The simplest notation for logic ever invented

Existential Graphs

by John F. Sowa

Introduction (Prolog)

A mental model is an explanation of how something works in the real world.

It represents a view of the world and relationships among its various parts.

An information model implements a mental model by defining data structures and their relationships.

Logic describes how parts of a model are linked together to make a working information system.

A graph is one way to organize an information model.

In this presentation, John F Sowa shows how to create a graph using natural language and symbols.

Ontomatica shows how to translate Sowa’s human‒readable graphs into machine‒readable code.

Philip Johnson‒Laird argues human reasoning is based on the construction and evaluation of mental models of the world around us.

  • Philip Johnson‒Laird

    Philip Johnson‒Laird is an expert on human cognition and the psychology of language, thinking and reasoning. He is a developer of the mental model theory of reasoning. Johnson‒Laird has shown that people reason by constructing a set of mental models of possibilities, selecting commonalities, and choosing among them.

We build models using information from our senses, but also assumptions and long‐term knowledge from memory as represented in this diagram:

Ontomatica’s domain‐of‐interest is food and drugs. A data‐centric mental model for organizing foods might begin with a layout of a grocery story.

An information model could start with a similar mental model and add data definitions by aisle (broad classes), shelves on an aisle (narrow classes), brands on a shelf, and then characteristic of individual items grouped by equivalence or similarity.

Sowa Summary

Existential graphs (EGs) are an excellent teaching tool.
EG rules of inference are notation‐independent
The same rules may be used for propositional logic, first‐order logic (FOL), and many variations and extensions of FOL.
They may be used with graphic and linear notations, including any subset of natural language that can be translated to FOL.
Peirce claimed that existential graphs represent
a moving picture of the action of the mind in thought
The psychologist Philip Johnson‒Laird agreed
Peirce’s EGs and rules of inference are a good candidate for a natural logic