Let’s look again at conditional sentences because they can confound even the most aspiring of writers. A student of mine wants to know whether the verb in the following sentence should be receive, not received: If he received my email, tell him to reply. How can we use the past tense, he argues, when we don’t know whether something has really happened. It’s a smart question, and we should remember that grammar doesn’t answer to our ears. If something sounds correct, that doesn’t necessarily mean it is correct. Then again, maybe it is.
We should first understand that what we are about to examine is called a conditional sentence because we have two clauses, one of which, beginning with the conjunction if, sets down the condition on which a result, stated in the other clause, will occur. The if-clause is called the antecedent, and the result clause (sometimes beginning with then) is called the consequent. What is difficult but essential to understand is that a conditional sentence is asserting only a connection between the ideas in the two clauses, not necessarily the fact of either clause. This is very slippery business, but we’ll be on solid ground shortly.
Now of course there isn’t only one way in which conditions and results can be connected. I can say, for example, that I haven’t looked outside yet this morning, but I can tell you one thing: if it rained last night, the sidewalk is wet. I have no idea whether it rained last night, and I’m not saying it did. What I am saying, though, is that there is an inevitable and factual connection between the idea of its raining and the idea of the sidewalk’s being wet. It’s a lockstep, inevitable relationship. Grammarians call this a logical condition, and the requirement for such a statement is that the verb in the antecedent be in the present, past, or perfect indicative. Why the indicative mood? Because the writer wants to assert a result on the presumption that the antecedent is true.
One eminent grammarian, George Curme, says in his English Grammar that in such a logical conditional sentence, we are “recognizing as a practical working basis the reality of state or fact, but not finally committing ourselves to this view.” Now that is exactly what is going on in our example as it stands. If he received it means on the assumption that he did in fact receive my email, tell him then to reply. The writer has no more idea of whether it is a fact that the person received the email than I do about whether it rained last night. But on the presumption of those ideas as facts, things will inevitably result: the demand that he reply and a wet sidewalk. So the verb received both sounds right and is in fact correct.
Would that we could end this discussion of conditional sentences here, but my student’s question has not let sleeping dogs lie. When he suggests that the verb should rather be receive, he is disturbing the slumbering subjunctive. The present tense of the subjunctive mood of a verb happens to look just like the infinitive form in all persons and numbers, so to say if he receive is in fact correct, but quite literary, English; it is a form of the language we now see for the most part only in literature of another age. Using the subjunctive like this in the antecedent clause of our example creates an entirely different kind of conditional sentence, something grammarians call an ideal condition. Such statements do not presume fact (so the indictive mood is ruled out), but rather present a thought as merely a conception or piece of speculation; and when the idea behind a thought remains theoretical, and not presumed to be real, the subjunctive is necessary. To say if he receive it, tell him to reply means, then, something like this: on the theory that he received it, or if it might be the case that he received it, tell him to reply. The writer doesn’t feel he can even presume the fact of the antecedent (maybe he’s been having trouble with his computer and others have not received his emails), so the indicative mood can’t be used. That leaves the subjunctive and the ensuing ideal condition. One could write like that, but your neighbor would probably be Shakespeare.
It’s a lot, I know, but so are the subtle distinctions our minds can make. The grammarian Curme says that the subjunctive is “a bit of older English not suited to either our practical or our scientific needs.” He’s referring to some peculiar forms and uses of the subjunctive, but not all. We still and must use the subjunctive in yet a third kind of conditional statement called contrary-to-fact, which we can see in a sentence like this, the truth of which will be obvious enough: if I were to continue, this post would be too long.