# von Wright's 1956 Dyadic Deontic Logic System.

[Hilpinen, 1981, pages 26-27]

## Notes

This system was published by Georg Henrik von Wright in 1956 in a paper
called "A Note on Deontic Logic and Derived Obligation" that appeared
in "Mind".

This system was an effort to cure some of the problems of
his 1951 system.

The basic operator here is a dyadic operator P. von Wright uses
the notation P(r|s) as meaning r is permissible under circumstances s.
I will break with his notation and use P(r,s) instead, as I find that
more readable.

The operator O (obligation) is defined in terms of P in axiom I3 below

von Wright later introduced another dyadic system,
his 1964 system

## Based on

- PC
- Axioms (Following Hilpinen's numbering)
- I1: P(r,s) + P(~r,s)
- I2: P(p&q,r) == (P(p,r) & P(q,r&p))
- I3: O(p,r) == ~P(~p,r)

## Basis for

I'm not aware of any...

## Compare with

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This page was last modified on October 14th, 2005