1 Introduction

From Hamblin’s work on Fallacies (1970), the relationship between the analysis and evaluation of arguments and pragmatics has been widely acknowledged in argumentation theory (van Eemeren and Grootendorst 1984, 182; Walton 1989; Walton 1990). Researchers have focused on the specific pragmatic concepts such as context (Tindale 1999), common ground (Hamblin 1970, 237–238), speech acts (van Eemeren and Grootendorst 1984; Budzysnka and Reed 2011; Corredor 2017; Lewinski and Aakhus 2022), and interpretative reasoning (van Eemeren and Grootendorst 1982; Hinton 2020) to develop approaches that can account for how arguments can be used strategically and manipulatively. However, despite the growing interest in the crucial interface between pragmatics and argumentation, the dialogue between argumentation theory and linguistic or philosophical pragmatics is still limited (for the most recent developments, see Hinton 2023; Oswald 2023). Pragmatic theories are used in argument or argumentation analysis, but at the same time the latter poses crucial problems to the existing pragmatic models, as the consideration of different types of real-life dialogical settings and purposes and the specific goal of providing support to a specific viewpoint require theoretical tools that combine different disciplines.

One of the most complex notions in the pragmatic-argumentation interface is presupposition. In argumentation, this concept emerges explicitly very rarely, especially in relation to the fallacies of loaded question, many questions, and false dichotomy (Walton 1981; Moldovan 2022). In pragmatics, it is one of the most debated and controversial topics that has been addressed from a linguistic, semantic, and pragmatic perspective (Levinson 1983, chap. 4), leading to a multiplicity of approaches, theories, and problems. If we consider its shared definition, namely a kind of implication that suggests that the truth of the presupposed content is taken for granted and treated as uncontroversial (Chierchia and McConnell-Ginet 1990, 23), presupposition becomes pervasive of every argumentative discourse. It becomes an essential feature of tacit premises (van Eemeren and Grootendorst 1982; Lombardi Vallauri and Masia 2014) and is involved in several manipulative strategies.

Despite its importance, presupposition has been almost neglected by argumentation scholars, and confined to the study of very specific tactics that attract very little attention. The most problematic aspect is that the immense variety of theories and models cannot fully explain the complexity of the data considered in argumentation and cannot provide clear answers to some crucial questions. How can presupposition be used to manipulate discourse? What are its effects? How can it be evaluated? This paper attempts to provide an overview of the problems involved in addressing these issues by presenting the possible contributions of pragmatic models to argumentation analysis, and the new perspectives that the latter opens. After introducing the existing approaches on presupposition, the dialectical perspective will be explained, showing how it can be used as an instrument for analyzing and evaluating argumentative moves, and in particular the mechanism of distinct potentially deceptive tactics that can be found in the logical literature under the label of “fallacies.”

2 What is Presupposition? The Semantic Approach

A presupposition is commonly defined by considering two aspects of this phenomenon, namely its linguistic and pragmatic dimensions (Chierchia and McConnell-Ginet 1990, 23):

Like entailment, presupposition involves a kind of implication. If a sentence A (or its use or user) presupposes B, then A implies B, suggests that B is true. But presupposition involves more than simple implication: if A presupposes B, then A not only implies B but also implies that the truth of B is somehow taken for granted, treated as uncontroversial.

From a semantic perspective, presuppositions are regarded as a special kind (or family) of implications (Chierchia and McConnell-Ginet 1990, 24) that seem to be built into linguistic expressions, i.e., they are conventionalized. This conventional status explains an aspect of their behavior, namely the fact that they are triggered also when the logical predicate of the sentence is denied or questioned—or more precisely, they result from different uses of a sentence (such as for affirming, denying, supposing, or questioning) (Chierchia and McConnell-Ginet 1990, 24).

