Indefinite proof and inversions of syllogisms

Roy Dyckhoff

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
120 Downloads (Pure)


By considering the new notion of the inverses of syllogisms such as Barbara and Celarent, we show how the rule of Indirect Proof, in the form (no multiple or vacuous discharges) used by Aristotle, may be dispensed with, in a system comprising four basic rules of subalternation or conversion and six basic syllogisms.
Original languageEnglish
Pages (from-to)196-207
Number of pages12
JournalBulletin of Symbolic Logic
Issue number2
Early online date25 Jul 2019
Publication statusPublished - 2019


  • Deduction
  • Syllogism
  • Indirect proof


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