premise: Gray Cowan Boyce (19 February 1899 - 14 May 1981) was an American medieval historian and historical bibliographer whose masterwork was his five volume "Literature of Medieval History, 1930-1975: A Supplement to Louis John Paetow's "A Guide to the Study of Medieval History"" (1981).
hypothesis: Gray Boyce lived through both world wars.
reason: The context says that Gray Boyce was borned in 1899, and died in 1981. So it is definitely correct to say that he lived through both world wars 1 & 2. The system may not understand that dates of the world wars