 Can it happen that the referring expressions ‘a’ and ‘b’ refer precisely in the identity sentence ‘a=b’ without that sentence being determinately true or false? Here is one version of an argument, due to Gareth Evans and Nathan Salmon, that is supposed to show that it cannot (Evans 1978, Salmon 1981). Let ‘Ip’ mean: it is indeterminate whether p, that is p is neither determinately true nor determinately false, and let ‘Dp’ mean: it is determinate that p. We have: