ERRATUM: At https://youtu.be/4kCl_RDRnuY?t=1540 I intended to say, "A disjunction of negations expresses contrariety"; not "sub-contrariety".This video explains complex propositions and how they are expressed in English.Spanish Summer by Audionautix is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/...)Artist: http://audionautix.com/