An Enlightenment Problem for Millianism

According to a Millian theory of names, co-referring names are intersubstitutable salva veritate in all contexts, including the that-clauses of belief reports. This leads the Millian to famously argue, among other things, that if Lois Lane believes that Superman can fly then she also believes that Clark Kent can fly. Although the Millian provides an ingenious account that explains our strong anti-substitution intuitions in such cases, this paper argues that the Millian account leads to a new problem of enlightenment in identity reports. Specifically, a believer A may come to discover that two names refer to the same individual S, but whether A is enlightened about the identity of S will depend on the number of guises through which A holds contradictory beliefs about S.