Documentation

Linglib.Studies.NadathurLauer2020

[NL20]: Causal Necessity, Causal Sufficiency, and the Implications of Causative Verbs #

[NL20] [Pea09]

Nadathur & Lauer 2020. Glossa 5(1): 49.

Headline claim #

Periphrastic make and cause differ truth-conditionally:

The two notions are mathematically distinct over a structural-equation framework: there exist scenarios where one holds but the other doesn't, producing minimal-pair contrasts in felicity.

This file formalizes N&L's three illustrative scenarios (§3.6.1-§3.6.3) plus the volitional-action constraint (§4.1, Def 43) that distinguishes make from sister periphrastics like let.

Project-canonical definitions #

The substrate's Necessity.causeSem (in Semantics/Causation/) implements [Nad23b] Definition 10b rather than this paper's literal Def 24. The paper itself anticipates this in fn 18: "the semantics of necessity causatives may well be better explicated in terms of one of the definitions of actual cause, rather than the version of causal necessity defined here." Def 10b IS an actual-cause formulation. The deviation is principled.

Sufficiency.makeSem is the sufficiency clause (b) of N&L's Def 23; the non-inevitability precondition (clause a) is not yet represented in the substrate (it would be falsified by the eager-default development — see the substrate TODO in SEM/Counterfactual.lean).

Scenarios #

Excluded #

Preemption (Suzy/Billy) is not formalized here — N&L footnote 8 explicitly says "we will not discuss the specifics of pre-emption in this paper" — and is not formalized in Studies/Lewis1973.lean either: that file's Overdetermination namespace is symmetric overdetermination (which Lewis's fn. 12 sets aside), not late preemption. See ProductionDependence.lean's discussion for the cross-paper consequence.

Vertices for the fire dynamics (Fig 2): P=power restored, D=drought, G=grass inflammable, L=line down, F=fire.

  • P : V
  • D : V
  • G : V
  • L : V
  • F : V
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      Causal graph: G←{D}; F←{G,P,L}; P,D,L exogenous.

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        Fire dynamics: G := D (inflammability tracks drought); F := G ∧ P ∧ L (fire ignites only when grass inflammable, power on, line touching).

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          noncomputable def NadathurLauer2020.Fire.s_b :
          Causation.Valuation fun (x : V) => Bool

          Background s_b: drought conditions and inflammable grass observed, line condition unknown. (Per N&L p. 19, footnote 21: realistic epistemic ignorance about whether the line was already down.)

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            noncomputable def NadathurLauer2020.Fire.s_b1 :
            Causation.Valuation fun (x : V) => Bool

            Extended background s_b1: the line is also known to be down.

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              (31a) #Restoring power made the field catch fire. Make-side: P=true is NOT sufficient for F=true relative to s_b. With L undetermined, the fire mechanism GPL stays unsettled (Def 23's clause (b) fails).

              (31b, with extended background s_b1 where L is also known) Restoring power caused the field to catch fire. Both make and cause hold. With s_b1 fixing D=G=L=1, P=true is both sufficient and necessary for F=true.

              Vertices for the bus dynamics (Fig 3): Vis=Ava visiting, Tr=training, Rn=rain forecast, Bk=bike gone, Bs=Lia takes the bus.

              • Vis : V
              • Tr : V
              • Rn : V
              • Bk : V
              • Bs : V
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                  Causal graph: Bk←{Vis,Tr}; Bs←{Rn,Bk}; Vis,Tr,Rn exogenous.

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                    Bus dynamics: Bk := Vis ∧ Tr (bike taken when Ava visits AND trains); Bs := Rn ∨ Bk (bus taken when rain OR bike gone). The OR for Bs matches Fig 3's f_B table on p. 20: B=1 iff R=1 or G=1. This creates the "sufficient but unnecessary" structure for T: T=1 forces Bs=1 (sufficient via Bk), but Rn=1 alone also forces Bs=1 (so T not necessary).

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                      noncomputable def NadathurLauer2020.Bus.s_b :
                      Causation.Valuation fun (x : V) => Bool

                      Background s_b: Ava visiting, rain forecast. Training status Tr is the purported cause of bus-taking (via bike taken).

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                        (33a) Ava's training made Lia take the bus to work. Make-side: T=true is sufficient for B=true relative to s_b: under the strict dynamics Bs stays unsettled in the background (Bk waits on Tr), so Def 23's non-inevitability clause (a) holds, and Tr:=1 forces Bk:=1 forces Bs:=1 for clause (b).

