can not choose but

from The Collaborative International Dictionary of English v.0.48

Choose \Choose\, v. i.
   1. To make a selection; to decide.
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            They had only to choose between implicit obedience
            and open rebellion.                   --Prescott.
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   2. To do otherwise. "Can I choose but smile?" --Pope.
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   {Can not choose but}, must necessarily.
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            Thou canst not choose but know who I am. --Shak.
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