New answers tagged auxiliary-verbs
the onus must be on (you who/those who/those that) (has/have) the capability MacMillan dictionary if the onus is on someone to do something, it is their responsibility or duty to do it finedictionary
Shall works as well. It creates both aspects of "should" and "can." "Shall" encompasses an intention that is obliged, much like "should," It also adds the definiteness that the thing will be done, ergo the "can" is necessarily implied. One shall only do something if one can.
The phrase "can and should" conveys the idea that the action is acceptable, and expected. "must" could be substituted for should to give a bit more obligation to the imperative, and the "can and" could be left off to give even more indication that the action is not optional. Otherwise, go to direct imperatives like it is required to do the action.
In moral philosophy there is the concept "ought implies can" (https://en.wikipedia.org/wiki/Ought_implies_can). In other words, you have no moral obligation to do something which you are not capable of doing. So the "can" in "can and should" is in this sense redundant, and you could just say "should" by itself.
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