Against Structuralist Theories of Computational Implementation
Michael Rescorla · The British Journal for the Philosophy of Science · 2012
Under what conditions does a physical system implement or realize a computation? Structuralism about computational implementation, espoused by Chalmers and others, holds that a physical system realizes a computation just in case the system instantiates a pattern of causal organization isomorphic to the computation’s formal structure. I argue against structuralism through counter-examples drawn from computer science. On my opposing view, computational implementation sometimes requires instantiating semantic properties that outstrip any relevant pattern of causal organization. In developing my argument, I defend anti-individualism about computational implementation: relations to the social environment sometimes help determine whether a physical system realizes a computation. 1 The Physical Realization Relation 2 Semantics and Computational Implementation 3 Conforming to Instructions 4 Implementing a Computer Program 4.1 The denotational semantics of Scheme 4.2 Worries about intentionality 4.3 Worries about the natural numbers 5 Implementing a Machine Model 6 Bounded Structuralism 7 Triviality Arguments 8 Anti-individualism about Computational Implementation