Of the 256 forms you met in Figure, only fifteen pass every rule and the Venn test on the modern reading. Medieval students memorized them with names whose vowels spell the mood.
| Figure 1 | Figure 2 | Figure 3 | Figure 4 |
|---|---|---|---|
| Barbara (AAA) | Cesare (EAE) | Disamis (IAI) | Camenes (AEE) |
| Celarent (EAE) | Camestres (AEE) | Datisi (AII) | Dimaris (IAI) |
| Darii (AII) | Festino (EIO) | Bokardo (OAO) | Fresison (EIO) |
| Ferio (EIO) | Baroko (AOO) | Ferison (EIO) |
Key idea
A form is valid on the modern reading exactly when it is one of these fifteen. The first three vowels of each name give the mood: Barbara is AAA, Celarent is EAE, Ferio is EIO.
Why it works
Validity belongs to the form, so a short list of forms covers every valid syllogism ever written. Each name was checked once, and every argument with the same mood and figure inherits the result. You can confirm any entry with a Venn diagram or the rules; the names only save you the work.
Worked examples
Worked example: Name the form
What is the name of: "All runners are early risers. Some runners are readers. So some readers are early risers."?
- Major premise "All runners are early risers": A. Minor "Some runners are readers": I. Conclusion: I. Mood AII.
- The middle term runners is the subject of both premises: figure 3.
- AII-3 is Datisi.
Answer: Datisi
Worked example: From the name
Write Camestres with S, P and M.
- The vowels a, e, e give AEE. Camestres is in figure 2 (P–M, S–M).
- Major: All P are M. Minor: No S are M. Conclusion: No S are P.
Answer: All P are M / No S are M / ∴ No S are P
Common mistake
Learning the names without the forms. A name is useful only if you can read its mood from the vowels and know its figure. Check: from "Ferio", can you write the three lines with S, P and M? (No M are P / Some S are M / ∴ Some S are not P.)