I doubt; therefore, I might be

Speranza

 

Grice refers, somewhere in an early essay in the WoW (Way of Words) to Descartes's cogito.

This one at

 

 

http://answers.yahoo.com/question/index?qid=20090316185808AA3FydW

 

-- as per subject line -- might count as its modalised version, which may survive a symbolic translation, or other.

 

Cheers.