R-04 · 6 min

The Definitions Problem

Abstract

Most policy disputes are not about rules. They are about what a word meant, to whom, and when.

Learning objectives

01Show how a single undefined term can change every downstream outcome.
02Scope and version definitions independently of the rules that use them.
03Detect definitional collisions across policies.

Concept

Every policy rests on a vocabulary: resident, employee, high-risk, material, critical infrastructure, reasonable effort. These terms look like shared language and behave like private jargon. Two departments applying the same rule with different definitions of the same term will produce contradictory outcomes and both will be following policy.

Four ways definitions break

Implicit definitions: the term is never defined, only used, and meaning accretes through practice.
Competing definitions: the same term is defined differently in two instruments that both apply.
Drifting definitions: the definition changes but downstream rules are not re-examined.
Borrowed definitions: the policy defers to an external source that itself changes without notice.

Definitions as a dependency graph

In a machine-readable policy, definitions are not a glossary section — they are nodes that rules depend on. Changing a definition marks every dependent rule as affected. Scope is explicit: this definition applies within this instrument, for this population, during this period. Where the source text is ambiguous, the ambiguity is recorded as an open question with a named owner rather than resolved silently by whoever implements it.

This is the least glamorous part of policy engineering and the part that determines whether everything downstream holds.

Framework

Definition discipline

01Extract every defined term
02Scope it to the policy that owns it
03Version it independently
04Resolve collisions explicitly
05Bind rules to term versions

Case study

Two meanings of 'employee'

An HR policy and a security policy both use the word 'employee'. One includes contractors; the other does not. Neither document says so. Automated access provisioning inherits both meanings and grants access it should not.

Under definition discipline each policy declares its own scoped term, and the collision surfaces at compile time rather than at incident time.

Exercise

Extract the definitions from a policy you rely on.

01List every term the rules depend on.
02Mark which are defined in the document and which are assumed.
03For each assumed term, find where else in the organisation it is defined differently.

Artifact

definitions

term: employee
scope: hr.leave_policy@3.2.0
includes: [permanent, fixed_term]
excludes: [contractor, agency_worker]
collides_with: security.access_policy#employee