General Norm Change Emil Weydert and Richard Booth

General Norm Change Emil Weydert and Richard Booth Individual 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 family of norm-sets s. t. 1) 2) If is coherent then is the is incoherent

A First Method Construct iteratively • Start with • Then for i = n, …. , 0 – If – else then

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= • Suppose • Then , where:

Example 2 • N= • Suppose • Then , where:

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: NUARY 29……SUBMISSION DEADLINE JANUARY 29……. SUBMISSION DEADLINE JAN