is more easy to conclude one, than many things. To the subverter indeed, it is sufficient to dispute against one (part of the definition), (for having subverted any one part, we shall have subverted the definition,) but it is necessary for the confirmer, to prove that all those things are inherent, which are in the definition. Moreover, the confirmer must adduce an universal syllogism, since it is requisite that of every thing of which a name is predicated, the definition should be predicated, and besides this, vice versâ, if the assigned definition is to be proper. On the other hand, it is not requisite for the subverter to demonstrate the universal, since it suffices to show that the definition is not verified of any one of the things under the name, if also it should be necessary to subvert universally, neither thus, is reciprocation necessary in subversion, for it is enough that the subverter show universally, that the definition is not predicated of some one of those things, of which the name is predicated. On the contrary, it is not necessary to show that the name is predicated, of what the definition is not predicated. Further, if also it is present with every thing under the name, yet not with it alone, the definition will be subverted.
In like manner, it is with regard to property and genus, since in both, it is easier to subvert, than to confirm. About property then, it is evident from what we have stated, as for the most part property is assigned in conjunction, so that it is possible to subvert by taking away one (word); but he who confirms, must of necessity conclude every thing by syllogism. Now almost every thing else, which may be said of definition, will also be suitable to say of property, since the confirmer ought to show that it is inherent in every thing under the name, but it suffices for the subverter to show it non-inherent in one thing; if also it is inherent in every thing, but not in it alone, thus too, it becomes subverted, as was observed about definition. Concerning genus indeed, (it is evident,) because it is necessarily confirmed only in one way, if a person shows it present with every individual; nevertheless, it is subverted in two ways, for both if it has been shown not present with any, and not with a certain one, what was assumed in the beginning is subverted. Moreover, it is not enough, for the confirmer
