Mario claims that cognitive science isn't a genuinely autonomous discipline. He makes this claim based on the fact that cognitive science overlaps with issues addressed by other disciplines, and based on the general principle that a genuinely autonomous discipline must have its own domain of inquiry.

Lucy rejects Mario's argument. She points out that Mario believes philosophy is a genuinely autonomous discipline, though he also believes philosophy addresses issues that overlap with other disciplines — beliefs which are inconsistent with the principle he invoked. Lucy then invokes a different principle than Mario's for defining a genuinely autonomous discipline: one with a unique methodology, rather than one with its own unique set of issues of inquiry.

Lucy counters Mario's position by pointing out that Mario has demonstrated other beliefs that directly contradict the principle he asserts. If Mario believes philosophy is a genuinely autonomous discipline, then he can't believe that a genuinely autonomous discipline must have a completely unique domain of inquiry, since he also believes that philosophy examines issues that overlap with other disciplines. So Lucy points out other beliefs Mario has that undermine the principle he suggests for defining a genuinely autonomous discipline, then Lucy suggests a different principle.