Keeping Aristotle’s Syllogisms Straight

From John Lossee’s A Historical Introduction to the Philosophy of Science:

Type Statement Relation
A All S are P S wholly included in P
E No S are P S wholly excluded from P
I Some S are P S partially included in P
O Some S are not P S partially excluded from P

Also remember that there are three valid syllogisms with first premise “All F are G,” and three with first premise “Some F are G.” There are three more with first premise “All F are G” that are not valid, but become so if the additional premise “There are F” is added.

All F are G

All G are H

All F are H

Some F are G

All G are H

Some F are H

All F are G

All G are H

Some F are H

(There are F)

All F are G

No G are H

No F are H

Some F are G

No G are H

Some F are -H

All F are G

No G are H

Some F are -H

(There are F)

All F are G

No H are G

No F are H

Some F are G

No H are G

Some F are -H

All F are G

No H are G

Some F are -H

(There are F)

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One thought on “Keeping Aristotle’s Syllogisms Straight

  1. Dude! Where are the Venn diagrams? Boo. I want Venn Diagrams. But, I do enjoy the occasional run through of logical exercise. Thanks!

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