Sentence:  Traditionally, black American dance students have been consistently steered away from classical ballet and toward the supposedly more “suitable” fields of modern, ethnic or Broadway-chorus dancing. The Harlem Dance Theater performances showed beyond doubt that the practice was based not on rhyme but on prejudiced <WSD>unreason</WSD>. 
Meaning of the word marked with <WSD> tags:  Lack of reason or rationality; unreasonableness; irrationality.