Consider the following type of sentence:

It is kind/nice/cruel/considerate of you to do X.

I understand that the preposition used there should always be 'of,' not 'for.'

Now how would we extend that pattern to the following:

  1. It is decent [of you or for you] to do X?

  2. It is smart [of you or for you] to do X?

I believe that the first sentence continues the pattern above and should take 'of,' while the second might be better with 'for'?

Is there any general rule or pattern to apply to this type of sentence to determine which preposition to use? For example, it seems like the adjectives which take 'of' express connotations of gratitude (as with kind, nice etc.) or the opposite (as with cruel). 'Smart,' on the other hand, which seems like it would fit better with 'for' than with 'of,' does not carry connotations of [gratitude/obligation/the inverse] on the part of the speaker towards the person described as 'you.'

PS. This question does not request for any proofreading: it is only all about the usage of 'of' and 'for' in case of the adjectives like properties or qualities of a person that is described as nice, kind, ..., and/or decent, etc. , especially of the usage of 'decent'.

  • 1
    decent of, but smart for, sounds most idiomatic in my opinion. I'm not sure why! :D Jun 28 at 18:25
  • 1
    Maybe it's the words that express gratitude ('decent,' 'kind' etc.) or the opposite (as for 'cruel') on the part of the speaker towards the subject ('you') that should take 'of,' while other concepts take 'for'? 'Smart' doesn't connote gratitude or its inverse, so you can say 'for' instead of 'of' there, but use 'of' for all the rest. I don't know if there is any definite rule for this though; I'm just going by what sounds right and guessing at the pattern. Nice question, +1! Jun 28 at 18:29
  • What do you think of the suggested edit to your question? If you believe it improves the post and doesn't conflict with your original intent, you can approve the edit so that it is visible to the community. Otherwise, feel free to reject it (or the reviewers will later). Jun 28 at 21:34
  • 3
    "Decent of you to do that" indicates that doing the act reflects the addressee's niceness. In general, it describes an act that demonstrates some quality of a person. If someone has done something smart, "it was smart of you to do that" would be fine (@QuackE.Duck). "Smart for you to do that" implies advice: "it would be a good idea for you to do that; it would be smart for you to do that."
    – phoog
    Jun 29 at 12:21
  • 1
    @QuackE.Duck Yes, that's true. His comment deserves posting as an answer.
    – gomadeng
    Jun 29 at 17:57


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