The prime task of logics is to supply precise, purely formal standards of validity to distinguish valid from invalid arguments. While the domain of discourse which may be selected in logics is always restricted in some sense, one may pick out any kind of thing (perceptible, fictional or potential) one likes or believes in, and one may construct whatever fancy predicate or predicate expression one feels desire for. So far as formal logics is concerned logicians normally cannot and do not bar any entity or type of entity people wish to include in their domain. This does not mean, of course, that individual logicians may not be interested in ontological questions. (Such a logician may personally dismiss names as strictly redundant, for instance, but at the same time have no scruples about artificial solutions like rendering every   a=   'simply' as a predicate expression   A   which would be true solely of the object named "a".)

The fictitious objects or things logics allows us to talk about are not necessarily beings created out of the imagination with some fancy combination of brilliant and/or gaudy attributes as we so often find in religious ideologies, in fairy tales, or in other supernatural thought. Such fictitious things may also be conceptual constructions, like sets or collections, soberly and coherently represented in a formal, philosophical or mathematical system. In logics a domain of discourse may encompass all these fictional entities besides (really) existing ones. What is even more interesting from the systematic point of view is that such a domain may include both discrete individuals and the parts of those individuals, from which they are not distinct (so long as all these individuals are definite, distinguishable objects or things). And it is logically also quite as acceptable --without making existential presuppositions-- to take in attributes as elements in a logical domain besides the things themselves and besides the parts of those things. Having done this it is only a question of translation to adequately write down in the logical calculus that a thing has parts and that it has attributes, using the same two-place relation of having.