General Norm Change

Emil Weydert and Richard BoothIndividual and Collective Reasoning Group

University of Luxembourg

Outline of talk

• The problem of Norm Revision• Basic concepts• Normative states• Basic revision requirements• A first method

The Problem

• normative state + new norms = ??

– What is a normative state?

– How to revise it?

– Revision first, contraction later

The Basic Concepts

• L is some language closed under usual prop. connectives.

• A norm is a conditional with L– “if holds then should hold”

• A set of norms can be coherent or incoherent• Any set of norms induces (conditional)

obligations

Normative States: Ingredients

• Different types of priority between norms:– Temporal (order of introduction)– Commitment (active/inactive)– Explicit (authority)– Implicit (specificity-like)

• We consider only first 2 for now

Normative States

• A normative state N is of the form

– is a prior set of norms– is the sequence of revision inputs

received thus far– is the set of currently active norms– Obligation is induced by N iff it’s induced by

Minimal Requirements on X

• is coherent• • if

– Not necessarily for all i – If N = then not necessarily

The Revision Problem• Given:

– normative state N and coherent norm-set

• Want:– new normative state N

• N = for some new set of active norms • Question: What is ?

Basic Postulates for X’

• By definition of normative state, we must have:– is coherent– (Success)

• Might also expect:– If is coherent then (Conservativeness)

• More?...

A First Method: Some Notation

• Given normative state N = let for i = 0,…,n

• Given 2 norm-sets , set is the family of norm-sets s.t.1) is coherent2) If then is incoherent

A First Method

Construct iteratively• Start with • Then for i = n,….,0

– If then – else

A First Method: Simple Examples

• Examples use a specific definition of “coherence”:– is coherent iff there is no s.t. and can be derived from in System P

Example 1

• N = , where:

• Suppose• Then

Example 2

• N = , where:

• Suppose• Then

Conclusion

• Preliminary framework for Norm Revision• Incorporates temporal and “commitment”

(active/inactive) priorities• Give first method based on maximal coherent

sets, giving active norms “privilege”• Ongoing work….

Norm Change Workshop participants are warmly invited to:

JANUARY 29……SUBMISSION DEADLINE JANUARY 29…….SUBMISSION DEADLINE JANUA