An important challenge in understanding human communication is the question of what processes drive message construction. Why do speakers construct utterances in the way they do? How do they generate utterances to achieve their intended effects? Recently, speaker commitment emerged as fundamental in answering these questions (Geurts 2019): utterances commit the speaker to the truth of a proposition or to a future course of action (Hamblin 1971; Beyssade and Marandin 2009), but such commitments are only effective if listeners are able to track these commitments and hold speakers accountable to them (e.g., Vullioud et al. 2017; see also Mahr and Csibra 2018, 2020, 2021).

How speakers choose to express their message should impact how committed they are perceived to be – how much others will hold them accountable to what they have expressed and the degree of plausible deniability of their message. Speakers are held accountable for the message they convey and will incur reputational costs if it is found to be unreliable (Boulat and Maillat 2017; Brabanter and Dendale 2008). It is therefore sometimes in their interest if this message is conveyed in such a way that it is plausibly deniable. While the notion of plausible deniability is first a psychological one, which relies on intuitive judgments, several theoretical analyses have now been put forward to account for it (Camp 2018, 2022; Dinges and Zakkou 2023; Mazzarella 2021; Pinker 2007; Pinker et al. 2008). Plausible deniability allows speakers to refute having intended a certain message (typically an implicit one), for instance when confronted by the recipient (Brown and Levinson 1987; Lee and Pinker 2010; Pinker 2007; Pinker et al. 2008). By taking a strategic approach to utterance construction, speakers can manipulate the extent to which the audience can hold them accountable for the meaning they have conveyed (Pinker et al. 2008; Soltys et al. 2014). Illustrating this, Lee and Pinker (2010) found that speakers favoured implicit constructions when they were asked how they would attempt to bribe a policeman. The choice to forego an explicit offer in such a scenario is strategic, as speakers can deny their implicit offer and avoid unpleasant and/or awkward social repercussions. Speakers can thus mitigate the risks of a negative outcome, since ‘cooperative’ recipients can accept implicit offers, while ‘antagonistic’ recipients would not have enough evidence to confront them. Therefore, how committed speakers are perceived to be is importantly related to plausible deniability. On the one hand, deniability might influence how speakers construct their utterances in strategics situations. On the other hand, plausible deniability might be a function of how strongly a speaker is committed.

However, while multiple factors have been found to influence perceived speaker accountability, much less work has focused on the factors that determine plausible deniability beyond how explicitly or implicitly a message is conveyed. One factor research has focused on is speaker’s confidence in expressing a message, which can be marked either linguistically (e.g., ‘I guess’, ‘I’m sure’) or non-verbally through posture, gestures, tone of voice or facial expressions. Speaker confidence has been found to impact both the message’s credibility – by increasing its chances of being accepted by the interlocutor – and the speaker’s accountability – namely the social repercussions if the message is found to be unreliable (Vullioud et al. 2017; Mazzarella et al. 2018). Similarly, claims about the source of one’s information (“I saw it” vs. “Somebody told me”) have been shown to have an impact on the message’s credibility, as well as the speaker’s accountability (Mahr and Csibra 2021).

Here we extend this work, by focusing explicitly on two additional pragmatic factors that might not only influence speaker accountability but also plausible deniability: the level of meaning and its strength. First, speakers can convey messages with different degrees of explicitness, that is, using different levels of meaning: speakers communicate not only the linguistically encoded meaning of their utterances, they can also pragmatically enrich the content of these utterances or implicate propositions in addition to what they explicitly say (Grice 1989). The meaning of the conjunction ‘and’, for instance, can be pragmatically enriched to ‘and then’. An utterance of “they got married and had a child” will then prompt the hearer to believe the two events happened in a certain order. The meaning of an utterance can depart even more from its linguistic form and its explicit content through an implicature, for instance when a child’s request for a snack is met with an implicit denial in the form of “dinner will be ready in 10 minutes”.

Second, speakers can convey messages with different degrees of manifestness – e.g., a pragmatically inferred part of meaning (be it an enrichment or an implicature) may be more or less strongly communicated. Meaning strength is conceived here as the accessibility of what is communicated; it depends both on how manifest the speaker made their intention to communicate a specific content and how important (or inconsequential) the recovery of this content is for the interpretation of the utterance (Wilson and Sperber 2004). Meaning strength depends on the context of the utterance. For instance, “they got married and had a child” is likely to strongly communicate that the marriage preceded the child’s birth in the context of a discussion about the couple’s adherence to certain social norms. On the other hand, if the same sentence appears in an exchange about a drop in the couple’s social engagements, the temporal reading of and might still be accessible, but is only weakly communicated. Importantly, both the level of meaning and the strength with which a content is expressed may have an impact on how committed a speaker will be perceived to be.