From a semantic perspective, presuppositions have been incorporated into truth-conditional theories as a special kind of entailment (Wilson 1975, 43–44), which survives negation and results in the lack of verifiability of the sentence in case its presuppositions are false (for example, in the famous case of “The king of France is bald” stated in the XX century). Thus, “if p semantically presupposes q, then p always semantically presupposes q (providing that p is not embedded in a linguistic environment—other than negation—in which p fails to entail q)” (Levinson 1983, 200). The problem of presupposition failure is resolved through the lack of a truth value of p: for example, if the referent of the subject of a sentence (or more precisely, the use of a sentence in a context, see Strawson 1950, 1952; Karttunen 1973; Kempson 1975) does not exist, the sentence cannot be verified—“the question whether the statement is true or false doesn’t arise” (Strawson 1964). Since the sentence is not verifiable, its use is spurious, and can be replied only by rejecting the assertion (“But there is no king of France”) (Strawson 1950, 333).Footnote 1

The semantic account of presupposition tends to combine two distinct aspects: the truth-conditional account (semantics deals with the truth-conditions of sentences), and the linguistic competence of the speakers (conventional aspects of meaning that can be studied independently of the context) (García-Carpintero 2006, 47; García-Carpintero 2016, 38). This twofold role of semantics resulted in several problems related to the use of presuppositional sentences. First, this approach cannot account for the disappearance of presupposition under a specific use (metalinguistic) of negation (“John doesn’t regret having failed, because in fact he passed”), and in conjunction with a sentence that qualifies modally the presupposition (suspension) (“John has stopped smoking, if he ever did/and maybe he never did”) (Horn 1972, 17–19; Horn 1985; Horn 1989, 365–370). Second, presuppositions can be contextually cancelled in specific contexts in which the available “common knowledge” prevails over the presupposed content, such as in the following case (Levinson 1983, 187):

  1. (1)

    a. Sue cried before she finished her thesis.

    b. Sue died before she finished her thesis.

Here, the presupposition “Sue finished her thesis” is triggered by the use of the temporal clause; however, in (1b) this presupposition is cancelled (or “evaporates”), as it is contradicted by the assertion that Sue died at a time preceding her finishing the thesis. This information and the encyclopedic knowledge that dead people cannot write theses, leads to an inconsistency that is avoided by cancelling the presupposition.

3 Pragmatic Presupposition

The notion of pragmatic presupposition has been developed independently in the fields of linguistics and philosophy to capture the relationship between the speaker and an assumption that is presented as a pragmatic constraint on the use of a sentence . (Levinson 1983, 205; Stalnaker 2002; Allan 2013) or the further development of the dialogue (Ducrot 1966, 1969, 1972a).

3.1 Presupposition as an Attitude

From a philosophical perspective, a pragmatic presupposition is an attitude (Simons 2003) towards a specific proposition, which is taken for granted and assumed to be granted by the others involved in that context (Stalnaker 1974, 472). For this reason, pragmatic presuppositions can be manifested through semantic presuppositions (triggers), but also other elements of communication. For example, the alternatives in a question represent its presupposition; however, the possible answers can be determined contextually, and not semantically. For example the presuppositions (alternatives) of a question such as “Who is going to win the next presidential election?” asked in the US in 2020 are different from the ones characterizing the same question asked in France in 2022; however, this presupposition is determined contextually (Stalnaker 1973, 449; Atlas and Levinson 1981, 4).

This approach to presupposition avoids the problem of verification. Pragmatic presuppositions express the speaker’s attitude, and for this reason the presupposed contents do not need to be true—they can be unknown or even false (Stalnaker 1970, 281). What matters is that they are treated as (or pretended to be) accepted and uncontroversial by the speaker. Thus, the utterance of, “The king of France is magnificent” during the French Republic involves a pretense of common ground (France has a king; Robespierre is the king) that is commonly accepted as false (Donnellan 1966, 290–291; Ducrot 1966, 42). However, despite the “falsity” of its presupposition, the utterance can be assessed—and result in dire consequences for the speaker.

The concept of pragmatic presupposition rests on the speaker’s attitude, namely his or her “taking for granted” the presupposed content (Stalnaker 1974, 472). Stalnaker acknowledged that presuppositions are not mental states and do not require necessarily either the interlocutors’ knowledge of the presupposed proposition, or its truth (Stalnaker 2002, 704). However, how to account for how presuppositions are used? Different explanations have been advanced in linguistics and philosophy to attempt to specify what a presuppositional attitude amounts to, and how it can modify the dialogical exchange. Three accounts are particularly interesting for argumentation theory: the classical epistemic perspective, the illocutionary view, and the dialectical approach, which will be all presented in the next section.

