstrating what such a principle, if it really exists, would have to be in order to merit its name.
If the principle of certainty exists, it can only be one for all possible propositions. This is a consequence of what has been said.
I showed that, if we wished to know the truth of a proposition, we needed to discover its ultimate reason.(18) Thus we had to know whether this ultimate reason must also be the final reason of all other propositions. I found that the nature of this ultimate reason was not only the principle of certainty but also the principle of human knowledge (cf. 1059–1060).

Throughout the whole of volume one, however, we have seen that there is only one principle of all human acts of knowledge, BEING IN ALL ITS UNIVERSALITY.(19) If, therefore, the principle of certainty exists, it can only be one for all possible propositions, and must in fact be this unique idea of being, inserted in us by nature to make us intelligent, that is, to make us capable of perceiving the truth.(20)

(18) St. Augustine recognises that ‘ideas’ can fittingly be called ‘reasons’. In fact a reason can only be an idea. The great bishop of Hippo says: Ideas latine possumus vel formas vel species dicere, ut verbum e verbo transferri videamur. Si autem RATIONES eas vocemus, ab interpretandi quidem proprietate discedimus: rationes enim graece [Greek] appellantur, non ideae, sed tamen quisquis hoc vocabulo uti voluerit, a re ipsa non errabit [In our own language we can call ideas forms or species, using one word in place of another. But calling them REASONS is not strictly correct. In Greek ‘reasons’ are called [Greek], not ‘ideas’. However, if anyone prefers to use ‘reasons’, he would not be making a mistake] (Lib. 83 Quaest., 2. 46).

(19) Ancient thinkers recognised that the principle of certainty had to be something most universal, as we can see in Sextus (Hypotyposis, bk. 2, c. 9).

(20) In this sense the statement by the author of Saggio sull’Indifferenza must be true: ‘Certainty is the essential basis of reason’ (5, 2).