Sure-thing principle¶
A decision principle requiring the same action when it is preferred both conditional on an event and conditional on its complement.
Core Idea¶
If action A is preferred to B given E and also given not-E, the sure-thing principle says uncertainty about whether E occurred should not reverse that preference. Partitioning states by an unresolved event reveals dominance that is invariant across every branch, so recombining branches preserves the choice. The abstraction is therefore identified by a declared carrier, a transformation or constraint over that carrier, and an invariant that tells an analyst whether the named structure is genuinely present.
The load-bearing residual is not the broad topic of decision theory. It is the domain-specific identity determined by the conditioning event and its complement exhaust the relevant states and the same pairwise preference holds in both.
Scope of Application¶
Sure-thing principle belongs to decision theory and is useful where the analyst can specify the typed decision theory carrier, defining objects and relations, parameters, conventions, evidence, boundary cases and comparison targets, then evaluate the conditioning event and its complement exhaust the relevant states and the same pairwise preference holds in both. The scope is broad within that domain but bounded by the need for the conditioning event and its complement exhaust the relevant states and the same pairwise preference holds in both. The entry records a descriptive analytical identity; practical use requires the governing domain's evidence, standards, and safety obligations.
Clarity¶
The abstraction clarifies a crowded vocabulary by making the conditioning event and its complement exhaust the relevant states and the same pairwise preference holds in both the center of the account. A claim should name the carrier, the governing operation or relation, the applicable assumptions, and the recognition test. A bare label is insufficient because the name Sure-thing principle can be used for a formal identity, an implementation, or a neighboring result unless carrier and convention are stated.
Manages Complexity¶
Without the abstraction, an analyst must reason directly over many local details: the carrier roles, admissibility assumptions, competing conventions, derived invariants, boundary cases, and proof or validation obligations specific to Sure-thing principle. Sure-thing principle compresses them into the roles in the structural signature. That compression permits comparison across instances without erasing the variables that determine validity. It also exposes which details may be varied safely and which are constitutive.
Abstract Reasoning¶
- Identify the carrier. State what the elements, states, objects, or observations are: the typed decision theory carrier, defining objects and relations, parameters, conventions, evidence, boundary cases and comparison targets. Reject examples whose alleged carrier belongs to a different problem. 2. Lock the constitutive rule. Express the conditioning event and its complement exhaust the relevant states and the same pairwise preference holds in both independently of one notation or implementation.
Knowledge Transfer¶
Knowledge transfers strongly among subfields of decision theory because they reuse the typed decision theory carrier, defining objects and relations, parameters, conventions, evidence, boundary cases and comparison targets, Partitioning states by an unresolved event reveals dominance that is invariant across every branch, so recombining branches preserves the choice., and type the carrier, state every parameter and convention in the definition, test that the conditioning event and its complement exhaust the relevant states and the same pairwise preference holds in both, compare the nearest accepted identity, and report counterexamples, uncertainty, and limiting cases.
Relationships to Other Abstractions¶
Current abstraction Sure-thing principle Domain-specific
Parents (1) — more general patterns this builds on
-
Sure-thing principle is a kind of Rationality Prime
The proposed strict upward parent is
prime:rationality.
Hierarchy path (1) — routes to 1 parentless root
- Sure-thing principle → Rationality → Normativity → Constraint
Neighborhood in Abstraction Space¶
Sure-thing principle sits in a crowded region of the domain-specific corpus (21st percentile for distinctiveness): several abstractions share nearly its structure, so a description that fits it tends to fit its neighbors too.
Family — Algorithms, Proofs & Computational Decisions (25 abstractions)
Nearest neighbors
- Witness set — 0.92
- Invariant estimator — 0.91
- Connected relation — 0.91
- Directed information — 0.91
- Sequential analysis — 0.91
Computed from structural-signature embeddings · 2026-09-08