A challenging issue in the source is whether a singular noun marked for exhaustive inclusion can apply to all individuals of a kind. The grammatical singular form must be distinguished from the range of individuals to whom a proposition distributes.
For example, in «لَا رَجُلَ فِي الدَّارِ», the negation excludes any man in the house, whereas the bare singular morphology of «الرَّجُلُ» does not by itself settle whether only one particular man is intended.
A classical objection is that a singular term signifies unity, so how can it include many? The reply distinguishes the unity of the nominal form from the distribution of a rule over individuals.