Fifth: In their view the quiddity of a thing can be conceived only through a real definition—one fashioned from the essential elements that are shared and those that differentiate, the combination of genus and differentia. Yet they themselves concede that such a definition is either unattainable or exceedingly difficult to produce. If that were so, no quiddity would ever, or at least would seldom, be conceived. But quiddities in fact are conceived; hence it is clear that conceptions do not depend on definitions.
Sixth: Real definitions, according to them, apply only to composite realities, namely those species that possess both genus and differentia. As for what is simple and thus does not join anything else under a genus—as some of them illustrate with the Intellects—it has no definition at all. Nevertheless they do in fact know it, and it figures among the very conceptions they deem necessary. This again shows that conceptions dispense with definitions. Indeed, if such simple entities can be known without a definition, then the composite species should be still easier to know, for they are closer to sensory experience and their individual instances are observable.
They also admit that assent does not hinge upon the complete conception obtained by a real definition; the slightest conception, even if only through an ad hoc description, suffices—and their conception of the Intellects is of this sort. By this they acknowledge that conception as such is not contingent on a real definition. They merely contend that what is contingent upon it is the full grasp of the reality. God willing, we shall show that for every conception there is a more complete one above it: we never conceive anything together with all its concomitants so perfectly that nothing escapes us. The more attributes of a thing one apprehends, the more perfect one’s conception becomes.
As for deeming some attributes part of a thing’s essence while others are external to it, this corresponds to no objective reality. What they call “internal” is simply what the word signifies by implication, whereas the “external but necessary” attributes are those it signifies by entailment. Thus the attributes said to be inside the quiddity are merely those included in the speaker’s intended meaning, and the necessary external attributes are those that follow from that intended meaning. All of this hinges on the speaker’s intent and does not relate to any fixed reality of the described object itself. We have set out their terminology elsewhere and demonstrated at length that what they call “quiddity” is nothing more than something posited in the mind, not something realized in external existence; and what is posited in the mind varies according to what each individual posits there. It is therefore impossible that