Book of Demonstration

Classical Arabic Philosophy: An Anthology of Sources. Trans. Jon McGinnis and David C. Reisman. Indianapolis: Hackett Publishing Co. Inc., 2007.


“1. Perfect assent is certainty. Perfect conceptualization is to conceptualize something by means of a concise account of what it is in a manner proper to it, because conceptualizing something by means of what signifies it is to define the thing. We will begin (discussing) these two (activities) with a precise account of what is proper to perfect assent. By way of summary, assent is for someone to have a conviction about something to which a judgement can apply, by judging that what the thing is outside the mind accords with the object of conviction in one’s mind, where the truth is that the thing outside the mind does in fact accord with the object of conviction in the mind. Assent may apply both to what is true as well as to what is false. Assent may be certain, it may be approximately certain, it may be the assent that is called “the acquiescence of the soul” with respect to something (which is the one most removed from certainty), and (finally), there is nothing certain whatsoever in false assent. In fact, only the assent to something that is true can be certain.”

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