Using the word "by" before "whom"

Question

I read the following sentence in a newspaper about a restaurateur's reasons for abolishing tipping: "Many of the owners other reasons sound like the typical complaints of British tourists, who are perpetually confused by whom to pay and how much."

"By" preceding the use of "whom" does not sound right to me. For me the word "by" introduces the performer of an action, whereas I always thought "whom" refers to an object. This must be good English as it was in reputable newspaper, so can anyone explain how this makes sense?

Answer 1

By is a versatile preposition. The OED records 39 separate senses of the word, and when we get to sense 26, we find it means "about" or "concerning." So the thing that confuses the Brits is the matter of tipping, in particular

whom to pay

(not to mention how much to pay). Whom is properly in the objective case because it is the object of the infinitive "to pay."

Answer 2

"Whom" is an objective case form, but it doesn't refer to an object. Case forms are grammatical, not semantic. And in a passive construction, like this one, "by" is followed by a logical subject, and a subject is not necessarily the performer of an action (though it may be).

None of that really matters, here, because the object of the preposition "by" is not "whom", but rather "whom to pay". That is, the subject of the active sentence corresponding to this passive would be "whom to pay" -- the active form is "Whom to pay confuses British tourists." In this active form, "whom" has the objective case form because it is the direct object of "pay".

Many English speakers no longer use an objective case form "whom", but instead use "who", regardless of case. For them, in the above examples "who" would be used rather than "whom".

Answer 3

'By' does indicate the agent, but the clause is in passive voice (verb = 'are confused') so it's subject is not the agent. 'Whom' is the accusative case of 'who', used whenever the case is not nominative (=subject). The important point is that subject and agent are only the same thing in active voice. In passive voice the subject is the patient (prop) rather than the agent (doer) of the action.