premise: David Plotz (born January 31, 1970) is an American journalist and is currently the CEO of "Atlas Obscura", an online magazine devoted to discovery and exploration. A writer with "Slate" since its inception in 1996, Plotz was the online magazine's editor from June 2008 until July 2014, succeeding Jacob Weisberg.
hypothesis: Weisberg was born January 31, 1970.
reason: There was no date given for Jacob Weisberg's birthday, so while it is unlikely he has the same birthday as David Plotz, we don't know for sure.  I think this was difficult for the system because it is the same date as Plotz, but Weisberg's birth date was not given.