                        (33b) #Ava's training caused Lia to take the bus. Cause-side: fails Def 10b necessity via the no-alternative clause, exactly N&L's route: the exogenous settlement s_b[Tr ↦ 0] still entails Bs = 1 (rain alone suffices via the OR mechanism) without entailing Tr = 1.

                        Per-vertex temporal index and the temporal-location constraint ([NL20] Def 28). Local to this study file — promote to substrate (Core/Causal/SEM/Temporal.lean) if a second consumer emerges.

                        Vertices: Q=earthquake (time 1), S=storms (time 2), L=tower collapse (time 3).

                        • Q : V
                        • S : V
                        • L : V
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                              Lighthouse dynamics: L := Q ∧ S (collapse requires both earthquake-induced foundation damage AND extreme storms).

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                                def NadathurLauer2020.Lighthouse.validBackgroundFor (idx : V) (t : ) (s : Causation.Valuation fun (x : V) => Bool) :

                                Temporal location constraint ([NL20] Def 28): a background situation s is valid for a causative claim with evaluation time t iff every vertex s fixes has time ≤ t.

                                Default evaluation time is the cause's time.

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                                  (35d) The storms made the tower collapse. Felicitous: with background fixing Q=true (the earlier necessary cause), S=true suffices for L=true.

                                  (35c) #The earthquake made the tower collapse. Infelicitous via Def 28 temporal-location constraint: the only background under which Q=true would be sufficient for L=true is one fixing S=true, but S happens at time 2 > 1 = time of Q. So no temporally-valid background supports the make-claim.

                                  Concretely: for the make-claim to hold per Def 23(b), the strict development of s + (Q := true) must fix L = 1, which requires S to be fixed in s. But lighthouseTimes .S = 2 > 1, so any such s violates validBackgroundFor lighthouseTimes 1 — S stays u-valued and L = Q ∧ S stays unsettled.

                                  N&L's Def 43 distinguishes make from sister periphrastics like let: when the effect is a volitional action with intention vertex W_E, the background must not fix W_E in a way that makes the cause determinative regardless of the agent's will.

                                  Pairs an effect vertex with its associated intention vertex (W_E). none means the effect is not volitional.

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                                    def NadathurLauer2020.Volitional.volitionalActionConstraint {V : Type u_1} [Fintype V] [DecidableEq V] (M : Causation.BoolSEM V) [M.graph.IsDAG] [Causation.SEM.IsDeterministic M] (intentions : IntentionMap V) (bg : Causation.Valuation fun (x : V) => Bool) (cause effect : V) :

                                    Constraint on volitional action ([NL20] Def 43): in the evaluation of a make-causative with cause C and effect E, no intention vertex W_E paired with E may be such that BOTH (i) W_E := false is sufficient for E := false relative to bg + (C := true) AND (ii) W_E is determined by bg \ (C := true).

                                    For deterministic SEMs makeSem ... wE false eff false is the sufficiency check; (bg.remove cause).get wE ≠ none is the determined-ness check.

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                                      Vertices: WD = children's desire to dance, G = Gurung's permission, D = children dance.

                                      • WD : V
                                      • G : V
                                      • D : V
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                                            Permission dynamics (Fig 5): D := W_D ∧ G. Both desire AND permission needed for dancing.

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                                              noncomputable def NadathurLauer2020.Permission.bg :
                                              Causation.Valuation fun (x : V) => Bool

                                              Background: children eager to dance (W_D := true). Cause is G (Gurung's permission); effect is D (dancing).

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                                                Bare sufficiency holds: G:=true is sufficient for D=true given W_D=true.

                                                (40a) ??Gurung made the children dance. Volitional-action constraint VIOLATED: with W_D fixed in bg, W_D := false is sufficient for D := false (W_D ∧ G with W_D=false gives false), and W_D is determined by bg \ {G} (W_D was in bg, removing G doesn't unfix it). Per Def 43, this rules out felicitous use of make.

                                                (40a) Combined predicate: bare make-sufficiency AND volitional constraint must BOTH hold for make to be felicitous. Permission scenario gives the former but fails the latter — N&L's headline §4.1 prediction.

                                                Command scenario: same vertices as Permission, different mechanism. Bg may or may not fix W_D — N&L's (41)/(42) show make felicitous in either case, so command-style mechanism makes W_D irrelevant once G fires.

                                                • WD : V
                                                • G : V
                                                • D : V
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                                                      Command dynamics (Fig 6): D := W_D ∨ G. Either authority alone OR independent desire suffices for dancing.

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                                                        noncomputable def NadathurLauer2020.Command.bgEager :
                                                        Causation.Valuation fun (x : V) => Bool

                                                        (41) context: the children are independently eager (W_D = 1).

