---
title: "A Logical Calculus of the Ideas Immanent in Nervous Activity"
authors:
  - "Warren S. McCulloch"
  - "Walter Pitts"
year: 1943
venue: "Bulletin of Mathematical Biophysics"
arxiv: null
doi: "10.1007/BF02478259"
source: "https://doi.org/10.1007/BF02478259"
topics:
  - neural-nets
  - mcculloch-pitts
  - automata
  - logic
seed_rank: 565
seed_batch: "foundations-greats-2026-08-13"
reviewed: "2026-08-13"
pool: "agents"
relevance_score: 10
lineage: foundations-of-computing
cites:
  - title: "How We Know Universals: The Perception of Auditory and Visual Forms"
    url: "https://doi.org/10.1007/BF02478291"
    year: 1947
    arxiv: null
    doi: "10.1007/BF02478291"
see:
  - "566-how-we-know-universals-the-perception-of-auditory-and-visual"
---

# A Logical Calculus of the Ideas Immanent in Nervous Activity

## One-sentence takeaway

McCulloch and Pitts prove that networks of idealized threshold neurons can realize any propositional formula and, with loops, a wide class of temporal predicates.

## Why it matters here

Von Neumann's EDVAC "organs" language and every later neural/agent net sit on this identification of brains with computing devices.

## Key ideas

- A neuron fires all-or-none when the weighted sum of inputs exceeds a threshold; inhibition is an absolute veto in the original model.
- Combinational nets compute Boolean functions; cycles give memory and a calculus of time-delayed propositions.
- Any finite automaton — and, they argue, any Turing-computable behavior with a tape — can be embodied in such a net.
- The paper is the 1943 founding text of neural computation, published in *Bulletin of Mathematical Biophysics*.
- Pitts–McCulloch 1947 extends the same nets toward invariant perception.

## Caveats

## Links

- DOI: [10.1007/BF02478259](https://doi.org/10.1007/BF02478259)
- URL: https://doi.org/10.1007/BF02478259