Given that a speaker risks suffering social repercussions when implying something false, would these repercussions be more severe when this content is communicated via a pragmatic enrichment rather than via an implicature? Or would they be worse off if the false content is strongly rather than weakly implicated? Alternatively, would the differences in speaker accountability emerge only when these different types of contents – weakly or strongly implicated or enriched – are denied? Here, we aimed to investigate the influence of the level of meaning and meaning strength on the speaker’s accountability, and whether they bring about similar effects on their message’s plausible deniability.

1.1 How might the Level of Meaning Impact Accountability and Plausible Deniability?

It has recently been proposed that commitment is stronger when meaning is fully linguistically encoded (explicitly communicated) than when it is merely implicated (Morency et al. 2008; Reboul 2017). Indeed, conversational implicatures have been found to foster less accountability than explicit contents, while explicit contents and presuppositions lead to similar levels of accountability (Hall and Mazzarella 2023; Mazzarella et al. 2018). Plausible deniability should be similarly influenced by the degree of explicitness of the conveyed meaning – i.e., by its level of meaning (Brown and Levinson 1987).

Pragmatic inferences are by definition cancellable – i.e., an utterance that implies a proposition p can be followed by the phrase ‘but not p’ without logical contradiction (Grice 1989; Levinson 2000). However, a proposition may be cancellable without being deniable – or at least, not plausibly so (Pinker et al. 2008): you may be able to logically cancel the non-literal content of your utterance without being in a position to plausibly deny intending it in the first place. If, when asked whether you know about a new policy introduced at a meeting, you answer “I wasn’t there” the implication that you did not know is clearly cancellable – there is no logical contradiction between not being present and knowing about something. Yet, it will be hard to deny that you intended to convey your ignorance of the new policy. Pragmatic phenomena can therefore be logically cancelled but whether, and how, they can be plausibly denied is a more complex issue that will depend largely on the properties of the context of utterance (Mazzarella 2021).

Of course, denying that some fully explicit content was intended is difficult – short of lying or claiming a mistake. The phenomenon of plausible deniability primarily applies to contents conveyed via pragmatic inferences, which seem much easier to revoke. Yet, these do not form a homogeneous category: the outcome of a pragmatic inference might be more or less explicit and thus, we believe, more or less plausibly deniable.

Since Grice (1989), most pragmatists consider there to be different types of implicit (i.e., cancellable) contents. Pragmatic enrichments,Footnote 1 such as the temporal reading of and, go beyond what is linguistically encoded in an utterance, but they are linked to linguistic terms or structures, in the presence of which they will often be derived (e.g., conjunction ‘and’ enriched to ‘and then’; disjunction ‘or’ enriched to ‘not both’; quantifier, ‘some’ or ‘most’ enriched to ‘not all’). In contrast, implicaturesFootnote 2, such as the implicit denial for a snack seen above, are entirely context-dependent additional propositions and do not depend on any specific linguistic feature. Their derivation requires taking into account the proposition explicitly expressed, as well as the context of utterance and the speaker’s intention (see e.g., Grice 1989; Levinson, 1983; Sperber and Wilson 1986/95).Footnote 3 Pragmatic enrichments are considered more closely related than implicatures to the linguistic form and the explicit content of an utterance: some theorists maintain that they are derived automatically, unless blocked by the context (Horn 1989; Levinson 2000), while others argue that, despite being pragmatically inferred, they are part of the explicit content of the utterance (‘what is said’, in Gricean terms) and contribute to its truth conditions (Carston 2002; Levinson 2000; Récanati 1993, 2001, 2004; Sperber and Wilson 1986/95). Theoretical debates notwithstanding, there is a general sense that pragmatic phenomena might be more or less explicit, with implicatures firmly lodged in the implicit camp and pragmatic enrichments verging toward, or achieving, explicitness (see, for example, Levinson 2000).

A large amount of research focuses on whether participants can distinguish enrichments from explicit content (‘what is said’ in Gricean terms) to determine whether they contribute to the truth-conditional meaning of the utterance. Enrichments were originally found to be judged as part of ‘what is said’ (Gibbs and Moise 1997), but the picture subsequently became more complex (Bezuidenhout and Cutting 2002). It seems that participants’ intuitions differ depending on the type of pragmatic inference (Doran et al. 2009) and the task used – for instance, the types of enrichments investigated by Doran and colleagues (2012) were neither consistently included nor excluded from ‘what is said’.