3.2 The Epistemic Approach

The epistemic perspective can be considered as the classical interpretation of the notion of pragmatic presupposition in terms of “common ground” (Beaver 1997, 2439) and the interlocutors’ beliefs. The notion of “taking for granted” is translated as commonality of beliefs or even knowledge (Hamblin 1970, 237–238): by presupposing a proposition, the speaker treats some contents as part of the common or mutual belief, which corresponds to the beliefs that the participants to a conversation share and recognize that they share (Stalnaker 2002, 704). This view has a theoretical and an empirical limitation. From a theoretical perspective, common ground corresponds to an iterated belief (or knowledge) (p is common belief if an only if all believe that p, and all believe that all believe that p, etc.), which results in an infinite regress (Clark 1996, 99; García-Carpintero 2016). From an empirical perspective, speakers can presuppose a proposition known not to be in the common ground, such as in the following case (Stalnaker 1973, 449):

  1. (2)

    A says of the new secretary, “Jennifer is certainly an attractive woman.”

    B replies: “Yes, her husband thinks so too.”

B’s reply is a clear example of informative presupposition (Burton-Roberts 1989, 26; Abbott 2008; von Fintel 2008): B presupposes that Jennifer is married, but at the same time knows and presumes that information is not shared by A.

To address this imperfect epistemic correspondence between presupposition and common ground, the idea of “accommodation” was developed (Lewis 1979). Accommodation can be described as a process of charitable adjustment of the common ground that takes place when the hearer recognizes that the speaker takes p as common ground and adds p to his background knowledge. The problem with this common ground adjustment rests in its constraints. First, the hearer needs to be able to reconstruct or retrieve the presupposition (Strawson 1964, 106; Asher and Lascarides 1998, 277). For example, if the hearer cannot retrieve the referents in a statement such as “Rob was at the fair,” accommodation is impossible, resulting in an inappropriate utterance (Clark and Brennan 1991, 226). Second, the accommodated proposition needs not to conflict with the hearers’ existing “beliefs” or “assumptions”—in an epistemic or dialectical sense. Thus, a presupposed proposition can be accommodated because the interlocutors are agnostic as to its truth (and trust that the speaker tells the truth), or they do not want to challenge the speaker to allow the conversation to continue smoothly (von Fintel 2008, 145).

3.3 The Illocutionary Approach

According to the illocutionary approach, the (pragmatic) presuppositional attitude is an assumption, or a presumption, or even a pretense that a proposition is mutually believed to be true (Stalnaker 2002, 704) (or uncontroversial, see Grice 1989, 274; Atlas 2005, 142). This “assumption,” however, defines the boundaries of the speaker’s linguistic behavior, which cannot conflict with, or state what is presupposed (Stalnaker 1970, 280; Stalnaker 1974, 473). Thus, it would be inappropriate to utter:

  1. (3)

    “The king of France is bald.”

in a context in which the existence of the king of France is not part of the presumed background information (see Donnellan 1966, 288). Presupposition is a requirement of the foregrounded act, and can be considered itself as a kind of act (Ducrot 1972a, 91), consisting in behaving as if the truth of the presupposed proposition is taken for granted (Stalnaker 1973, 451). On Ducrot’s perspective, this act sets the conditions of the further possible dialogue by constraining the possible linguistic moves that can be performed (Ducrot 1972b). Thus, in order to continue the dialogue started by (3), the hearer needs to accept the existence of the king of France (Ducrot 1968, 87); otherwise, he simply terminates the dialogue game by rejecting the presupposition and, in case, starting a different (meta)dialogue on the acceptability of the presupposed content.

4 The Dialectical Approach

In the dialectical perspective, the notion of “common ground” (or “common knowledge”) is replaced by the epistemically weaker concepts of “non-controversiality” and “commitment” (Geurts 1999). This approach tries to unveil the reasons for taking a proposition for granted, reconstructing the hearer’s and the speaker’s reasoning for establishing their attitude towards a presupposed proposition—namely the interpretative process and the explanation of speaker’s behavior.

4.1 Explaining the Speaker’s Dialectical Behavior: Presuppositions as Commitments

In his theory of polyphony, Ducrot treated presuppositions as a collective voice, to which both the speaker and the hearer belong (in their capacity as the locuteur and the allocutaire). In this fashion, the speaker “dilutes” his dialectical responsibilities, and at the same time makes it harder for the hearer to reject a view attributed to the general public (Ducrot 1982; Nølke 1994, 2006; Günthner 1999).

