Human beings have always been specialists, but over the past two centuries division of labor has become deeper, ubiquitous, and much more fluid. The form it now takes brings in its wake a series of problems that are simultaneously philosophical and practical, having to do with coordinating the activities of experts in different disciplines who do not understand one another. Because these problems are unrecognized, and because we do not have solutions for them, we areon the verge of an age in which decisions that depend on understanding more than one discipline at a time will be made poorly. Since so many decisions do require multidisciplinary knowledge, these philosophical problems are urgent.Some of the puzzles that have traditionally been on philosophers'' agendas have to do with intellectual devices developed to handle less extreme forms of specialization. Two of these, necessity and the practical `ought'', are given extended treatment in Elijah Millgram''s The Great Endarkenment. I
