Source : Webster's Revised Unabridged Dictionary (1913)

Antinomy \An*tin"o*my\ (?; 277), n.; pl. {Antinomies}. [L.
   antinomia, Gr. ?; ? against + ? law.]
   1. Opposition of one law or rule to another law or rule.

            Different commentators have deduced from it the very
            opposite doctrines. In some instances this apparent
            antinomy is doubtful.                 --De Quincey.

   2. An opposing law or rule of any kind.

            As it were by his own antinomy, or counterstatute.
                                                  --Milton.

   3. (Metaph.) A contradiction or incompatibility of thought or
      language; -- in the Kantian philosophy, such a
      contradiction as arises from the attempt to apply to the
      ideas of the reason, relations or attributes which are
      appropriate only to the facts or the concepts of
      experience.

Source : WordNet®

antinomy
     n : a contradiction between two statements that seem equally
         reasonable