Brian Cantwell Smith
on "What Is Computation?"

Smith, Brian Cantwell (2002), "The Foundations of Computing", in Scheutz, Matthias (ed.), Computationalism: New Directions (Cambridge, MA: MIT Press): 23-58.

1. The major question in the philosophy of computer science is:
   • What is computation?

   and the answer is that it is a lot more than the theory of Turing machines.

2. CS is an empirical endeavor.

3. 9 Theses about Computation:
   • (C2) CS needs a full theory of semantics and intentionality.

   • (C1) Therefore (because none of the following provide such a theory), none of the current & different theories of computation succeed:
     • formal symbol manipulation
     • effective computability
     • execution of algorithms, or rule following
     • calculation of functions
     • digital state machines
     • information processing
     • physical symbol systems

   • (C3) Formal symbol manipulation's separation of the syntactic and semantic domains is misleading;
              they are "participatory" (i.e., they intersect)

   • (C4) TMs don't use marks to represent numbers;
              they use numbers to represent marks!
     • Corollary:
       The theory of computation is "a theory of how...patches of the world in one physical configuration [can] change into another physical configuration" (p.42)

   • (C5) I.e., the mathematical theory of computation is a mathematical thoery of the flow of causality

   • (C6) Computation is not formal in any of the following senses of "formal":
     • anti-semantic
     • syntactic
     • deterministic, or well-defined (i.e., not vague)
     • mathematical
     • analytic method

   • (C7) CS needs a full theory of ontology
     • For a beginning, see:
       Smith, Brian Cantwell (1996), On the Origin of Objects (Cambridge, MA: MIT Press).

   • (C8) Computers are not natural kinds
              & there can be no theory of computation

   • (C9) Therefore, the existence of computation is extremely important,
              because any theory of it will be a theory of intentional artifacts, hence a theory of everything!