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                                                          noncomputable def NadathurLauer2020.Command.bgReluctant :
                                                          Causation.Valuation fun (x : V) => Bool

                                                          (42) context: the children are reluctant (W_D = 0).

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                                                            (41) Bare sufficiency in the eager context: with W_D = 1 fixed, D = W_D ∨ G stays unsettled while G is (Def 23a holds under the strict dynamics), and G := 1 settles it. N&L's (41)/(42) contexts differ only in the background setting of W_D; make is felicitous in both.

                                                            (42) Bare sufficiency in the reluctant context (W_D = 0).

                                                            (42a) Gurung made the children dance (reluctant context). Volitional-action constraint SATISFIED: W_D := false is NOT sufficient for D := false (D = W_D ∨ G with G = 1 settles true regardless), so Def 43's bad condition fails on its first conjunct.

                                                            (42a) Combined: the reluctant command scenario gives BOTH bare sufficiency AND volitional-constraint satisfaction → make-felicitous.

                                                            Persuasion scenario: G manipulates W_D, then W_D drives D. Distinct mechanism: G acts via the agent's desire, not in parallel.

                                                            • WD : V
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                                                            • D : V
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                                                                  Persuasion dynamics (Fig 7): W_D := G (Gurung's action shapes desires); D := W_D (children dance iff they want to).

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                                                                    (44a) Gurung made the children dance (by playing their favourite song). Volitional-action constraint SATISFIED: although W_D := false is sufficient for D := false (D = W_D), W_D is NOT determined by the background (empty bg leaves W_D undetermined). Second conjunct of Def 43's bad condition fails.

                                                                    N&L §4.2 argues that the necessity inference of make is a pragmatic enrichment, not entailed content. Their argument runs through implicature tests: - Cancellability (49): "Gurung made the children dance, but they might have danced anyway" — felicitous, cancels the necessity reading without contradiction. - Reinforceability (50): "The data made me do it. I would never have done it otherwise." — felicitous, reinforces the necessity reading without redundancy. - Soccer camp (16): a fully felicitous use of make in an explicitly necessity-denying context.

                                                                    Structurally, these all follow from N&L's headline result that
                                                                    *make* asserts sufficiency only — necessity is a separable layer.
                                                                    The Bus and Fire scenarios already witness this:
                                                                    - Bus: `make` holds while necessity (`cause`) fails (sufficient ≠ necessary)
                                                                    - Fire (with known line): `make` and `cause` hold without redundancy
                                                                      (the two assertions are independently informative)
                                                                    
                                                                    These scenarios are the structural counterpart of the implicature
                                                                    tests; the prose tests follow from them. 
                                                                    

                                                                    Cancellability witness (cf. (49)): the bus scenario shows that make can hold while cause (necessity) fails. So if make did entail necessity, this scenario would be contradictory; since it's not, the necessity inference must be cancellable.

                                                                    Reinforceability witness (cf. (50)): the fire scenario with known-line background gives both make and (predictably) cause felicity. Asserting "the data made me do it; I'd never have done it otherwise" reinforces necessity onto a sufficiency-asserting make-claim — felicitous because the two assertions are independent.

                                                                    N&L's central observation against entailment-based taxonomy: periphrastic causatives share [Kar71]'s sufficient-only entailment cell while differing in causal mechanism (sufficiency for make vs necessity for cause). The comparison is N&L's, so it lives here; necessity_cancellable above is its kernel-checked witness.

                                                                    Derive the KarttunenClass cell from an Implicative polarity (two-way cell: complement entailment under both polarities).

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                                                                      Map modern Causative to the Karttunen cell that matches the builder's entailment pattern (Karttunen's original criterion).

                                                                      All positive causative builders (make, force, enable, cause) share the same Karttunen cell: sufficient-only. This is because:

                                                                      • Affirmative "V-ed X to VP" → VP (all require the effect occurred)
                                                                      • Negation "didn't V X to VP" ↛ ¬VP (effect might occur from other causes)

                                                                      [NL20]'s insight: these verbs differ in causal MECHANISM (sufficiency vs necessity) despite sharing the same ENTAILMENT PATTERN. See cause_make_same_cell_different_mechanism.

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                                                                        All positive causative builders map to KarttunenClass.force (Karttunen's sufficient-only cell).

                                                                        cause and make have the same Karttunen entailment cell (sufficient-only) despite having different causal mechanisms. This is the central insight of [NL20]: same entailment pattern ≠ same truth conditions. The difference is kernel-checked at NadathurLauer2020.necessity_cancellable (the Bus scenario: makeSem holds while causeSem fails).