From a dialectical perspective, this approach has been developed by considering presuppositions as an instrument for modifying the dialectical obligations (Geurts 1999, 4; Macagno 2018), or “commitment store” (Ginzburg 1994; Walton and Krabbe 1995, 23–24; Ginzburg 1996). Presuppositions are regarded as “dark-side” commitments (Walton and Krabbe 1995, 124–126), namely implicit commitments, resulting not from what is explicitly said, but rather what is implicitly communicated (van Eemeren and Grootendorst 1983, 220). Building on this view, Walton noticed that pragmatic presuppositions modify the interlocutors’ commitments in a specific way. In addition to committing the speaker, in some contexts of dialogue they involve a shift in the burden of proof: the interlocutor has the burden of refuting or rejecting the presupposition, otherwise it goes into place as a commitment (Walton 1993, 138). This view is based on a normative approach to dialogue games, which seldom represent what happens in real dialogues. However, even if presuppositions do not necessarily result in effect on the interlocutor’s commitment store (also acknowledged by Ducrot), they can be regarded as an attempt to introduce (illegitimately) unshared commitments as they were part of what is commonly (or has been previously) accepted. The success of this attempt and the interlocutor’s available ways to reject the unshared implicit commitment depend on the type of communication, the relationship between the interlocutors, and several other factors.

The effects of presupposition on the interlocutors’ commitments can be represented in the following Fig. 1, which depicts the two distinct scenarios in which the presupposed content is either already shared, or not accepted by the interlocutor. The message (like all the other following examples) is taken from a Tweet by the former Italian minister for interior affairs and leader of the right-wing party Lega (translation mine),Footnote 2 and relies on the concept of “community center” (in Italian, “centro sociale”) namely buildings that in Italy are (often illegally) squatted and devoted to activities for the community. Salvini uses the term metonymically to refer to the squatters, after twisting it (“anti-community center— in Italian “centro a-sociale”) to convey a negative value judgment on them.

Fig. 1
figure 1

Presuppositions and dark-side commitments

Full size image

Example 1

In Rome, the plan for removing the squatters moves on without interruptions, also despite those “anti-community centers” who prefer drug dealers to policemen!

Here, the message modifies the interlocutors’ commitment store in three distinct ways. Considering the commitments reconstructed in Fig. 1 below, Salvini is explicitly committed only to 1 (light-side commitment), which can be accepted, doubted, rejected, or simply conceded by the audience. The problems emerge with the dark-side commitments, which are either commonly accepted by the readers (no. 2 and 3) or unshared (no. 4, 5, and 6). While the message reminds the readers of the presumably shared dark-side commitments of the first kind, it attempts to illegitimately introduce the unshared implicit commitments in the audience’s commitment store. The speaker attempts to unilaterally change the interlocutor’s commitment store, presenting controversial claims as part of the commonly shared opinion (the commitments that can be considered as unproblematic within a given community).Footnote 3

The role of presupposition in introducing (or at least attempting to introduce) new commitments or bringing to light existing ones was explained by Walton through the notion of act of presumption. On this view, by using a presupposition, the speaker advances the presumption that s/he has reasons for concluding that the interlocutor accepted the presupposed content (Walton 1993, 142). The illocutionary dimension of presupposition is combined with a dialectical one, consisting in the activation or imposition of a defeasible generalization that holds until contrary evidence is provided (Ullman-Margalit 1983; Macagno and Walton 2012; Godden 2017). By triggering a presupposition (for example, by using a definite description such as “The king of France is bald”), the speaker either activates a presumption based on evidence from the context (for example, normally French citizens are committed to France being a Republic, and my interlocutor is a French man) or introduces a new presumption, trying to impose a dark-side commitment. In some contexts of communication or dialogue, the rejection of this implicit move can result in a burden shifting, as the interlocutors may need to justify their rejection of an allegedly commonly accepted proposition.

4.2 The Hearer’s Perspective: Presuppositions as Interpretative Inferences

Considering the hearer’s perspective, presuppositions are analyzed as the result of a specific interpretative practice. They are linguistically signaled as “backgrounded” (Black 1962, 61–62), and thus expected not to be questioned by the hearer, and added to the “store of noncontroversial information” if they are not already accepted (Chierchia and McConnell-Ginet 1990, 23; Atlas 2005, 144). Thus, for the hearer a pragmatic presupposition is an attitude towards the speaker’s utterance (or argument, in case of implicit premises) consisting of supplying the presupposed content and treating it as noncontroversial (van Eemeren and Grootendorst 1984, 132). This attitude is the result of an interpretative practice, and more precisely an inference aimed at explaining  the speaker’s behavior (Stalnaker 1974, 473). The explanandum in this case is the speaker’s use of an utterance type that generally carries a presupposition; the explanation is that when this type of utterance is used, the speaker is (defeasibly) presuming that the presupposed content is uncontroversial (Stalnaker 2002, 705).

