Television, shows and entertainment will put people's consciousness into a sleeping-mode and destroy their ability to think and understand that, consequently, will affect cultural, educational, political and other aspects of life, which can finally bring the civilization to death.
Neil has a mix of scientific and artistic approach for making predictions inspired by the works of A. Huxley and M. McLuhan; he had degrees and status in media and culture research institutions. But, as a journalist, he investigated the problem using his perception, intuition and ability to sense the trends - then he looked for data or statistic to prove his arguments.
Postman, Neil. 1985. Amusing ourselves to death: public discourse in the age of show business. New York: Viking.