is also clear when there will and will not be an Elenchus. For all things being granted, or the answers being arranged alternately, for instance, the one being negative and the other affirmative, an elenchus may be produced, since there was a syllogism when the terms were as well in this as in that way, so that if what is laid down should be contrary to the conclusion, it is necessary that an elenchus should be produced, for an elenchus is a syllogism of contradiction. If however nothing is granted, it is impossible that there should be an elenchus, for there was not a syllogism when all the terms are negative, so that there will neither be an elenchus, for if there is an elenchus, it is necessary there should be a syllogism, but if there is a syllogism, it is not necessary there should be an elenchus. Likewise, if nothing should be universally laid down in the answer, for the determination of the elenchus and of the syllogism will be the same.
Chapter 21
Sometimes it happens, that as we are deceived in the position of the terms, so also deception arises as to opinion, for example, if the same thing happens to be present with many things primary, and a person should be ignorant of one, and think that it is present with nothing, but should know the other. For let A be present with B and with C, per se, (that is, essentially,) and let these, in like manner, be with every D; if then somebody thinks that A is with every B, and this with every D, but A with no C, and this with every D; he will have knowledge and ignorance of the same thing, as to the same.
