Mechanistic Computation and its Problems: An Abstract Solution

Luke Kersten

LanCog, University of Lisbon

3 March 2023, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão (Departamento de Filosofia)

Abstract: The mechanistic account of computation (or MAC) maintains that computational implementation is best explicated within a mechanistic framework. A physical system is said to implement a computation only if it processes medium-independent vehicles in virtue of being a functional mechanism. Recently, a number of objections have been raised to MAC, including the “decomposition”, “abstraction”, “generality”, and “hierarchy” problems. These challenges threaten to undermine MAC’s status as a workable theory of implementation. The aim of this paper is to shore up MAC’s conceptual foundations by responding to each. After unpacking the four problems, I outline a recent proposal from Kuokkanen (2022a) which argues that MAC can be rescued by employing a distinction between “vertical” and “horizontal” abstraction. I argue that, while promising, Kuokkanen’s proposal comes at too high a price, requiring MAC to sacrifice its claims on “extensional adequacy”. In response, I outline what I call the “computation-as-abstracta” view. I suggest that thinking of computation as a form of abstracta not only helps to dissolve the four problems but also provides a way of retaining extensional adequacy in the process. I conclude by taking up two further problems recently articulated by Shagrir (2022) and Kuokkanen (2022b).