Not minding my own business the other day, I overheard someone say to a friend, He’s one of those annoying persons who pays a bill the day he receives it. Something is amiss here, and a brief explanation might be in order—if only to help keep our thinking straight.
We remember there are three kinds of sentences in English: simple, compound, and complex. Simple and compound sentences have only independent clauses; complex sentences include at least one subordinate clause. In a sentence like He’s one of those annoying persons who pays a bill the day he receives it, the section that begins with the relative pronoun who constitutes the subordinate element, because relative pronouns (who, which, that) produce clauses that function most often as adjectives, and adjectives do not work alone but are attached to nouns. And that last detail, in fact, is material to our analysis here.
If we bracket the relative clause, then, the entire string of words from the relative pronoun to the period (who pays a bill the day he receives it) works as one adjective which qualifies the meaning of the noun persons. Pronouns always (except when we’re asking a question) point to an antecedent, a word usually earlier in the same sentence they work with, and here the speaker was referring to certain persons, those who are apparently both able and willing to have no financial obligation hanging like a Damoclean sword over their heads. The nine-word adjective who pays a bill the day he receives it defines those persons the speaker also found annoying (said jocularly), and those two adjectives, one in the form of a clause and the other in the form of a single word, limit or qualify or focus our attention on just those people the speaker had in mind.
All of that analysis is necessary to see clearly, then, that the verb of the relative clause, pays, is referring grammatically through the relative pronoun who to the antecedent persons. Whether the verb of a relative clause is singular or plural depends upon the number of its antecedent, so because persons is a plural noun, its verb should therefore be plural. The verb pays, however, is singular, and there is where the speaker tripped up: persons who pay, not persons who pays. But no sooner do we agree to that correction than another presents itself. Within the relative clause is another clause, he receives it, and we now have to be clear about the antecedent of this pronoun he. Looking closely we’ll see that its grammatical antecedent is also the plural noun persons, and so he should be they and receives should receive: one of those persons who pay a bill the day they receive it.
What will flip this linguistic optical illusion for you is to remember that there is a difference between grammatical reference and logical reference. We know that the speaker was referring logically to a particular individual he knew, the person named indirectly by the pronoun he, the subject of the first clause. But that independent clause was meant merely to identify that individual with a certain category of person, those who pay a bill the day they receive it. This complex sentence is making, in fact, only one main assertion, that he, a certain known individual, is a member of a certain logical class of persons, those who pay their bills the day they receive them; it is not, strange to say, explicitly asserting that this individual in question himself pays a bill the day he receives it—if it were, it would say just that and not refer to persons. The speaker’s original statement, though, lost sight of this one logical assertion, and he marshalled his grammar to suggest another, namely, that this individual does the same thing those persons do, pays a bill the day he receives it. That grammar mixed up the logic, and that is why getting the grammar straight is so important.