von Wright's 1951 Deontic Logic System.

[Hilpinen, 1981, pages 8-12]

Notes

This system was published by Georg Henrik von Wright in 1951 in a paper called "Deontic Logic" that appeared in "Mind".

This system uses a modality "O", where Op is taken as meaning p is Obligitory.

This system uses a modality "P", where Pq is taken as meaning q is Permissible.

He later published his Dyadic 1956 system partly to overcome the weaknesses of this system.

He also published a Dyadic System in 1964

Based on

• PC
  • Modus Ponens
  • Uniform substitution
• Axioms (Hilpinen calls these C1-5, but EVERYONE uses C1-5 for something different so:)
  • vC1: Oq == ~P~q
  • vC2: Pq + P~q
  • vC3: P(q+r) == Pq + Pr
  • vC4: O(q&~q) is not valid. ~P(q&~q) is not valid. (The principle of deontic contingency)
  • vC5: If q and r are logically equivalent, Pq and Pr are logicically equivalent.

Basis for

I'm not aware of any...

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This page last updated October 14th, 2005