---
title: "Must φ is felicitous only if φ is not known — paper by Goodhue (2017)"
description: "Goodhue constructs minimal pairs where both speakers perceive exactly the same things, but only one of them can naturally say \"It must be… 5 references."
authors: ["Daniel Goodhue"]
year: 2017
venue: "Semantics and Pragmatics"
source: "https://semprag.org/index.php/sp/article/view/sp.10.14"
doi: "10.3765/sp.10.14"
licence: "CC BY 3.0"
licence_url: "https://creativecommons.org/licenses/by/3.0/"
summary_licence: "Elamur Cosmic License"
canonical: "https://research.elamur.ai/free/en/papers/goodhue-2017-must-is-felicitous-only-if/"
---
[Elamur Research](https://md.research.elamur.ai/free/en/) · [this page in HTML](https://research.elamur.ai/free/en/papers/goodhue-2017-must-is-felicitous-only-if/)

[home](https://md.research.elamur.ai/free/en/) / [papers](https://md.research.elamur.ai/free/en/papers/) / [2017](https://md.research.elamur.ai/free/en/papers/2017/page/4/) / Must φ is felicitous only if φ is not known

# Must φ is felicitous only if φ is not known

**Authors:** [Daniel Goodhue](https://md.research.elamur.ai/free/en/authors/daniel-goodhue/) · **Year:** 2017 · **Venue:** [Semantics and Pragmatics](https://md.research.elamur.ai/free/en/venues/semantics-and-pragmatics/) ([Semantics and Pragmatics 2017](https://md.research.elamur.ai/free/en/venues/semantics-and-pragmatics/2017/)) · **Publisher:** [Linguistic Society of America](https://md.research.elamur.ai/free/en/publishers/linguistic-society-of-america/) · **Licence:** [CC BY 3.0](https://creativecommons.org/licenses/by/3.0/)

**Links:** [Publisher's page](https://doi.org/10.3765/sp.10.14) · [PDF](https://semprag.org/index.php/sp/article/download/sp.10.14/pdf) · [DOI 10.3765/sp.10.14](https://doi.org/10.3765/sp.10.14) · [OpenAlex](https://openalex.org/W2777343907)

**Citations:** 14 citations (OpenAlex, 2026-10-14)

## Summary
The paper asks what licenses English epistemic *must*. One influential view (von Fintel & Gillies 2010) says *must φ* is felicitous only when the evidence for φ is indirect. Goodhue constructs minimal pairs where both speakers perceive exactly the same things, but only one of them can naturally say "It must be raining." He argues that the indirectness view can handle these pairs only by stipulating that what counts as "direct" shifts with context. A knowledge-based condition explains them in a principled way: *must φ* is fine only if the speaker does not know φ, as Giannakidou & Mari (2016) proposed. Theories of knowledge such as Lewis 1996 then account for why one speaker knows and the other does not. Combined with Kratzer's ordering-source semantics, this supports a *weak* reading of *must*, where stereotypical assumptions are needed to reach φ. The author also sketches how the condition could be derived as a conversational implicature. He shows that *must* in deductive conclusions puzzles every account, and suggests treating it as a separate modal flavor.

## Key points
- The two rival felicity conditions are:
  - **indirectness**: no directly known proposition entails φ (von Fintel & Gillies 2010; Matthewson 2015; Lassiter 2016; Mandelkern 2016);
  - **non-knowledge**: the known propositions ∩Epi do not entail φ (Giannakidou & Mari 2016).
- The semantic backbone is Kratzer 1991:
  - a modal base Epi is ordered by a stereotypical source Norm;
  - *must* quantifies over the resulting Best worlds;
  - so *must φ* can be true while φ is false, which captures Karttunen's 1972 weakness intuition.
- The paper argues that G&M's piano examples do not refute indirectness, because trustworthy reports count as direct evidence for von Fintel & Gillies. New identical-perception pairs are offered instead.
- The new evidence for the epistemic account also favors a weak, non-entailing semantics for *must* (in line with Karttunen, Kratzer, Lassiter and G&M).
- Deductive conclusions are a puzzle for both accounts. Cross-linguistic hints of a distinct deductive modal:
  - Spanish *debe de* vs. *tiene que*;
  - Portuguese *deve* vs. *tem de* (Marques 2020).

## Interesting ideas
- Hold the perceptual evidence fixed and vary only the background beliefs (e.g. a scheduled fake-rain shoot) to isolate whether a cue depends on evidence type or on knowledge state; this controlled minimal-pair design generalizes to any pragmatic diagnostic.
- Treat *must φ* as signalling that the speaker does not fully know φ but reached it via default assumptions, not as a claim that φ holds.
- Derive the "not known" signal as a quantity-style implicature: had the speaker known φ, the bare assertion would have been the expected choice.
- Distinguish epistemic *must* from deductive *must* (conclusion of explicit premises), using cues like a preceding *therefore/then* or enumerated premises, mirroring the Spanish/Portuguese lexical split.
- Model *must* with a modal base plus an ordering source (known facts vs. normal-course assumptions), keeping the two sets explicit.

