---
title: "Functionalism"
description: "The position, attributed to Turing and von Neumann, that what a thing is is defined by what it does: a function is a relationship between inputs and outputs, independent of the mechanism that implements it, and therefore \"multiply realizable\" on any substrate that can compute."
type: "glossary-term"
canonical_url: "https://antikythera.wiki/terms/functionalism"
md_url: "https://antikythera.wiki/md/terms/functionalism"
last_updated: "2026-09-06"
site: "Antikythera Wiki"
---

# Functionalism

> A working definition written for this wiki from the reading notes; not Antikythera's own wording. From Antikythera Wiki (https://antikythera.wiki/terms/functionalism), an independent guide to Antikythera's published work.

The position, attributed to Turing and von Neumann, that what a thing *is* is defined by what it *does*: a function is a relationship between inputs and outputs, independent of the mechanism that implements it, and therefore "multiply realizable" on any substrate that can compute. Agüera y Arcas extends it from minds (Putnam's philosophical functionalism, the Turing Test) to organs and organisms — the "Kidney Turing Test" — and to life itself, which becomes a composition of functions. It is the premise behind the claim that a next-token predictor is real rather than counterfeit intelligence. Its main in-corpus challenger is Tripaldi's substrate agency, which holds that substrates shape which functions are possible at all.

## Appears in

- [Substrates Unbound](https://antikythera.wiki/work/journal/substrates) (2025-11-21)
- [What Is Intelligence?](https://antikythera.wiki/work/book/what-is-intelligence) (2025-09-23)
- [What is Intelligence? (Lecture)](https://antikythera.wiki/work/journal/wii-film) (2025-05-10)

_Glossary generated 2026-09-06._