general norm change emil weydert and richard booth individual and collective reasoning group...

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