 Those who deny that there are any perfectly natural properties (e.g. on the grounds that for every property we can find a more natural one, or on the grounds that some magnitudes  (§3.5)  are more natural than any properties) will presumably reject the right-to-left direction of  Duplication,  to avoid the absurd result that any two objects with equally many parts are duplicates. This need not, however, put paid to the program of defining duplication in terms of naturalness. For example, Langton and Lewis  (1998)  suggest a quite different definition in terms of ‘more natural’: for details, see §3.3 in the entry on  intrinsic vs. extrinsic properties.[17] 