 The simple mapping account turns out to be very liberal: it attributes many computations to many systems. In the absence of restrictions on which mappings are acceptable, such mappings are relatively easy to come by. As a consequence, some have argued that every physical system implements every computation (Putnam 1988, Searle 1992). This thesis, which trivializes the claim that something is a computing system, will be discussed in Section 3.1. Meanwhile, the desire to avoid this trivialization result is one motivation behind other accounts of concrete computation.