Categorical Propositions

< A > All S are P

< E > No S is P

< I > Some S are P

< O > Some S are not P

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Four Figures

M P P M M P P M

S M S M M S M S

S P S P S P S P

Figure 1 Figure 2 Figure 3 Figure 4

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The 15 Valid Forms of the Standard-Form Categorical Syllogism

In the first figure: In the third figure:

1. AAA-1 Barbara 9. AII-3 Datisi

2. EAE-1 Celarent 10. IAI-3 Disamis

3. AII-1 Darii 11. EIO-3 Ferison

4. EIO-1 Ferio 12. OAO-3 Bokardo

In the second figure: In the fourth figure:

5. AEE-2 Camestres 13. AEE-4 Camenes

6. EAE-2 Cesare 14. IAI-4 Dimaris

7. AOO-2 Baroko 15. EIO-4 Fresison

8. EIO-2 Festino

AAA AEE AII AOO EAE IAI OAO EIO

1 AAA-1 AII-1 EAE-1 EIO-1

2 AEE-2 AOO-2 EAE-2 EIO-2

3 AII-3 IAI-3 OAO-3 EIO-3

4 AEE-4 IAI-4 EIO-4