Arguing for Frege's fundamental principle

Saul Kripke's puzzle about belief demonstrates the lack of soundness of the traditional argument for the Fregean fundamental principle that the senten ces 'S believes that a is F' and 'S believes that b is F' can differ in tru th value even if a = b. This principle is a crucial premise in the traditio nal Fregean argument for the existence of semantically relevant senses, ind ividuative elements of beliefs that are sensitive to our varying conception s of what the beliefs are about. Joseph Owens has offered a new argument fo r this fundamental principle, one that is not subject to Kripke's criticism s. I argue that even though Owens' argument avoids Kripke's criticisms, it has other flaws.