In expressions like either you or I is in the wrong, we must
consider either not only as a pronoun, but as the leading pronoun of the proposition; a pronoun of which or I is an explanation; and, finally, as the pronoun which determines the person of the verb. Either you or I is wrong=one of us (you or I) is wrong.
Then, as to expressions like I, or you, am in the wrong. Here, I is the leading pronoun, which determines the person of the verbs; the words, or you, being parenthetic, and subordinate. These statements bear upon the rules of p. 457.
[§ 622]. Will this principle justify such expressions as either they or we is in the wrong?
Or will it justify such expressions as either he or they is in the wrong?
Or will it justify such expressions as I or they am in the wrong? In all which sentences one pronoun is plural.
Perhaps not. The assumption that has been just alluded to, as helping to explain certain doubtful constructions, is the following, viz., that in cases of apposition, disjunction, and complex terms, the first word is the one which determines the character of the sentence wherein it occurs. This is a practice of the English language, which, in the opinion of the present writer, nothing but a very decided preponderance of a difference in person, gender, or number, can overrule. Such may fairly be considered to be the case in the three examples just adduced; especially as there is also the secondary influence of the conjunctional character of the word either. Thus, although we say,—
One of two parties, they or we, is in the wrong.
We also say,—
Either they or we are in the wrong.