I've been noticing that "should have to" is used much more often in formal English than "need" in affirmative sentences and "am/is/are to" in interrogative sentences.

Is it because it implies a stronger urge and a stronger forcedness?

  • If you should have to kill him, do it without hesitation. - is impossible in informal English?
  • You should have to talk to the teacher about taking the test. - is okay in formal English only?

When should we have to use "should have to" and when "need" or "am/is/are to"?

  • Hi there, there's already a question on your phrase "should have to": ell.stackexchange.com/questions/73871/…
    – Puffy
    Sep 6, 2018 at 10:34
  • @Puffy it isn't the same as my question, and not related to this one. Sep 6, 2018 at 10:37
  • "You should have to talk to the teacher" sounds weird and non-fluent to me. if I heard it, I would say, "Wait, why should I have to talk to the teacher?"
    – stangdon
    Sep 6, 2018 at 12:05
  • 2
    I can think of a context where the teacher example would make sense: under current circumstances you won't be required to talk to the teacher, although normally you would be required to do so. You should have to talk to the teacher about X, but .... The emphasis falls on should. Alternatively, the speaker wishes that talking to the teacher were a requirement, although at the current time it is not. You should have to talk to the teacher, yet you don't, and then the emphasis falls on have to.
    – TimR
    Sep 6, 2018 at 12:31

1 Answer 1


"Should" is a modal verb which, among other things, indicates the conditional mood in formal English. I don't believe it implies a stronger urge or force. There is no real difference between "If you should have to kill him", "If you have to kill him" and "If you need to kill him" except the first one automatically sounds like it's being said in Received Pronunciation accent (because it sounds formal).

"Should" lets you do something else though, it lets you drop the "if" but keep the clause conditional. So you could write "Should you have to kill him" and it means the same as the other options.

One thing I want to point out. "Should" isn't replacing "need" in those sentences, "have" is replacing "need". I think "Should you need to kill him" is grammatically fine, but doesn't sound quite right to my ear.

I think your second example sentence is doing something different. Here "should" isn't indicating a conditional, it is indicating an obligation or advice. It's equivalent to "I strongly recommend you talk to the teacher". This is not a formal usage, so I think it would sound fine in informal English. "You need to talk to the teacher" might be a more common way to say it though.

  • +1 for the first part, but I'm not sure of the explanation for the teacher example. Without have to I'd agree. To me it sounds more like "Under normal circumstances, you would be required to talk to the teacher". Dean Jones, can I audit Professor Johnson's course? --You should have to talk to the teacher first, but since she's not returning from sabbatical until a few days before the semester starts, we will make an exception.
    – TimR
    Sep 6, 2018 at 12:19
  • I'll be honest, I had a hard time parsing that second sentence but maybe I'm must tired. I'll have another look in the morning. I like your interpretation, I just think that second sentence is badly in need of some context, italics, punctuation. Just something else to make it clear what it means. But in any case, I don't think it sounds particularly formal. Sep 6, 2018 at 12:27
  • @MichaelFerguson, I'm curious about your usage of "I'm must tired". Is it a colloquial phrase or a typo? Thanks!
    – dan
    Sep 6, 2018 at 13:14
  • @dan Nope, it was a typo and now it's too late to edit. It was supposed to be "maybe I'm just tired". Sep 6, 2018 at 22:21
  • @Tᴚoɯɐuo After looking over it again I think your suggestions here and your comment response to the original question are better than mine. They all fall under the same umbrella definition of should though, so I think I'll leave my answer, and leave your comments to add any more necessary clarification. Sep 6, 2018 at 22:29

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