Consider the following phrase.
I recommend that you go to the doctor.
Now there are some people who think that there is an elided word there. Consider this:
I recommend that you should go to the doctor.
This really bothered me for some reason. I didn’t want to think about it that way. It seemed like you were trying to cram together two separate thoughts: “I recommend that you do this” and “You should do this.” Those are basically saying the same thing. It seemed like “should” was redundant. I wanted to prove that it was unnecessary.
But it’s a bit more complicated than that. I had to figure out why I didn’t like it based on the structure of the sentence. Usually when we recommend something, the structure is thus:
I recommend [this course of action] or [this thing].
Either way, what you are recommending is a noun, not a verb. Putting “you go” there instead seems weird. To change it to fit, we’d have to make it a gerund.
I recommend you going to the doctor.
In this case, we don’t need “should” because you going is acting as a noun phrase, the object of my recommendation (functioning as the subject). It may not feel natural, but it feels grammatically correct to me. Other normal examples:
I recommended her to the recruiter.
I recommend this type of candy.
The underlined portions are nouns or noun phrases. So to make the original sentence fit this pattern, you change it to a gerund and that’s that. But speaking of “that”…
“That” is the problem. The word that is a subordinating conjunction (specifically, complementizer) in this case and needs to be followed by a full clause. And it turns out that “you go to the doctor” is a full clause. Alone, this clause is in present tense. But in the original sentence, we are talking about the future, and it does need to be indicated by should. You, the subject, should go to the doctor at some point in the future, I think (I recommend). The word go needs to be an infinitive here (following should) instead of a gerund, indicating the future tense, all because of the word that. That tiny word ruined my whole theory.
But the thing is, should is still repetitive with recommend. Obviously you think the person should go to the doctor if you are recommending it. This goes back to what I said at the beginning. It’s two sentences saying the same thing spliced together.
And that’s why the word should is elided at all. It’s important that it is there in the sentence…as an elision. An implied word. You have to recognise that it’s there, but you mustn’t say it in order to avoid redundancy. It’s kind of fun, isn’t it? A super important invisible word. Behind the scenes, pulling all the strings, functioning as a necessary grammatical component of the sentence…
Another way to test this theory is to negate the sentence. Let’s look:
I recommend that he not do this.
Since you need a full clause after that, and “he not do this” can’t stand on its own (in Standard English), you still need the should there.
I recommend that he should not do this.
“He should not do this” can stand on its own. There we go! You need the elided should.
I tried to find another word to use in place of should to test my theory, but there really isn’t one that works in this specific case. In other cases, should can be replaced by must or need to, but it just doesn’t sound right in this case.
I recommend that you must go to the doctor.
That sounds like a command. You have to either be recommending it or commanding it, not both.
I recommend that you need to go to the doctor.
If it’s truly a necessity that the person go to the doctor, you need some sentiment stronger than a recommendation, so just leave out that part entirely.
To be fair, the sentence does sound kind of weird if we say the should, and these other two options satisfy the full-clause rule so it would probably be okay to say that they are the elided words instead of should (as long as you remember to not say them). But if you do say the should in the original sentence, it sounds much less weird than if you say either of the sentences above. But that is probably just an issue of semantics and a discussion for another day.
In any case, it’s funny how I started off trying to get rid of should, but I only ended up proving that it’s necessary! Either way I’m happy that I now have some reasoning to support either one claim or the other. When I first heard of this issue, I wasn’t provided with any reasoning, so I had to come up with my own because it intrigued me.
I’m curious what your thoughts are on this! If I come across something supporting or disproving my claim in my studies, I’ll be sure to update this post accordingly. But if you have any knowledge of this particular issue, or even just an opinion, I’d love to hear it!