Plural genitive endings in -i

Question

This is a speculative question that (I hope) has a good answer from historical linguistics.

My starting observation was that all nouns appear to have a plural genitive ending in -um: -arum, -orum, -(i)um, -uum, erum. Just as I began thinking of this as a kind of ironclad rule, it occurred to me that certain plural personal pronouns end in -i, e.g.:

• sui
• nostri
• vestri

It's interesting, though, that two of these examples are only used in a specific case: the -um ending (vestrum/nostrum) is still used for the partitive genitive.

By all accounts, these words look like they are singular: in fact, the reflexive pronoun is the exact same in the singular and plural. Am I right to see this -i ending in the genitive plural as a bit of an anomaly? If so, do we have a reasonable explanation for why it is there?

Answer 1

This answer is based on the intuition I have long held: genitives like nostrum and vestri are not forms of the personal pronouns nos and vos, but of the substantivized possessive adjectives. I have no sources to back this up, but I am posting these thoughts here for scrutiny.

Some pronouns (ego, tu, nos, vos, se) have an associated possessive pronoun (meus, tuus, noster, vester, suus) that takes some of the functions of the genitive. Therefore the role of the genitive is not directly comparable to nouns and most pronouns. These special pronouns do not have a genitive form in the completely usual sense.

My intuition has always been that sui, nostri, vestri and the like are singular genitives of the substantivized neuter adjective suum/nostrum/vestrum. Thus, sui/nostri/vestri/mei/tui are not forms of the personal pronouns themselves, but rather of the related possessive pronoun. The putative noun nostrum is almost synonymous with res nostra, so you could read nostri as rei nostrae. Notice that it is irrelevant that nos is plural; the possessive adjective noster is only used in the singular here. Therefore the -i you see is a singular genitive ending, and the connection to plural comes from the meaning of the word noster.

This reasoning does not extend to all uses of the genitive as such, but the same principle applies. For partitive genitive, you always have nostrum/vestrum — at least I have never seen nostri/vestri partitively. For example, "one of us" would be unus nostrum, which I read roughly as unus virorum nostrorum. Again, noster is substantivized, and here means "a man from our group". The shorter genitive plural ending -um instead of -orum is possible for many words, and nostrum and vestrum sound just like the kind of thing that I expect to wind up having the shorter variant.

Of course, these genitives of the possessive pronouns can start a life of their own and obtain new uses by analogy. See this question, for example. Most instances of nostrum/vestrum used a possessive genitive actually make sense when parsed as plural genitives of a substantivized possessive pronoun.

Answer 2

It's all too easy to confound the reflexive pronoun (which only exists in the oblique cases) with the possessive adjective suus, sua, suum (declined like bonus). The genitive plural suorum , etc, of the latter is found widely in classical literature, which I personally find more readily acceptable than the singular usage of the reflexive pronoun.

I'm not altogether sure about describing this -i ending as if for a genitive plural of pronouns. Although the usage certainly seems to exist, I wouldn't resort to it myself — but I think that you're right to suggest an anomaly, or at least an aberration. Maybe someone familiar with these backwaters of grammar will give chapter and verse from a modern analysis, such as Harm Pinkster's 'Oxford Latin Syntax' (OUP 2015).

(As an aside, I believe that the passage you quote, quod illi semper sui causa fecerant, cum eos nemo rogaret, . . . . is much disputed, with many commentators preferring the reading sua causa.)