The determinacy of computation

Abstract

A skeptical worry known as 'the indeterminacy of computation' animates much recent philosophical reflection on the computational identity of physical systems.On the one hand, computational explanation seems to require that physical computing systems fall under a single, unique computational description at a time. On the other, if a physical system falls under any computational description, it seems to fall under many simultaneously. Absent some principled reason to take just one of these descriptions in particular as relevant for computational explanation, widespread failure of computational explanation would appear to follow. This paper advances a new solution to the indeterminacy of computation. Very roughly, I argue that the computational identity of a physical system is determinate relative to a contextually specified way of regarding that system computationally ---known as a labelling scheme. When a system simultaneously implements multiple computations, it does so relative to different labelling schemes. But relative to a fixed labelling scheme, a physical system has a unique computational identity. I argue that this relativistic conception of computational identity vindicates computational explanation and comports well with computational practice.

Computing in the nick of time

“…For example, in isolation, the very same system may be describable as implementing both an OR and an AND gate (Shagrir, 2001, 2020). Many solutions have been proposed to this problem, including ones that emphasize the importance of the context in which computing devices are embedded (for overview of the available views, see Curtis‐Trudel, 2022; Papayannopoulos et al, 2022). From our vantage point, however, the problem is an artefact of starting‐off with a conception of computing tasks that eschews matters of timing, which is inherently determined by the context in which a device is embedded.…”