The Modal Equivalence Rules of the Port-Royal Logic (2017), p. 218
by Grey, John

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Caption

Eustachius' diagram of the opposition and equivalence of modal propositions

Logic

Aristotelian family

Classical Sigma-2

Boolean complexity

3

Number of labels per vertex (at most)

4

Equivalence between (some) labels of the same vertex

Yes

Analogy between (some) labels of the same vertex

No

Uniqueness of the vertices up to logical equivalence

Yes

Errors in the diagram

No

Geometry

Shape

Rectangle (irregular)

Colinearity range

0

Coplanarity range

0

Cospatiality range

0

Representation of contradiction

By central symmetry

Vertex description

Conceptual info

No

Mnemonic support (AEIO, purpurea ...)

Yes

Edge description

Style

Diagram is colored

No

Diagram is embellished

No

Is a reproduction of

Sancto Paulo, Eustachius a. 1649. Summa philosophiae quadripartita. Cambridge: Roger Daniel. (p. 105)