---
slug: cheap_talk
name: Cheap Talk
one_liner: "Costless, non-binding communication whose credibility rests not on the cost of the message but on the alignment of interests between sender and receiver: when preferences align, even free unverifiable words transmit real information; when they conflict, cheap talk decays into uninformative babbling."
type: prime
schema_version: 2
status: density_v2_draft
categories: [structural, economic, social]
origin_domain: game_theory
alternate_origin_domains: [economics, political_science, organizational_theory, evolutionary_biology]
aliases: [costless_signaling, non_binding_communication, pre_play_communication, babbling_equilibrium, just_words]
related: []
solution_archetypes: []
review_flags:
- "OPERATOR-DERIVED (op-14 lattice/symmetry completion) — the costless pole of the communication-game family, obtained by completing the lattice against the corpus's `signaling` (the COSTLY pole / Spence). Where costly signaling earns credibility from the cost of the message (separating by who-can-afford-it), cheap talk is costless and non-binding, and earns credibility from the ALIGNMENT of interests between sender and receiver. Discovered 2026-07-04. MODERATE-STRONG hold (verified absent from corpus; canonical construct — Crawford & Sobel 1982; Farrell & Rabin 1996). STATUS: HOLD pending owner keep/cut."
- "Created 2026-07-04; STUB ONLY (frontmatter + Core Idea + Notes). SI/SF/similarity are PROPOSER ESTIMATES pending triangulation. Body sections (Structural Signature onward) NOT written."
- "Phase-C action: re-similarity-check vs `signaling` (the costly-pole sibling), `screening`, `coordination`, `common_knowledge`, and any communication primes; confirm it is the genuine costless-pole complement (credibility from interest-alignment, not message cost) and not merely a restatement of signaling or coordination; draw a sibling/lattice edge to `signaling` at incorporation (two-pole {costly, costless} communication-game family); write a v1 draft and sync the one_liner across v1/v2 per CLAUDE.md before merge."
substrate_independence:
  composite_substrate_independence: 3
  domain_breadth: 4
  structural_abstraction: 4
  transfer_evidence: 4
  reasoning: 'The bare structure — costless, non-binding messages whose information content is a function of how aligned the sender''s and receiver''s interests are, sliding from a fully-revealing equilibrium under alignment to a babbling (uninformative) equilibrium under conflict — is a genuinely substrate-neutral form. It recurs wherever an agent can emit a free, unverifiable message that another agent may act on: pre-play communication in games, non-binding diplomatic statements, advice and persuasion, organizational communication down and across hierarchy, focal announcements that coordinate expectations, and animal signals among kin or allies with aligned interests. domain_breadth is 4 (strong spread across game theory, diplomacy, organizations, and biology, though the family is somewhat tighter than the most universal primes). structural_abstraction is 4 because the core is a pure statement about a credibility mechanism — alignment-contingent information transmission at zero message cost — requiring no economic substance to hold, staying just short of 5 because "interests" and "information" carry a mild decision-theoretic frame. Transfer evidence is strong: canonical, independently named across economics, political science, and evolutionary signaling literatures.'
similarity_to_nearest_existing_prime:
  slug: signaling
  similarity: 0.62
structural_framed:
  label: structural
  aggregate: 0.42
  criteria: {vocab_travels: 0.65, evaluative_weight: 0.35, institutional_origin: 0.35, human_practice_bound: 0.35, import_vs_recognize: 0.45}
  rationale: 'Reads structural-to-mixed. The core claim — a costless, non-binding message whose credibility is contingent on interest-alignment, with a continuum from fully-revealing to babbling equilibria as interests diverge — is recognized rather than imported and travels into diplomacy, advice/persuasion, organizational communication, and aligned-interest animal signaling without carrying game-theoretic machinery. The frame residue is moderate: "message," "sender/receiver," "equilibrium," and "interests" import a game-theoretic cast (keeping institutional_origin and import_vs_recognize off the floor), but the underlying structure — zero-cost communication that informs exactly to the degree that incentives align — is substrate-neutral. Somewhat more framed than a pure structural prime; comparable to its sibling `signaling`.'
phase_b_passes_completed: []
---
# Cheap Talk

## Core Idea

Cheap talk is costless, non-binding communication whose credibility rests *not* on the cost of the message but on the *alignment of interests* between sender and receiver. It is the exact structural complement of costly `signaling` (Spence): the two share the same information-transmission problem — a sender who knows something the receiver does not, and a receiver whose action depends on what the sender knows — but they occupy opposite cost regimes. Costly signaling makes a message credible by making it *expensive*, so that only senders of a given type can afford to send it (credibility by separation: who-can-afford-it). Cheap talk removes the cost entirely: the message is free, unverifiable, and binds the sender to nothing. Its credibility therefore cannot come from cost, and comes instead from incentives — from *how much the sender and receiver want the same thing*.

