Conditionals in English are usually formed by using if with normal word order; but for the three past (subjunctive) forms were, should, and had, it is also possible to express the conditional through subject–auxiliary inversion alone, with no if in the conditional clause.

Does forming conditionals in this manner differ semantically from if-conditionals? Is some aspect of the conditional statement or the conditionality emphasised more in one version than in the other? Or are there differences in how and when they are used? Or are they simply completely interchangeable?

For example:

If I were you, I would try it again
Were I you, I would try it again

If I had seen it, I would have told you
Had I seen it, I would have told you

If you should drink, don’t get behind the wheel
Should you drink, don’t get behind the wheel

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    For me, it's an old fashioned learned use, and it is purely a matter of style. I might use it if I wanted to sound stuffy.
    – Greg Lee
    Mar 16, 2015 at 21:13
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    Had is less stuffy than the others (particular in the more or less set phrase “Had it not been for the fact that…”), and it's also quite common to hear “Should you [choose/wish/want/etc.]” (as in Mission:Impossible: “Your mission, should you choose to accept it…”); but apart from that, my feeling is the same as Greg’s. Mar 16, 2015 at 21:18
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    Why was this marked as a duplicate of a question about “If I was” vs. “If I were”? That's completely unrelated to this question. Mar 17, 2015 at 10:01
  • @Janus Bahs Jacquet Fortunately there are some people like you watchful, but when you are ignored tells me “decision has already been made and it is non changeable “ I think you deserve an answer this site is very helpful site to the extent that it could be used as a source to answer all English questions when the people search for an answer., .Now if they type my question on google or else and it appears as a duplicate with no answer, it does not look good even though there are so many knowledgeable people cooperating and giving their knowledge to the public by using this site ..
    – Saeid
    Mar 18, 2015 at 22:28
  • @Saeid Four people have voted to reopen the question so far—one more vote is needed, then it will be reopened. I’m going to edit your question into more idiomatic English; that will bump it to the top of the list, and a high-rep user will hopefully see it and cast the final vote to reopen. Mar 18, 2015 at 22:32

2 Answers 2


The phenomenon mentioned here is often called Conditional Inversion in the linguistic literature. Here's an interesting paper about it.

One difference between Conditional Inversion and if is that inversion is really only possible with those three verbs, as you note, and hence is usually only found with counterfactuals. Another difference is that inversion doesn't work well with the focus adverb only:

  1. Only if I had thought that he was sick would I have called him.
  2. *Only had I thought that he was sick would I have called him.

Those are my judgements and the judgements of the authors of the paper I linked to, and my guess is that they are in line with modern usage generally, though it would be good to check. The Iatridou & Embick paper gives some more potential contrasts. Their conclusion is that verb-initial conditional clauses can't be focused, and that "The use of inversion is meant to indicate the fact that the truth of the proposition in the antecedent is old [information]".

A side point is that in the recent history of English this type of inversion was possible with a lot more verbs, including could, would, might and did (Denison 1998: 298-300). This might account for the overall rather formal flavour of these examples, as Greg Lee mentioned in his comment.

Still, in a large number of situations the two constructions are completely interchangeable (for me at least).

Ref: Denison, David. 1998. Syntax. In Suzanne Romaine (ed), The Cambridge Grammar of the English Language, vol. 4: 1776-1997, 292-329. Cambridge: Cambridge University Press.

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    Additionally, it may be added that in many other Germanic languages, conditional inversion can be applied to just about any conditional, regardless of what the verb is. On the other hand, an inversed condition can in English be focused (if indeed it counts as focusing—I’m not sure) by a strengthening even (“Even had they not done so…”), which utterly impossible in at least the other Germanic languages I consider myself proficient in. Jul 5, 2015 at 12:35
  • The link to the paper does not seem to work anymore?
    – Matifou
    Nov 20, 2020 at 17:54
  • Thanks Matifou - I’ve updated the link. Nov 20, 2020 at 23:34

As George said earlier, these inversions are interchangeable and my opinion is that it puts more emphasis on the condition than the if-clauses. I'd say one normally uses it to sound more 'academic', to gain points in school essays and to look good and sound smart. The only thing I would add is that you can use 'should' to show a future possibility as well, not just in the example you gave. For instance, you could say:

Should I win the competition, I would donate the money to charity.

If you want to use an if-clause, you don't necessary need to include the 'should'.

If I won the competition, I would donate the money to charity.

To me, they sounds like an aspiration, a dream, or a possibility (which would be stronger in the first case than in the if clause). I would personally use 'Should I get this...' when I'm thinking there's a good chance that might happen. But it's a personal preference, otherwise I'd say they are completely interchangeable (with the exception of only if, but that's a different type of condition).

Hope this helped :)

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    For more certainty, I would use the present in the apodosis at least (which, with if, would require it in the protasis as well): “Should I win the competition, I will donate…” and “If I win the competition, I will donate…”. Jul 5, 2015 at 12:38

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