Source : Webster's Revised Unabridged Dictionary (1913)

Positivism \Pos"i*tiv*ism\, n.
   A system of philosophy originated by M. Auguste Comte, which
   deals only with positives. It excludes from philosophy
   everything but the natural phenomena or properties of
   knowable things, together with their invariable relations of
   coexistence and succession, as occurring in time and space.
   Such relations are denominated laws, which are to be
   discovered by observation, experiment, and comparison. This
   philosophy holds all inquiry into causes, both efficient and
   final, to be useless and unprofitable.

Source : WordNet®

positivism
     n 1: the form of empiricism that bases all knowledge on
          perceptual experience (not on intuition or revelation)
          [syn: {logical positivism}]
     2: a quality or state characterized by certainty or acceptance
        or affirmation [syn: {positivity}] [ant: {negativism}]