 The causal theory of reference makes it possible that the same term featuring in different theories refers to the same worldly entity. If, for instance, the referent of the term ‘electricity’ is fixed existentially, all different theories of electricity refer to, and dispute over, the same ‘existentially given’ magnitude, viz. electricity; better, the causal agent of salient electrical effects. Hence, the causal theory makes available a way to compare past and present theories and to claim that the successor theory is more truthlike than its predecessors since it says truer things of the same entities. It turns out, however, that the causal theory faces a number of conceptual problems, most notable of which is that it makes referential success inevitable insofar as the phenomena which lead to the introduction of a new theoretical term do have a cause (see Psillos 1999: chapter 11 for a discussion). Philosophers of science have tried to put forward a causal-descriptive theory of reference which makes referential continuity possible whilst allowing room for causal descriptions in fixing the reference of a theoretical  term.[5]