premise: Sherwood Stewart (born June 6, 1946, in Goose Creek, Texas, United States) played amateur and professional tennis in the 1970s and 1980s. Stewart was ranked as high as No. 60 in the world in singles on the ATP Rankings on December 31, 1978, and No. 4 in doubles on January 3, 1983.
hypothesis: Sherwood Stewart was never ranked higher than 50 in the ATP singles rankings. 
reason: While he was ranked 4th it was as a doubles player.  He only reached 60th in the singles rankings. 