Source : Webster's Revised Unabridged Dictionary (1913)

Positiveness \Pos"i*tive*ness\, n.
   The quality or state of being positive; reality; actualness;
   certainty; confidence; peremptoriness; dogmatism. See
   {Positive}, a.

         Positiveness, pedantry, and ill manners. --Swift.

         The positiveness of sins of commission lies both in the
         habitude of the will and in the executed act too; the
         positiveness of sins of omission is in the habitude of
         the will only.                           --Norris.

Source : WordNet®

positiveness
     n : characterized by dogmatic assertiveness [ant: {negativeness}]