  One might think the conservativeness test is overly complicated, and that all that matters is that the new entities not interfere with the empirical world. If so, then the test would mention only empirical theories not all theories. But, as Matti Eklund (2007) points out, two kinds of entity that are individually non-interfering with respect to the empirical world might interfere with one another. Schiffer is aware of this problem (see his discussion of anti-fictional entities, pp. 55–6), and this is why he turns to the more complicated account.