Radical constructivism, thus, is radical because it breaks with convention and develops a theory of knowledge in which knowledge does not reflect an 'objective' ontological reality.

Paul Watzlawick (July 25 1921 – March 31 2007) was an Austrian-American family therapist psychologist communications theorist and philosopher. A theoretician in communication theory and radical constructivism he has commented in the fields of family therapy and general psychotherapy. He was one of the most influential figures at the Mental Research Institute and lived and worked in Palo Alto California until a cardiac arrest at his home in Palo Alto caused his death at the age of 85.