The load-bearing anatomy is a continuum indexed by interest-alignment. When preferences are sufficiently aligned, even free, unverifiable words transmit real information and shift the receiver's action toward what the sender knows: there is nothing to gain from lying, so "just words" become informative. As interests diverge, the sender's incentive to misrepresent grows, the receiver rationally discounts, and information transmission degrades — until, under sufficient conflict, no message can be believed and communication collapses into a *babbling equilibrium* in which words carry no information at all. Cheap talk is thus a single family of equilibria running from fully-revealing to babbling, with the position on that spectrum set by the alignment of incentives rather than by any property of the message itself. The distinctive four-part signature: (1) message cost ≈ 0; (2) no commitment or binding; (3) credibility contingent on incentive alignment — the more aligned, the more information transmits; (4) a continuum of equilibria from fully-revealing to babbling as interests diverge.

Read structurally, the same shape appears wherever an agent can emit a free, unverifiable message another may act on, and the credibility of that message tracks shared interest rather than message cost. In *diplomacy*, non-binding statements inform to the degree that the parties' interests overlap and decay to noise when they conflict. In *advice and persuasion*, an adviser's free counsel is trusted exactly insofar as the adviser's stake aligns with the advisee's. In *organizational communication*, unverifiable reports up and across a hierarchy inform in proportion to incentive-compatibility between speaker and listener. In *coordination*, a costless focal announcement can move everyone's expectations when interests are common (nobody gains by misdirecting). In *evolutionary biology*, cheap (low-cost) signals remain honest among kin or allies whose interests align, and turn unreliable where they conflict. Across these, the shared abstract structure is costless non-binding communication whose informativeness is a function of interest-alignment — the costless pole of the communication-game family whose costly pole is `signaling`.

## Notes

**Provenance.** Produced by operator 14 (lattice / symmetry completion) as the costless pole of the communication-game family, completing the lattice against the corpus's `signaling` (the costly pole; Spence 1973). Same information-transmission problem, opposite cost regime: costly signaling earns credibility from message cost (separating by who-can-afford-it), cheap talk earns it from interest-alignment. Surfaced 2026-07-04. Canonical construct: Crawford & Sobel 1982 ("Strategic Information Transmission", *Econometrica*) and Farrell & Rabin 1996 ("Cheap Talk", *JEP*). Claimed siblings: non-binding diplomatic statements, advice/persuasion, unverifiable organizational communication, costless focal announcements for coordination, and low-cost honest animal signals among aligned interests. Verified absent from the corpus. Manifest: MODERATE-STRONG hold.

**For owner evaluation (keep/cut).** The case FOR: cheap talk is a *canonical, named construct* (not a proposer coinage), verified absent, and it *completes the communication-game lattice* — the corpus carries the costly pole (`signaling`) but not the costless pole. Its credibility mechanism — alignment-based rather than cost-based — is genuinely distinct and cross-domain (diplomacy, advice, organizational communication, coordination, aligned-interest animal signals). The RISKS Kurt should weigh: (1) **foldability into `signaling`** — the discriminating claim is the *opposite cost regime and a different source of credibility*: signaling separates by cost, cheap talk informs by interest-alignment, and neither reduces to the other; recommend curating them as a two-pole {costly, costless} family rather than merging. (2) **overlap with `coordination` / `common_knowledge`** — cheap talk is a *mechanism* by which costless messages can (under alignment) shift expectations and support coordination, not coordination itself; it should attach by edge, not merger. (3) **overlap with `screening`** — screening is the receiver-side elicitation counterpart to costly signaling and is a different node; screen for confusion. Sharp keep/cut question: *is "costless communication whose credibility comes from interest-alignment" a distinct prime, or a mode of `signaling`?* — the proposer's answer is that opposite cost regime plus a distinct credibility source (alignment, not cost) makes it the genuine costless-pole complement, best kept as a lattice sibling.

**At incorporation.** Re-run similarity against `signaling` (costly-pole sibling), `screening`, `coordination`, `common_knowledge`, and any communication primes to confirm no collapse. If kept: draw a sibling / lattice edge to `signaling` establishing the two-pole {costly, costless} communication-game family, and add missing-edge notes flagging the `coordination` (costless focal announcement as a coordination mechanism) and `screening` (receiver-side counterpart) relationships explicitly. Write a v1 draft and sync the one_liner across v1 and v2 per CLAUDE.md before merge.
