Simplify the following text for a Grade 11 native English-speaking person.
Original: Paul Watzlawick PhD ( July 25 , 1921 â `` March 31 , 2007 ) was a theoretician in Communication Theory and Radical Constructivism .
Simplified: Paul Watzlawick ( July 25 , 1921 - March 31 , 2007 ) was an Austrian-American psychologist and philosopher .