Here is a link which I came across on this site. Should in conditional sentences

It prohibits the usage of 'should' with type 2 and type 3. There are multiple sources which concur with this rule and multiple credible sources which include 'should' with type 2 and type 3.

I don't understand why 'should' cannot be used with the below type 2 examples:

a. If he were to be late again, he should (or would have to) meet me before entering the class.

b. If you met (were to meet) John, you should remind him about the money he owes me.

I would also appreciate your thoughts on the type 3 example: c. If you had stayed with a Mexican friend for years in Dallas, you should have studied Spanish.

  • 1
    should in (a) is fine, but I suggest you avoid the subjunctive form wherever possible: If he is late again, he should see me upon arrival. Note that (b) is invalid with Past Tense met - that would be like changing (a) to If he was late again, he'd be suspended (or worse, ...he'll be suspended). That Simple Past after if does sometimes occur in "uneducated" speech, but you should certainly avoid it if you want to pass exams! Commented Dec 10, 2023 at 18:04
  • ...I'm not convinced English actually has a short, succinct way of referring to how someone should have acted or what they should have done IF some hypothetical situation had arisen in the past (but it DIDN'T), as in your "should have studied Spanish" example. In practice, the words you've written imply the speaker doesn't know whether you met the "precondition" (staying with a friend for years), but he's asserting that if in fact you did, he takes it for granted you will have studied Spanish. Commented Dec 10, 2023 at 18:09
  • I don't think much of "numbered conditionals" anyway (there are too many variations to assign unique numbers to all possibilities). But The type 3 conditional refers to an impossible condition in the past and its probable result in the past,, which is not the meaning of your final example in "standard" English today (we use If that had been true, this would be true, not should). So there you are - your "type 3" is an exotic rare "obligation, duty" context that hasn't been assigned a number! Commented Dec 10, 2023 at 20:20

1 Answer 1


'should' is possible in all conditionals (although conditionals are a poor point of view) but pay attention to the meaning. According to Practical English Usage:

Should can be used to express the deduction or conclusion that something is probable now or in the future: it is expected, normal or logical.

We do not normally use should + infinitive to talk about the past.

However, we can use should have / ought to have + past participle to make guesses or draw conclusions about things which are not certain to have happened.

We can also use this structure to talk about actions which we expect to have been completed by now or at a future time.

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