Errors with respect to grammatical number—disagreement between subject and verb or between pronoun and antecedent—are often subtle but nonetheless generally recognized as errors by all but the most militant descriptivists. There is one glaring exception to this observation, however, which is gaining wide acceptance even in some educated circles: the use of a plural third person pronoun with an indefinite singular antecedent such as anyone, everybody, no one, a person, or each party. This usage is defended by a variety of arguments, all of roughly equal merit:

(1) The antecedents in question are in some sense plural.

Gilman, for example, argues that "the indefinite pronouns are usually plural in implication" and characterizes the reference to an indefinite by a plural pronoun, as in too hideous for anyone in their senses to buy, as a case of "notional agreement", i.e., agreement based on meaning rather than form. The principle is well established, but more properly illustrated by another of Gilman's examples: A bunch of the boys were whooping it up in the Malamute saloon. Here the formally singular bunch is considered as comprising several distinct members, and thus agrees notionally with the plural verb were whooping. The essential difference between these two constructions, which seems to escape Gilman and others, is that while bunch denotes a set of people taken together, anyone denotes a single person of unspecified identity. The failure to appreciate this distinction—between a set, on the one hand, and a variable ranging over its elements, on the other—accounts for much of the confusion surrounding this issue.

Linguistic psychologist Steven Pinker, in attempting to defend the solecism Everyone returned to their seats, actually throws some light on the problem by casting the sentence as a proposition of formal logic:

... everyone and they are not an "antecedent" and a "pronoun" referring to the same person in the world, which would force them to agree in number. They are a "quantifier" and a "bound variable," a different logical relationship. Everyone returned to their seats means "For all X, X returned to X's seat." The "X" does not refer to any particular person or group of people; it is simply a placeholder that keeps track of the roles that players play across different relationships. In this case, the X that comes back to a seat is the same X that owns the seat that X comes back to. The their there does not, in fact, have plural number, because it refers neither to one thing nor to many things; it does not refer at all.

Pinker's contention that their is not plural in this context is an interesting variation on the argument. We may be shocked by this claim, but as we observe elsewhere (see PLURAL NOUNS), there are those who have difficulty identifying a noun as plural unless it happens to end with `s'; perhaps the same is true of common pronouns. This hypothesis is supported by observed resistance to similar abuse of the reflexive form themselves, which has given rise to the formation of a bold alternative:

The question at hand is why would a person want to purposefully cause harm to themself and at the same time cause harm to others?
-- Daily Illini, 9/20/2000.

(2) Their, they, and them are the best approximations to singular epicene pronouns that are available in English.

Here is an argument based not on logic, grammar, or idiom, but rather on the inability of its proponents to express their thoughts in standard English, and the presumption that such failure on their part constitutes grounds for the corruption of established syntax. Moreover, the premise is false: English comes equipped with a serviceable set of generic singular pronouns—his, he, him, etc.—which, though masculine in gender (see GENDER), have performed adequately in this role for several centuries. Fowler, in supporting this convention, dismisses two alternatives as unacceptable: (1) constructions such as himself or herself, which he characterizes as "so clumsy as to be ridiculous except when explicitness is urgent," and (2) the substitution of plural pronouns for singular, a practice that "sets the literary man's teeth on edge." Yet another option is recommended here to those who are unhappy with established usage: consider relocating to a place where a more suitable language is spoken. This may require some search, as gender plays a more central role in most Indo-European languages than in English. The Romance languages, for example, are plagued with both singular and plural masculine epicene pronouns, and assign genders indiscriminately to nouns and adjectives as well. Mandarin Chinese, on the other hand, is reported to include a full complement of neuter personal pronouns and may be an agreeable candidate.

(3) Various respectable people have engaged in this usage; hence, it must be correct.

This seems to be the only criterion for acceptability that is recognized by New Age linguistic anarchists like Henry Churchyard, the host of an "anti-pedantry" Web site that includes a page devoted to the enumeration of instances of "singular 'their', etc.", as he terms this construction, in the writings of Jane Austen. As evidence of its correctness, he claims (showing the same facility with numbers as with words) to have found eighty-seven such occurrences: eighty-two in Austen's literary works, and the remaining four in her letters and other non-literary writings. The following example is taken from Sense and Sensibility:

..it was all conjectural assertion on both sides; and every body had a right to be equally positive in their opinion, and to repeat it over and over again as often as they liked."

..for they say every body is in love once in their lives, and I shall have been let off easily.

I cannot deny a certain admiration for his scholarship, but when Churchyard first brought his efforts to my attention (hate mail, from a descriptivist yet!), I was reminded of Fowler's reaction to a similar argument posed by Otto Jespersen:

I confess to attaching more importance to my instinctive repugnance for [such nonsense] than to Professor Jespersen's demonstration that it has been said by more respectable authors than I had supposed. *