difference - "Ought" vs "Should"

I found that Should, when compared to Ought has some additional uses, in particular replacing "would" or similar, as a neutral joint of sentences, but I'm interested in differences in their fundamental meaning:

used to indicate obligation, duty, or correctness, typically when criticizing someone’s actions

Do they differ in subtle ways, like one being more official or feeling archaic or something like that?

Answer

I must disagree with both user37324 and NOAD.

A recent survey of literature and corpus study¹ on this topic shows clearly:

• that the factors favouring choice of ought to over should are syntactical rather than semantic, and


• that ought to is found more often in speech than in writing, but


• in all contexts, should is preferred, by factors ranging (depending mostly on syntactic context) from 1.9 to 12.6 to 1.

These findings for British English coincide with my own impressions of American use, and with the quantitative findings of American corpus studies. I do not hesitate to assert that the two terms are synonymous. Should may be used in any context where ought to may be used.

And since should is far more frequent, I believe that a Learner may safely eliminate ought to from his vocabulary altogether; using should rather than ought to will never be wrong—unless the Learner must conform to a contrary opinion expressed by an examiner or academic advisor!

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¹Cappelle, Bert and Gert Desutter. 2010. ‘Should vs. Ought to’. In: Bert Cappelle and Naoaki Wada (eds.), Distinctions in English Linguistics, Offered to Renaat Declerck. Tokyo: Kaitakusha, 92-126.