 However, such asymmetric dependencies among criteria alone will not “explain (away)” either the reality or the appearance of the analytic, since there would appear to be asymmetric dependencies of the proposed sort in non-analytic cases. Natural kinds are dramatic cases in point (see Putnam 1962 [1975], 1970 [1975], 1975). At some stage in history probably the only way anyone could tell whether something was a case of polio was to see whether there was a certain constellation of standard symptoms, e.g. paralysis; other ways (including asking others) asymmetrically depended upon that way. But this wouldn’t make “All polio cases exhibit paralysis” remotely analytic—after all, the standard symptoms for many diseases can sometimes be quite misleading. It required serious empirical research to discover the proper definition of a natural kind term like “polio.” Precisely as Putnam otherwise stressed, methods of testing are so variable it is doubtful that even “single criterion” tests could provide a basis for the identification of the stable meanings of words.