This “inductive” (as Stalnaker labels it) interpretative inference has been analyzed as a conversational implicature in Pragma-Dialectics, partially building on Grice’s perspective. According to Grice, presuppositions are defeasible (cancellable), non-detachable, and can be drawn through an inferential process—thus qualifying as conversational implicatures. However, they carry an additional dialectical attitude: they are presumed to be accepted by the interlocutor without the need for further reasons (Grice 1989, 474). Van Eemeren and Grootendorst developed the same analysis of a specific type of presupposition, the one triggered by “argumentative” connectors such as “therefore” or “but” and normally referred to as “unexpressed premise.” On their view, the hearer reconstructs the unexpressed premises by following a defeasible inferential pattern aimed at explaining the speaker’s behavior of stating a defective argument, in which a premise is missing. By relying on the presumptions that the speaker is cooperatively engaged in an argumentative discussion, and that the addition of a premise would “validate” the argument, the hearer can (abductively) infer the unstated proposition (normally treated as a presupposition, see van Eemeren and Grootendorst 1984, 129–131; Rigotti 2005).

This explanatory inferential reasoning is grounded on premises commonly considered as presumptions (Donnellan 1966, 291–292). The use of a presupposition (Donnellan analyzes the presuppositions resulting from the use of definite descriptions) triggers the presumption that the speaker believes that the presupposed referent exists, or that the presupposed proposition is true. The provisional, defaultive nature of these generalizations was developed by interpreting the notion of common ground in dialectical terms as a “conversational record,” namely the set of the participants’ presumptions concerning what is already established or public (Thomason 1990, 337). From the hearer’s perspective, this approach explains the phenomenon of informative presuppositions and accommodation as “background implicatures:” the hearer (a) recognizes the speaker’s intention of acting as if the previous state of the record involved a specific presumption, and (b) modifies his or her conversational record accordingly to meet the speaker’s implicit request of “resetting the record” (Thomason 1990, 352).

5 Developing the Dialectical Approach: The Reasonableness of Presupposition

The dialectical approach to presupposition seems to be divided between two distinct positions. On the one hand, presupposition is regarded in illocutionary terms as an act of presuming and introducing (or attempting to introduce) commitments. This view, however, results in an apparent freedom of presupposing. On the other hand, presupposition is analyzed from an interpretative perspective as an explanatory inference, which, however, fails to account for the hearer’s committal to the presupposed content and to set the boundaries of the possibility and reasonableness of presupposing. These two perspectives can be conciliated if we consider presupposition as a specific presumptive inference drawn by the speaker and the hearer. On this view, presupposition is represented as the conclusion of a pragmatic inference that can be based on different types and levels of presumptions, and that can be evaluated as acceptable or unreasonable.

5.1 Accepting, Conceding, Rejecting Reasonable or Unreasonable Commitments

As pointed out above, the possibility of presupposing does not correspond to the absolute freedom of presupposing. In particular, the process of accommodation underscored how the possibility of modifying the common ground is constrained by specific conditions that account for presuppositional failures resulting from the hearer’s impossibility of retrieving or accommodating the presupposed content (Lewis 1979; Simons 2003; Atlas 2008; von Fintel 2008). From a dialectical perspective, the picture is more complex both for successful and unsuccessful presuppositions. The first element of complexity are varieties of commitments and degrees of commitment: committing provisionally to a possibly acceptable presupposed content is different from full commitment.

