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Linglib.Phenomena.Persuasion.Studies.CumminsFranke2021

@cite{cummins-franke-2021}: Argumentative Strength of Numerical Quantity #

@cite{cummins-franke-2021}

Formalizes the conference registration scenario (C&F pp. 7–8) demonstrating that semantic and pragmatic argumentative strength can reverse the ordering of "more than M" expressions, and the REF 2014 case study on strategic use of "top M" claims (C&F §5, pp. 10–14).

Key Results #

  1. Semantic measure: "more than 110" > "more than 100" for goal "success" (because "more than 110" concentrates probability mass in goal-worlds)
  2. Pragmatic reversal: with 90% enrichment, the ordering flips — "more than 100" becomes pragmatically stronger (C&F Eq. 25)
  3. REF case study: universities use round "top M" claims and prefer the ranking measure on which they score better (C&F §5)

See also MacuchSilvaEtAl2024.lean for the experimental follow-up on strategic quantifier choice in exam scenarios.

Methodology #

All ordinal comparisons use Bayes factor ratios (exact ℚ arithmetic), which are equivalent to comparing argStr values since log is monotone. This avoids dependence on log approximations.

"More than M" is equivalent to lower-bound meaning at M+1.

moreThan(M)(n) = true ↔ n > M ↔ n ≥ M+1 = lowerBound(M+1)(n)

These theorems ground the conference scenario's semantics in the canonical moreThanMeaning from Numeral.Semantics. The conference scenario (§2) uses probability counts directly for tractability, but the underlying denotation is the same.

P("more than 100" | G) = 1: all goal-worlds (value > 120) satisfy value > 100.

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    P("more than 100" | ¬G) = 20/120 = 1/6: among ¬G worlds (value in [0, 120]), values > 100 span (100, 120], measure 20 out of 120. (C&F p. 7)

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      P("more than 110" | G) = 1: all goal-worlds satisfy value > 110.

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        P("more than 110" | ¬G) = 10/120 = 1/12: among ¬G worlds, values > 110 span (110, 120], measure 10 out of 120. (C&F p. 7)

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          "More than 110" has a higher Bayes factor than "more than 100" for the conference goal.

          BF("mt110") = 1/(1/12) = 12 > BF("mt100") = 1/(1/6) = 6.

          This is C&F's key semantic result: the more precise (higher M) expression has higher argStr because it has lower P(u|¬G). (C&F p. 7)

          P_A("more than 100" | G): 90% × P(value ∈ (100,150] | value ∈ (120,200]) + 10% × P(value > 100 | value ∈ (120,200]) = 90% × 30/80 + 10% × 1 = 27/80 + 8/80 = 35/80. (C&F p. 8)

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            P_A("more than 100" | ¬G) = 1/6: Both enriched and literal paths give the same probability, since (100,150] ∩ [0,120] = (100,120] and literal >100 in [0,120] is also (100,120]. Total: 90% × 1/6 + 10% × 1/6 = 1/6. (C&F p. 8)

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              P_A("more than 110" | G) = 1/10: 90% × P(value ∈ (110,120] | value ∈ (120,200]) + 10% × P(value > 110 | value ∈ (120,200]) = 90% × 0 + 10% × 1 = 1/10. The enriched range (110,120] doesn't intersect the goal range (120,200]. (C&F p. 8)

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                P_A("more than 110" | ¬G) = 1/12: Both paths give P(value > 110 | value ∈ [0,120]) = 10/120 = 1/12. Total: 90% × 1/12 + 10% × 1/12 = 1/12. (C&F p. 8)

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                  PRAGMATIC REVERSAL: "more than 100" becomes pragmatically stronger.

                  BF_prag("mt100") = (35/80)/(1/6) = 21/8 = 2.625 BF_prag("mt110") = (1/10)/(1/12) = 6/5 = 1.2

                  This is C&F's central result (p. 8). Semantically mt110 > mt100, but pragmatically mt100 > mt110. The enrichment of "more than 110" to "not more than 120" makes it nearly unassertable in goal-worlds (P_A = 1/10), while "more than 100" enriched to "not more than 150" retains substantial assertability (P_A = 35/80).

                  theorem Phenomena.Persuasion.Studies.CumminsFranke2021.wider_enrichment_weakens_argStr (pG pNotG_narrow pNotG_wide : ) (hG : 0 < pG) (hNarrow : 0 < pNotG_narrow) (hWide : 0 < pNotG_wide) (hWider : pNotG_narrow < pNotG_wide) :

                  Structural theorem: when P_a(u|¬G) increases (through wider enrichment), the Bayes factor decreases and thus argStr decreases. This is the mechanism behind the pragmatic reversal.

                  Claim type: absolute rank ("top M") or percentile ("top M per cent")

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                      A "top M" datum from C&F §5, examples 29–38 (p. 12)

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                          C&F examples 29–38: UK universities' "top M" claims from REF 2014 reports.

                          All claimed M values are round numbers (multiples of 5 or 10). Data verified against C&F p. 12. REF 2014 had 154 multi-subject institutions.

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                            H1 verification: all claimed M values are round (multiples of 5)

                            H1 verification: absolute claims are truthful (actual rank ≤ claimed M)

                            H1 verification: percentile claims are truthful. REF 2014 had 154 institutions; top 10% = rank ≤ 16, top 25% = rank ≤ 39.

                            H2 data: ranking measure preference (C&F p. 13).

                            Of 39 institutions with data, 19 ranked higher on GPA and 19 on power (Durham 20th on both). Institutions systematically prefer the measure on which they rank better.

                            • groupSize :
                            • citedPreferred :
                            • citedNonPreferred :
                            • citedNeither :
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                                GPA-preferred group: 9 cite GPA, 0 cite power, 10 cite neither. (p < 0.01, sign test; C&F p. 13)

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                                  Power-preferred group: 11 cite power, 2 cite GPA, 6 cite neither. (p < 0.05, sign test; C&F p. 13)

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                                    H2: in each group, more institutions cite their preferred measure than the non-preferred one.