Khoo (2015): Modal Disagreements

This file records the experiment of [Kho15] on disagreements over epistemic modal claims. Participants read a control vignette with a non-modal assertion and a modal vignette in which Smith, having examined evidence consistent with Fat Tony's death, says Fat Tony might be dead while Beth knows him to be alive, and rated on a seven-point scale either whether what the speaker said is false or whether they would respond No, ... (section II; Data/Examples/Khoo2015). The Difference Observation is that the modal claim is rejected readily yet not judged false, a dissociation the control assertion lacks (difference_observation): speakers reject the might-claim without judging it false.

Implementation notes

The cell means and standard deviations of footnote 13 are Data/Experiments/Khoo2015, which the released survey reproduces; "readily" and "not" are read against the scale's midpoint. The paper's account of the observation is not formalized.

References

• [Kho15]

def Khoo2015.mean (s : Sentence) (r : Response) : ℚ

The mean rating of a vignette under a question.

Equations

• Khoo2015.mean s r = (Khoo2015.ratings s r).mean.toRat

theorem Khoo2015.difference_observation : (↑midpoint < mean Sentence.modal Response.rejection ∧ mean Sentence.modal Response.judgedFalse < ↑midpoint) ∧ mean Sentence.control Response.rejection ≤ mean Sentence.control Response.judgedFalse

The Difference Observation: the modal claim is rejected above the scale's midpoint yet judged false below it, while the control assertion is judged false at least as readily as it is rejected.