Is this sentence correct? Many countries now require that one have substantial savings in the bank before retiring there. The word one is a singular pronoun, so shouldn’t the verb be has, not have? It should not and here’s why.
The sentence illustrates what is called the subjunctive mood, and before that imposing terminology tempts us to conclude that it’s just not practical to consider, let’s note that if one wrote that one has substantial savings in this sentence, one would not be writing standard English. That standard may change, but it hasn’t yet. The subjunctive is one of three moods that an English verb may assume. The term mood, or mode, refers to the manner in which the writer regards a statement: if as a fact, the verb must be in the indicative mood; if as a direct command, the imperative mood; and if as a condition or hypothesis or possibility, the subjunctive mood.
The system of verb moods is set up to recognize that we humans have a peculiar ability to think about what isn’t real—yet or maybe ever. To say that many countries now require something is certainly a fact; the national governments of countries require all kinds of things, and that assertion is so obvious that no investigation of that general fact is necessary to prove it. And because that assertion is assumed to be fact, the verb require is in the indicative mood (and is plural because of the plural subject many countries, and is simple present tense because it refers to a perduring truth).
But the verb require is also transitive, and here is where the design of the sentence gets interesting. Transitive verbs require an object, so what is it exactly that many countries require? The sentence states that object in the form of a clause, a group of words with a subject and verb: that one have substantial savings in the bank before retiring there, and so the writer now has to decide what mood—fact, command, or possibility—the verb of this object clause, have, should be. To write one has substantial savings would be to state a fact, and so would be in the indicative mood. To write one have substantial savings, however, would be to state a condition or possibility, and so that verb must be in the subjunctive mood. (The simple subjunctive is identical in spelling to its infinitive form.)
So is it a fact that one indeed has substantial savings in the bank? How could the writer (or the government) know that? No one in particular is being addressed, which is why the indefinite pronoun one is being employed as the subject of the object clause; how, thus, could the fact ever be established? Instead, the statement in the object clause is being rendered as a condition, a possibility, and what is possible is only potential, not actual. Hence, the subjunctive have is necessary in that object clause.
The same construction is at work in this sentence: The customer demanded that the clerk apologize. What is a fact is that the customer demanded something, and so the verb demanded is in the indicative mood. What the customer demanded (the object of that transitive verb) is here again expressed in the form of a clause, that the clerk apologize. Now that customer could yell and pound on the counter all day long, but all that demanding will not necessarily produce the fact of the clerk’s apologizing. In fact, the fact that the clerk hasn’t yet apologized is the reason the customer is getting so excited. It’s a possibility, but not yet a sensible fact, and so the verb apologize must be in the subjunctive mood (its indicative form would be apologizes).
The subjunctive mood was once replete in English (that’s one of the reasons Shakespeare sounds like Shakespeare), but its use has now been reduced considerably. There remain, though, certain constructions like the one we’ve been discussing here that still, well, require or demand it. And how would one ever know that? By reading closely, and then reading closely a little more.