Examples of this sort notwithstanding, it is often claimed that Turing’s original characterization of effective computability provides a template for a more general analysis of what it could mean for a function to be computable by a mechanical device. For instance,  Gandy (1980) and Sieg (2009) argue that the process by which Turing originally arrived at the definition of a Turing machine can be generalized to yield an abstract characterization of a mechanical computing device.   Such characterizations may in turn be understood as describing the properties which a physical system would have to obey in order for it to be concretely implementable.  For instance the requirement that a Turing machine may only access or modify the tape cell which is currently being scanned by its read-write head may be generalized to allow modification to a machine’s state at a bounded distance from one or more computational loci.  Such a requirement can in turn be understood as reflecting the fact that classical physics does not allow for the possibility of action at a distance.