This word cannot be uttered by a sane man.

If this sentence is changed into the active voice which one is more appropriate and why?

a) A sane man cannot utter this word

b) A sane man will not utter this word

Is there any rule for changing in this type of sentence that the 'modal verb' will be same for both the active and passive voice?

  • There isn't any rule for that. Both sentences are correct, but they don't bear the same meaning. The first one can mean "A sane man is not allowed to/not able to utter this word". The second can mean "A sane man refuses to utter this word". Commented Jun 23, 2018 at 12:09
  • I'd also add "A sane man would not utter this word" to the list of possibly correct interpretations, with an implication that uttering such a word means you're not a sane man in the first place. Commented Jun 23, 2018 at 14:10
  • I think the OP's question are all active, am I wrong here?
    – user17814
    Commented Mar 10, 2019 at 5:01
  • Why are you mentioning modal verbs??
    – Lambie
    Commented Nov 20, 2019 at 20:50

2 Answers 2


If preserving the meaning of the sentence is your objective for what is more appropriate, then you have to pick the one that changes the meaning of the sentence as little as possible.

In this case, that's a) cannot.

If you cannot do something, then you are incapable of doing it. To say will not simply means that you're not going to—not necessarily because of a lack of ability.

Note, however, that changing from the passive voice to the active (or vice versa) will change the tenor of what's being communicated. If mood is more important than meaning (say you're deciding on a sentence to use when writing a book), then using a different word could be more appropriate. But that's an entirely subjective choice.


This word cannot be uttered by a sane man

has the exact same meaning as

A sane man cannot utter this word.

If "cannot" is the modal that fits the meaning, then "will not" is wrong because "will" is not a synonym for "can." Where did you get the idea that changing voice requires changing a modal?

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