Why the Logical Hexagon? (2012), p. 79
by Moretti, Alessio

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Caption

Sauriol’s demonstration of Blanché’s incompleteness

Legend

Logic

Aristotelian family

Non-Sigma

Boolean complexity

4

Number of labels per vertex (at most)

1

Uniqueness of the vertices up to logical equivalence

Yes

Errors in the diagram

No

Geometry

Shape

Hexagon (regular)

Colinearity range

0

Coplanarity range

4

Cospatiality range

0

Representation of contradiction

N.A.

Vertex description

Conceptual info

Yes

Mnemonic support (AEIO, purpurea ...)

No

Form

none

Label type

symbolic

Symbolic field

logic

Contains partial formulas or symbols

No

Logical system

propositional logic

Edge description

Contains definitions of relations

No

Form

solid lines

,

none

Has arrowheads

Yes

Overlap

No

Curved

No

Hooked

No

As wide as vertices

No

Contains text

No

Label type

none

Style

Diagram is colored

No

Diagram is embellished

No

Additional notes

The negation closure of this diagram is a classical sigma-7.