Relatedly, several recent studies investigated whether interlocutors consider false information conveyed via pragmatic inferences to be an instance of lying. This research on the comprehension of deceitful implicatures and enrichments yields mixed findings (for a study on the production of misleading enrichment and implicature, see Franke et al. 2020).

Weissman and Terkourafi (2019) show that participants consistently judged false implicatures to be non-lies, while some types of enrichments (e.g., upper-bounded interpretation of numerals) were more easily considered to be lies when the inferred meaning was false. Hall and Mazzarella (2023) also found that speakers suffered more reputational cost when they communicate false information via enrichments than when they communicated the same information via implicature. Yet, other studies suggest that even false implicatures may be considered eligible to be lies, and sometimes as much so as false enrichments (Antomo et al. 2018; Viebahn et al. 2018; Willemsen & Wiegmann, 2017). Furthermore, Wiegmann (2022) showed that many among the implicatures used by Weissman and Terkourafi (2019) were still considered to be cases of lying (and, thus, the speaker presumably conceived to be committed to the implicated content) provided that the intention to communicate the implicated (and deceptive) content was made salient.

Notwithstanding the fact that there are likely cultural differences in people’s intuition of what counts as a lie (e.g., Danziger 2010; Hardin 2010; Hruschka 2020), Reins and Wiegmann (2021) used a variety of particularly relevant measures to investigate the folk notion of lying. Following four scenarios involving a false implicature or enrichment, participants were asked whether they considered them to be lies, among other questions; these were compared to an additional set of measures including (among others) explicit questions about commitment (did the speaker commit themselves to the false enrichment/implicature) and deniability (could the speaker convincingly deny it). Lie responses correlated with those assessing commitment and deniability. Reins and Wiegmann found that false implicatures were mostly judged to be lies. However, attributions of lying, as well as commitment and deniability, were lower for implicatures than for enrichments. In a similar vein, Bonalumi and colleagues (2020) found that people considered unfulfilled promises conveyed via enrichment to have been broken, but not those conveyed via implicature.

Overall, although enrichments are pragmatic inferences – and thus cancellable – they often seem to be perceived as contributing to the utterance’s truth-conditions. As a result, they generally appear more difficult to deny than implicatures, which – it is generally agreed – are part of ‘what is implicated’. Additionally, as mentioned earlier, implicatures lead to less accountability than the explicit content of an utterance (Hall and Mazzarella 2023; Mazzarella et al. 2018). The two levels of meaning – enrichments and implicatures – should, therefore, modulate both accountability and plausible deniability differently (as suggested by Bonalumi et al. 2020; Reins and Wiegmann 2021; Wiegmann 2022).

1.2 How might Meaning Strength Impact Accountability and Plausible Deniability?

Another factor that can be linked to both plausible deniability and accountability is the degree of manifestness of what is communicated, i.e., its strengthFootnote 4. A pragmatically inferred part of meaning (be it an enrichment or an implicature) can be more or less strongly communicated; this will depend on how manifest the speaker made their intention to communicate it (Wilson and Sperber 2002), as well as how essential the pragmatic content is to understand the overall communicative act. First, a strongly pragmatically inferred content (enrichment or implicature) is a proposition the speaker intends to communicate, and they will therefore make this intention clear to their interlocutor, whereas their intention to communicate weaker contents is hazier and, as a result, less manifest to their interlocutor. Second, a strong implicature or enrichment is generally crucial to make the speaker’s utterance relevant in context, while the recovery of a weak one might be optional. Both aspects point towards strongly pragmatically inferred parts of meaning as being more accessible for the hearer than weaker ones.

Imagine two young parents arriving at home after braving a downpour and commenting on how they never want to leave the comfort of their living-room again. If one of them exclaims: “We’re out of milk!” the implicature that someone must go out to get milk for the child is strongly communicated. Indeed, it is difficult to see how the utterance would be relevant in this context if the implicature was not intended. On the other hand, other (weaker) implicatures might have been intended, or not – e.g., “our child drinks more milk than she used to” or “you forgot to put milk on the grocery list again”Footnote 5.

