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Linglib.Comparisons.FreeChoice

Free Choice: Theory Comparison #

@cite{aloni-2022} @cite{alsop-2024} @cite{bar-lev-fox-2020} @cite{champollion-alsop-grosu-2019} @cite{elliott-2025} @cite{fox-2007}

Comparing how different theories derive free choice inferences.

The Puzzle #

"You may have coffee or tea" pragmatically implies: "You may have coffee AND you may have tea"

Semantically: ◇(A ∨ B) ↔ ◇A ∨ ◇B (standard modal logic) Pragmatically: ◇(A ∨ B) → ◇A ∧ ◇B (free choice!)

Theories Compared #

  1. @cite{fox-2007}: Double exhaustification (Exh²) with Innocent Exclusion
  2. @cite{bar-lev-fox-2020}: Innocent Inclusion (II) + Innocent Exclusion (IE)
  3. @cite{champollion-alsop-grosu-2019}: RSA with semantic uncertainty (disjunction)
  4. @cite{alsop-2024}: RSA with Global Intentions (universal any)
  5. @cite{aloni-2022}: BSML - Bilateral State-based Modal Logic (team semantics)
  6. @cite{elliott-sudo-2025}: BUS - Bilateral Update Semantics (dynamic)

The Core Puzzle #

Standard modal logic gives us: ◇(A ∨ B) ↔ ◇A ∨ ◇B

But pragmatically, we infer: ◇(A ∨ B) → ◇A ∧ ◇B

This is not a semantic entailment. The challenge is to derive it pragmatically.

  1. Free Choice Inference (FCI): ◇(A ∨ B) → ◇A ∧ ◇B

    • "You may have coffee or tea" → "You may have coffee" AND "You may have tea"
  2. Exclusivity Inference (EI): ◇(A ∨ B) → ¬◇(A ∧ B)

    • "You may have coffee or tea" → "You may not have both"

FCI is robust; EI is cancelable. Any theory must explain this asymmetry.

@cite{fox-2007}: Free Choice via Recursive Exhaustification #

The original grammatical account: recursive application of exh (the covert exhaustivity operator) derives FC without Innocent Inclusion.

See Exhaustivity/Fox2007.lean for the computable algorithm and full derivation.

Neo-Gricean Account: Innocent Inclusion #

@cite{bar-lev-fox-2020} extend @cite{fox-2007}'s Innocent Exclusion with Innocent Inclusion.

The Mechanism #

Step 1: Innocent Exclusion (IE)

Step 2: Innocent Inclusion (II)

Step 3: Combined Exhaustification Exh^{IE+II}(φ) = φ ∧ ∀q ∈ IE[¬q] ∧ ∀r ∈ II[r]

Why It Works for Free Choice #

The key is closure under conjunction:

Alternative SetClosed under ∧?Result
{a∨b, a, b, a∧b}YESExclusive-or
{◇(a∨b), ◇a, ◇b, ◇(a∧b)}NOFree choice

For FC alternatives:

RSA Account: Semantic Uncertainty #

@cite{champollion-alsop-grosu-2019} use RSA with multiple interpretation functions (following @cite{bergen-levy-goodman-2016}'s lexical uncertainty).

The Mechanism #

Two Interpretation Functions:

For "You may A":

The Derivation:

  1. Speaker wants to convey "Only One" (you may choose either)
  2. If speaker says "You may A", hearer might use I₂ → "Only A"
  3. To avoid this, speaker uses "You may A or B"
  4. Hearer reasons: "Speaker avoided A to prevent me thinking Only A"
  5. Hearer concludes: Must be Only One or Any Number → FCI!

Insight #

The semantic uncertainty creates an avoidance pattern:

RSA Account for Universal Any: Global Intentions #

@cite{alsop-2024} extends the RSA approach to universal free choice items like any, using the Global Intentions model from @cite{franke-bergen-2020}.

The Mechanism #

Two Parses (instead of two interpretation functions):

The Derivation:

  1. Speaker wants to convey "you may take any (= each) class"
  2. If speaker uses weak parse, hearer might only infer "some class is OK"
  3. To be informative, speaker intends the strong (Dayal) parse
  4. Hearer reasons: "Speaker chose 'any' with the strong parse"
  5. Hearer concludes: Each class is individually permitted → Exclusiveness!

Key Parallel to Champollion et al. #

AspectDisjunction (@cite{champollion-alsop-grosu-2019})Universal any (2024)
FC inference◇(a∨b) → ◇a ∧ ◇b◇∃x.P(x) → ∀x.◇P(x)
Robust inferenceFCIExclusiveness
Prior-sensitiveEI (not-both)Not-every
AmbiguityInterpretation (I₁/I₂)Parse (Szabolcsi/Dayal)

Semantic Account: BSML (Bilateral State-based Modal Logic) #

@cite{aloni-2022} derives FC semantically using team semantics.

The Mechanism #

Split Disjunction: t ⊨ φ ∨ ψ iff ∃t₁,t₂: t₁ ∪ t₂ = t ∧ t₁ ⊨ φ ∧ t₂ ⊨ ψ

Non-emptiness Enrichment: [φ]⁺ adds NE constraints recursively

FC Derivation:

  1. [◇(α ∨ β)]⁺ = ◇([α]⁺ ∨ [β]⁺) ∧ NE
  2. Split disjunction partitions the team
  3. [α]⁺ and [β]⁺ both include NE, so both parts must be non-empty
  4. Therefore ◇α and ◇β are both supported

Semantic Account: BUS (Bilateral Update Semantics) #

@cite{elliott-sudo-2025} derive FC semantically using dynamic bilateral updates.