## For Mova

How these ideas could serve Mova, our small open language model — its files, stages and tests:

- **I1** (learn): Build negative-control test pairs where only the speaker's background knowledge differs, and check that the modal/certainty analysis flips accordingly.
- **I2** (world): Store *must φ* in the text world as a speaker-attributed, defeasible belief tagged "inferred via assumptions" rather than as an asserted fact, so later contradictions do not break consistency.
- **I3** (frames): In crate prag, add an implicature rule that *must/probably* triggers "speaker lacks knowledge of φ", which is cancellable and can be explained by pointing to the stronger unused alternative.
- **I4** (answer): In logic or word-problem readers, treat "therefore it must be X" after premises as a certain derived conclusion rather than a hedge, avoiding false uncertainty in answers.
- **I5** (world): Represent known facts and stereotypical defaults as separate layers, so every modal inference can be explained as "facts + these defaults ⇒ φ".

*Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.*

## Institutions

- [McGill University](https://md.research.elamur.ai/free/en/universities/mcgill-university/) — University, Montreal, Canada · 51 works · 10,476 citations

📚 Shelves (5): [🖥️ Computer Science](https://md.research.elamur.ai/free/en/shelves/computer-science/) · 9,086 works · [🤖 Artificial Intelligence](https://md.research.elamur.ai/free/en/shelves/computer-science/artificial-intelligence/) · 8,889 works · [🎭 Arts and Humanities](https://md.research.elamur.ai/free/en/shelves/arts-and-humanities/) · 9,296 works · [🗣️ Language and Linguistics](https://md.research.elamur.ai/free/en/shelves/arts-and-humanities/language-and-linguistics/) · 9,206 works · [🤔 Philosophy](https://md.research.elamur.ai/free/en/shelves/arts-and-humanities/philosophy/) · 211 works

🧭 Topics (1): [English](https://md.research.elamur.ai/free/en/topics/english/) · 1,373 works

## Cite

Cite as: Daniel Goodhue. 2017. Must φ is felicitous only if φ is not known. Semantics and Pragmatics.

The paper itself, not this page. BibTeX from the library's record of the work.

```bibtex
@article{goodhue2017must,
  title = {{Must φ is felicitous only if φ is not known}},
  author = {Daniel Goodhue},
  journal = {Semantics and Pragmatics},
  year = {2017},
  doi = {10.3765/sp.10.14},
  url = {https://doi.org/10.3765/sp.10.14}
}
```

- [← previous Dependency Tree Transformation with Tree Transducers](https://md.research.elamur.ai/free/en/papers/hennig-2017-dependency-tree-transformation-tree-transducers/)
- [next → Projection-based Coreference Resolution Using Deep Syntax](https://md.research.elamur.ai/free/en/papers/novak-2017-projection-based-coreference-resolution-deep/)
- [↑ back to papers of 2017](https://md.research.elamur.ai/free/en/papers/2017/page/4/)

## References

5 references, 0 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

1. Blome-Tillmann, Michael. 2009. Knowledge and presuppositions. Mind 118 (470). 241–294. https://doi.org/10.1093/mind/fzp032. [↗](https://doi.org/10.1093/mind/fzp032)
2. Fagin, Ronald, Joseph Y Halpern, Yoram Moses & Moshe Vardi. 1995. Reasoning about knowledge. Cambridge, MA: MIT press. [↗](https://doi.org/10.7551/mitpress/5803.001.0001)
3. Fagin, Ronald & Joseph Y. Halpern. 1987. Belief, awareness, and limited reasoning. Artificial Intelligence 34(1). 39–76. https://doi.org/10.1016/0004-3702(87)90003-8. [↗](https://doi.org/10.1016/0004-3702(87)90003-8)
4. Faller, Martina T. 2002. Semantics and pragmatics of evidentials in Cuzco Quechua. Palo Alto, CA: Stanford University dissertation. [find](https://scholar.google.com/scholar?q=Faller%2C+Martina+T%2E+2002%2E+Semantics+and+pragmatics+of+evidentials+in+Cuzco+Quechua%2E+Palo+Alto%2C+CA%3A+Stanford+University+dissertation%2E)
5. Faller, Martina T. 2012. Evidential scalar implicatures. Linguistics and Philosophy 35(4). 285–312. https://doi.org/10.1007/s10988-012-9119-8. [↗](https://doi.org/10.1007/s10988-012-9119-8)

*Updated 24 October 2026*