As Mazzarella (2021) notes, the strength of an implicit meaning will affect who endorses responsibility for the pragmatic inference. In the case of a strong implicature or enrichment, the speaker bears more responsibility since they make their intention to communicate it clearly manifest. Inversely, in the case of a weak implicature or enrichment the responsibility of deriving it lies mostly with the hearer (Sperber and Wilson 2006). This, in turn, should involve consequences for how accountable the speaker will be perceived to be: the stronger the implicature or enrichment, the more committed to it the speaker should appear (see also Boulat and Maillat 2023). Plausible deniability should be equally affected by meaning strength. Since the derivation of a strong implicature or enrichment is paramount to understanding the utterance, there is little room left in these cases for an alternative interpretation. Any attempt of denial would, thus, be less plausible, since there is only a narrow range of possibilities to re-construct the context – and thus providing an alternative, non-committal, interpretation of the utterance (Mazzarella 2021). On the other hand, weak implicatures and enrichments offer the speaker exactly this range of possibilities, suggesting that meaning strength is inversely connected to plausible deniability.

The hypotheses that stronger implicatures and enrichments should be more accessible than weaker ones, but also more committal, are mostly borne out by the handful of studies investigating meaning strength. Nicolle and Clark (1999) first found that strong implicatures prompted participants to select the implied meaning conveyed by the utterance as the best reflection of ‘what [it] said’. In contrast, with weaker implicatures, participants were more likely to select the minimal proposition of the utterance as representative of the explicit content (‘what is said’). Consistent with the hypothesis that meaning strength (modulated by relevance) influences accountability and plausible deniability, Bonalumi and colleagues (2020) found that the same explicit broken promise produced different social repercussions for the speaker depending on whether the recipient was known to rely on the promise made by the speaker. Finally, Sternau et al. (2015) investigated the deniability of enrichments, as well as weak and strong implicatures using an explicit question about deniability (akin to Reis & Wiegmann, 2021). Although their findings rely on participants’ a priori intuitions, rather than actual attempts of denial, they indicated that enrichments are perceived as less deniable than implicatures, and strong implicatures less so than weak ones.

Taken together, these results suggest that strong implicatures are more easily included into the explicit content, have higher impact on accountability and might be harder to deny compared to weaker ones. Note that since meaning strength is a feature of enrichments and implicatures alike (Clark 2013), it should modulate commitment and plausible deniability for both phenomena (Mazzarella 2021; and Sternau et al. 2017 both also make this prediction for plausible deniability).

1.3 The Present Study

A message can be conveyed both with different degrees of manifestness, i.e., more or less strongly, and with different degrees of explicitness, i.e., graded levels of meaning (see Fig. 1). As reviewed above, both factors might affect the extent to which a speaker is committed to the content of her utterance, and consequently how easily that commitment is deniable. Here, to further understand the attribution of commitment (and how speakers strategically attempt to avoid it), we aimed to directly test the effects of meaning strength and level of meaning on deniability. Specifically, we sought to test the following hypotheses:

1.

Strongly implicated contents should lead to higher accountability and be more difficult to deny than weakly implicated contents.

2.

Enrichments should lead to higher accountability, and be more difficult to deny, than implicatures.

Fig. 1

The degree of explicitness (x-axis) interacts with the degree of manifestness (y-axis): fully linguistically encoded contents, as well as enrichments and implicatures, can be more or less strongly/weakly communicated

We tested these hypotheses in an online experiment. The experiment itself – the Commitment Experiment – was preceded by a Norming Study to ensure participants interpreted the materials with the pragmatic inferences and drew comparable intended meanings in each experimental condition. Participants were presented with written scenarios in which speakers used different levels of meaning (Enrichments or Implicatures) with different strengths (Weak or Strong) to make a commitment. Meaning strength depended on how manifest the implied content was in the scenario. Implicatures were always determined by the interaction between the utterance and the specific context, while enrichments were of four types: temporal conjunction enrichment (‘and’ meaning ‘and then’), the enrichment of the conditional (‘if’) to a biconditional (‘if and only if’), as well as the scalar inferences linked to the quantifier ‘some’ (‘not all’) and to disjunction (‘or’ meaning ‘not both’; for discussion of these phenomena see for instance, Levinson 2000; Carston 2002; Noveck 2004). We chose four different types of enrichments to make sure our findings could generalise to enrichments as a category and were not limited to a single phenomenon. We took care to pick phenomena generally agreed to be enrichments across theoretical frameworks – i.e., all of the phenomena we chose are considered as enrichments or as generalised conversational implicatures (GCIs) by authors such as relevance theorists (Sperber and Wilson 1986/95; Carston