Theorist: To be capable of planned locomotion, an organism must be able both to form an internal representation of its environment and to send messages to its muscles to control movements. Such an organism must ttherefore have a central nervous system. Thus, an organism incapable of planned locomotion does not have a central nervous system. The theorist's argument is flawed in that it ['takes for granted that adaptations that serve a biologically useful purpose originally came about for that purpose', 'presumes, without providing justification, that an internal representation of its environment can be formed by an organism with even a rudimentary nervous system', "presumes, without providing justification, that planned locomotion is the only biologically useful purpose for an organism's forming an internal representation of its environment", "confuses a necessary condition for an organism's possessing a capacity with a sufficient one"]