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Synonyms for Positivism (same or very similar meaning)

WordNet sense 1 (the form of empiricism that bases all knowledge on perceptual experience (not on intuition or revelation)):
logical positivism

WordNet sense 2 (a quality or state characterized by certainty or acceptance or affirmation and dogmatic assertiveness):
positiveness, positivity

From the ODE community, based on WordNetadd/edit