Dialectical thought understands the critical tension between "is" and "ought" first as an ontological condition, pertaining to the structure of Being itself. However, the recognition of this state of Being its theory intends from the beginning a concrete practice. Seen in the light of a truth which appears in them falsified or denied, the given facts themselves appear false and negative.
Herbert Marcuse (2012). “One-Dimensional Man: Studies in the Ideology of Advanced Industrial Society”, p.133, Beacon Press