 However, even if rigid application evades the above difficulties, it has its limitations. One commonly noted problem is this: consider identity statements like ‘Water = H2O’, or ‘Red light = light with wavelength 680 nm’. Rigidity is apparently supposed to guarantee the necessity, in case of truth, of identity statements like these. Typically, fans of rigid application rewrite identity statements to have this form: ‘Anything is (an) F if and only if it is (an) F′’. But many philosophers, including proponents of rigid application, have pointed out that it could be the case for two general terms F and F′ that, (i) necessarily, every F is essentially F and every F′ is essentially F′, so that F and F′ are rigid appliers and (ii) in the actual world, ‘Anything is F if and only if it is F′’ is true, even though (iii) God might have created an F that is not an F′. In that event, ‘Anything is F if and only if it is F′’ comes out true with respect to the actual world but not necessarily true (for an attempt to get around this difficulty, see Gómez-Torrente 2006).