Communicating Likelihood and Managing Face: Can we Say it is Probable when we Know it to be Certain?

Different functions can be performed by probability phrases such as: ‘it is probable/possible/likely that x.’ Mainly, speakers may communicate a vague judgment about the likelihood of event x, or they may wish the recipient to focus on reasons for the occurrence of event x. We argue that there is another communicative function which has yet to be documented, namely, the facemanagement function. Such function consists in mitigating threat to the addressee when x is a criticism or an imposition. Data show that the phrases ‘possibly’ and ‘probably’ are indeed understood differently (have different membership functions) depending on whether they modify neutral or face-threatening contents. We consider the potential misunderstandings and judgmental mistakes that may arise from ambiguity about which function of verbal uncertainty is being performed. Functions of Verbal Uncertainty Imagine a conversation between two very close friends, one of whom is complaining that she gets little attention from men. The other friend then replies: ‘It is probable that your bad breath makes men uncomfortable.’ What does she mean by ‘probable’? From the onset of the study of the meaning verbal probabilities, researchers have proposed that expressions such as it is probable that x or it is possible that x are used to express, albeit vaguely, a judgment about the likelihood of the proposition or event they predicate (e.g., Lichtenstein & Newman, 1967; Wallsten et al., 1986). Thus, the sentence ‘it is probably going to rain tomorrow’ means that the speaker has some intermediate confidence in the prediction that it is going to rain, a confidence that could perhaps be expressed as a 70% chance, but definitely not as a 99% chance. Starting from the assumption that probabilistic phrases are vague concepts in the sense of fuzzy set theory (Zadeh, 1965), Wallsten et al. (1986) and Rapoport, Wallsten, and Cox (1987) suggested that the meaning of a probability phrase could be represented by its membership function. The membership function of any given phrase assigns a number to each value on the probability line [0, 1] that represents its degree of membership in the concept defined by the phrase. Degree of membership is usually expressed as a real number from 0 to 1, such that memberships of 0 denote probabilities that are absolutely not in the concept, and memberships of 1 denote elements that are perfect exemplars of the concept. All other values represent intermediate degrees of membership. The peak of a membership function is the probability (or the mean of the probabilities) at which the function reaches its maximum value. A number of studies (reviewed in Budescu & Wallsten, 1995, and Wallsten & Budescu, 1995) have shown most probability phrases to be single peaked. For instance, the membership function of ‘possible’ increases monotonically until it peaks at around .7, then decreases monotonically. Only very specific phrases, such as ‘certain’ or ‘impossible’ monotonically increase or decrease all the way through the probability interval [0, 1]. Membership functions indicate the extent to which each probability value may ‘typically’ be communicated by a given phrase. The possibility that a given phrase may translate into different probability values at different times is thus captured by this approach. Membership functions, however, are taken to portray the meaning of probability phrases independently of the context in which they are used. In other words, this approach precludes the possibility that the membership function of a given phrase would vary as a function of the context in which it is evaluated. Teigen and Brun (1995, 1999) proposed that probability phrases can not only convey meanings of vague likelihood but also have communicative functions that are embedded in them. Such a communicative function, directionality, invites the hearer of the message to focus on the occurrence or the non-occurrence of the event being predicated, depending on the polarity of the phrase used by the speaker. For example, saying ‘it is unlikely that it will rain tomorrow’ rather than ‘there is a small chance that it will rain tomorrow’ focuses on the absence rather than the presence of rain. However, Budescu, Karelitz, & Wallsten (2003) showed that phrases’ directionality could be predicted from properties of their membership function. Consistent with the authors’ predictions, positive phrases were found to be negatively skewed and have peaks above 0.5 whereas negative phrases tended to be positively skewed and have peaks below 0.5. Moreover, the authors demonstrated that this relation was invariant across contexts. Intuitively, however, neither of these interpretations of the meaning of verbal probability phrases seems to account for the meaning conveyed by the speaker who says: ‘It is probable that your bad breath makes men