Oppositions and Opposites (2012), p. 160
by Schang, Fabien

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Caption

Piaget’s four quaterns and their logical values in QAS

Logic

Aristotelian family

Classical Sigma-2

Boolean complexity

3

Number of labels per vertex (at most)

1

Uniqueness of the vertices up to logical equivalence

Yes

Errors in the diagram

No

Geometry

Shape

Square (regular)

Colinearity range

0

Coplanarity range

0

Cospatiality range

0

Representation of contradiction

By central symmetry

Vertex description

Conceptual info

No

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

Style

Diagram is colored

No

Diagram is embellished

No

Additional notes

This diagram is flipped, with the subcontrariety at the top edge and the contrariety at the bottom edge.