One of the first times we hear that Sondra, the Huxtables' college-aged daughter attends Princeton University.
At the same time, Cliff went to Hillman because his wife-to-be was going, was worried about losing Clair to other men. However, in later seasons, Cliff is 4 years older than Clair, so that can't be right. And if that's the case and they were dating when Cliff was in high school, that means Clair would have been at least 13 or 14 when they first started dating.
Earle Hyman who plays Bill Cosby is 11 years older than him