Philosophers sometimes distinguish classes from
types and
kinds. We can talk about the class of human beings, just as we can talk about the type (or natural kind), human being, or humanity. How, then, might classes differ from types? One might well think they are not actually different
categories of being, but typically, while both are treated as
abstract objects, classes are not usually treated as
universals, whereas types usually are. Whether natural kinds ought to be considered universals is vexed; see
natural kind.
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