The Mechanism #

Modal Disjunction Precondition: s[φ ∨ ψ]⁺ = s[φ ∨ ψ]⁺ if s[φ ∨ ψ]⁺₁ ≠ ∅ AND s[φ ∨ ψ]⁺₂ ≠ ∅, else ∅

FC Derivation:

  1. For ◇(φ ∨ ψ) to be possible, positive update must be non-empty
  2. This requires BOTH disjuncts to contribute possibilities
  3. Therefore ◇φ and ◇ψ are both possible

Key Advantage: Cross-Disjunct Anaphora #

BUS is uniquely designed to handle "bathroom disjunctions":

Elliott & Sudo FC is derived from modal disjunction semantics. The BUS module provides FC derivation via:

Side-by-Side Comparison #

AspectBar-Lev & FoxChampollion et al.AlsopAloniE&S
FrameworkNeo-GriceanRSARSATeam SemDynamic
TypePragmaticPragmaticPragmaticSemanticSemantic
Key mechanismInnocent InclusionSemantic uncertaintyParse ambiguityNE + split ∨Modal ∨ precond
NatureCategoricalProbabilisticProbabilisticCategoricalCategorical
AnaphoraNoNoNoNoYes
Why FC worksNon-closureAvoid I₂Dayal informativeNE forces bothBoth contribute

Comparison result type (extended for all theories)

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      FCI: All theories derive it

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        Dual Prohibition: Negation blocks FC

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          Secondary inference asymmetry

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            Cross-disjunct anaphora

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              All comparisons

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                Pragmatic vs Semantic Derivation #

                A key division among FC theories:

                Pragmatic Approaches (FC as implicature) #

                Semantic Approaches (FC built into meaning) #

                Trade-offs #

                AspectPragmaticSemantic
                FC sourceReasoning about alternativesLexical meaning
                CancelabilityPredicted (pragmatic)Must be stipulated
                GradientRSA: yes; Neo-Gricean: noNo
                Cross-disjunct anaphoraHard to captureBUS: natural
                Dual prohibitionRequires explanationBuilt in

                Approach classification

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                    Different Structural Insights #

                    Bar-Lev & Fox: Closure Under Conjunction #

                    The key structural property is whether the alternative set is closed under ∧.

                    Simple disjunction: ALT = {a∨b, a, b, a∧b}

                    FC disjunction: ALT = {◇(a∨b), ◇a, ◇b, ◇(a∧b)}

                    Aloni: Non-Emptiness + Split Disjunction #

                    The key is that disjunction SPLITS the team: t ⊨ φ ∨ ψ iff ∃t₁,t₂: t₁ ∪ t₂ = t ∧ t₁ ⊨ φ ∧ t₂ ⊨ ψ

                    Combined with pragmatic enrichment adding NE: [φ ∨ ψ]⁺ = ([φ]⁺ ∨ [ψ]⁺) ∧ NE

                    Each part of the partition must be non-empty → both disjuncts possible!

                    Elliott & Sudo: Bilateral + Precondition #

                    Modal disjunction has a PRECONDITION requiring both disjuncts contribute: s[φ ∨ ψ]⁺ = s[φ ∨ ψ]⁺ if s[φ ∨ ψ]⁺₁ ≠ ∅ AND s[φ ∨ ψ]⁺₂ ≠ ∅, else ∅

                    This SEMANTICALLY derives FC: if the disjunction is assertable, both must contribute possibilities.

                    Bar-Lev & Fox: closure under conjunction determines outcome.

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                        Where Theories Make Different Predictions #

                        1. Gradient vs Categorical Judgments #

                        Pragmatic (RSA): FCI is gradient (probability varies with α, priors) Pragmatic (Neo-Gricean): FCI is categorical Semantic: FCI is categorical (semantic entailment)

                        Test: Do speakers show gradient acceptance of FC readings?

                        2. EI Cancelability Asymmetry #

                        Bar-Lev & Fox: Both FCI and EI derived by same mechanism Champollion et al.: FCI from reasoning, EI from priors → asymmetry Semantic: Must explain cancelability differently

                        3. Cross-Disjunct Anaphora #

                        Most theories: Cannot handle "Either there's no bathroom or it's upstairs" Elliott & Sudo: Primary motivation; handles via bilateral + DNE

                        Empirical prediction type

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                                  Predictions for Phenomena Data #

                                  All theories correctly predict the patterns in Phenomena.FreeChoice.Data:

                                  Basic Free Choice (coffeeOrTea) #

                                  Ross's Paradox (postOrBurn) #

                                  Cancellation (explicitCancellation) #

                                  Summary: Free Choice Theory Landscape #

                                  Five Theories, Two Approaches #

                                  Pragmatic (FC as implicature):

                                  Semantic (FC in meaning):

                                  Key Differentiators #

                                  FeatureBest Theory
                                  Gradient judgmentsRSA approaches
                                  EI asymmetryRSA approaches
                                  Formal precisionBar-Lev & Fox
                                  Cross-disjunct anaphoraElliott & Sudo
                                  Static team semanticsAloni

                                  Complementary Insights #

                                  Each theory contributes something unique: