How to treat a plural count noun?

Solution 1:

The authors of the quoted text seem to have used the word class casually, or at least with less care than would be taken with it in, say, a philosophical text.

There are many millions of boys in the world, so one can, uncontroversially, say that the class of boys is large. But one definitely cannot express that by saying either 'Boy is large' or 'Boys are large'. This simple observation is enough to show that the word boy, in either the singular or the plural, does not denote (stand for, refer to) the class of boys.

What the word boy denotes is one instance of that class; boys denotes two or more (possibly all) instances of the class. Sometimes the context makes it clear that the instance(s) denoted are specific; sometimes the word denotes an abstract representative of the class. Speaking about an abstract representative of a class is, in a way, speaking 'about' the class, as it brings out the qualities that define the class. Speaking about a class, in that broad sense of about is, however, not the same as denoting the class itself.