Led by Boethius Simulacrum
About this course
The centre of the school. Module 4 gave inference from one proposition; this gives inference from two, where two premises sharing a term yield a conclusion neither of them contains.
Aristotle's definition is worth having exactly: a syllogism is a discourse in which, certain things being posited, something other than what is posited follows of necessity from their being so. Three clauses, each excluding something. The conclusion must be new — restating a premise is not concluding. It must follow of necessity — not probably. And it must follow from the premises alone, with nothing smuggled in.
The module's central fact is a discovery rather than an apparatus, and it should produce some surprise: validity is entirely a matter of form. Every M is P; every S is M; therefore every S is P — substitute anything at all for the letters, and if the premises are true the conclusion is. The reasoning never consults what the terms mean. That is Aristotle's discovery and the foundation of every formal logic since.
Sixty-four moods across four figures gives 256 combinations, of which twenty-four are valid. You will not memorise twenty-four. You will learn the seven rules that separate valid from invalid, so that any syllogism can be tested and the twenty-four derived. The medieval mnemonic verses — Barbara, Celarent, Darii, Ferio — come afterwards, deliberately: a student with the verses alone has a lookup table, and a student with the rules can always work it out.
The module ends with enthymemes, because nobody argues in syllogisms. Real arguments suppress a premise, and the suppressed premise is very often exactly where the disagreement lies while both parties argue about the stated one.
Taught in English; sources quoted in Latin and Greek.
Led by Boethius Simulacrum
The question
Eight sittings. You begin by putting a sound argument beside an
Outcome
The student can identify the figure and mood of any categorical
Sub-units
Practice scenarios
A committee is defending a decision. Their reasoning: *We want candidates who will stay. People who have stayed in previous roles will stay. This candidate stayed in her previous role. So she will stay.* One member objects that this is circular. Another objects that it is invalid. A third says it is fine and the dissenters are being difficult. They have asked you to say who is right, and the meeting is running late.
Your goals