A second crucial complication consists in the fact that the conditions of accommodation explain presuppositional failures as a unilateral phenomenon – as if the hearer could decide not to accept a presupposed content without providing reasons. If we consider presuppositions as part of a talk exchange, we need to analyze the reasons for rejecting them, which leads to inquiring into the speaker’s reasons for presupposing and the distinction between failed and absurd presuppositions (Macagno 2015; Macagno 2018; Macagno 2023). Thus, it is possible to draw a distinction between the following cases:

  1. (4)

    “Is the king in his countinghouse?” (said in a context in which the man occupying the throne is a usurper)

    (a) “Is the king in his countinghouse?” (headline of a newspaper article)

    (b) “Is the king in his countinghouse?” (asked in a context in which the man occupying the throne is a usurper, to a hearer who has publicly refused to acknowledge him as a king)

    (c) “Is our king in his countinghouse?” (asked by an Italian citizen to a friend)

The three cases differ at the level of the types of commitment and reasonableness of presupposing. Example (4) above represented a case of a question with a presupposition considered to be false, but retrievable by the interlocutors. From a commitment perspective, the hearer can reconstruct the presupposition – thus accommodate it – and even answer the question in a context of dialogue which allows commitment to be conceded for the sake of the argument (Walton 1993, 135). For example, in an information seeking dialogue, what matters is the provision of the relevant information (the location of the entity referred to as the king), and not the hearer’s viewpoint on his legitimacy. In this case, the latter can assume temporarily the commitment or attribute it to the speaker’s commitment store only, without incurring any responsibility. However, in different context of dialogue—such as an interrogation or some stricter persuasion dialogues—the failure to reject this commitment could be interpreted not as a mere concession (for the sake of the argument), but full acceptance.Footnote 4 The dialogical ambiguity of example (4) is not present in (4a), which the hearer can recognize as a purely information sharing interaction. For this reason, even if the referent of the king cannot be identified, the hearer can concede the commitment that there is a king, waiting for further confirmation or clarification.

The two first examples represent different aspects of concession of commitments. In contrast, examples (4b) and (4c) represent two different situations in which the presupposed content conflicts with the hearer’s commitments, which can result in the need to reject the dark side commitments advanced through these moves. However, there is a difference between them that can be explained in terms of the speaker’s reasoning underlying his or her use of presupposition. In (4b), the speaker is presuming that the existence of a king, or the role of a specific individual as the king, is commonly accepted within a community, even though contrary evidence concerning the hearer’s commitments is available. In (4c), instead, the speaker is using a presumption that is not commonly accepted, namely that “Italians commonly accept that Italy has a king.” While the former is a case of a simply unaccepted presupposition, the latter illustrates the mechanism of unreasonable presuppositions. The failed use of a presumption (namely the use of a presumption that is subject to default in the given circumstance) is distinguished from the use of an unacceptable presumption.

In between these two cases lies a specific context of use of (4c), i.e., the case in which the interlocutor is presumed to ignore Italy's government type. Here, the speaker uses a presupposition that is only contingently reasonable, but unreasonable in a normal setting. The hearer can accept the presupposition as s/he has no evidence for rejecting it; however, at the same time the speaker’s move is based on a presumption that is not otherwise shared.

5.2 Presumptive Reasoning and Reasonableness

As the aforementioned examples show, presupposition has not a single and uniform effect on the interlocutors’ commitments. In the classical persuasive dialogue context, presuppositions can be represented as attempts to introduce new commitments when they are not already shared (see Fig. 1). However, the picture becomes more complex in other contexts of dialogue. In some circumstances, presuppositions are merely proposals of concessions; in others, they advance personal commitments. Moreover, the speaker’s presupposed commitments vary depending on their reasonableness. For these reasons, the interlocutor’s inference responsible for retrieving the dark-side commitments (interpretative side) needs to be combined with the speaker’s grounds for presupposing (explanatory side).

The explanatory and interpretative dimensions of presupposition can be represented by a specular reasoning grounded on the notion of presumption (Donnellan 1966; Strawson 1971, 58–59; Kempson 1975, 166–167). Presumption is commonly regarded as the conclusion of a defeasible scheme of reasoning (Walton et al. 2008) called “presumptive reasoning,” and described as follows (Walton 1993; Rescher 2006, 33):

Premise 1:

P (the proposition representing the presumption) obtains whenever the condition C obtains unless and until the standard default proviso D (to the effect that countervailing evidence is at hand) obtains (Rule)

Premise 2:

Condition C obtains (Fact)

Premise 3:

Proviso D does not obtain (Exception)

Conclusion:

P obtains

Speaker’s presuppositions can be considered as the conclusion of presumptive inferences, which can be assessed as reasonable or not. In particular, the speaker’s decision to take some propositions for granted can be explained as based on the prediction of their acceptance by the hearer. For this reason, s/he is relying on some regularities or conventions that work as generalizations supporting educated guesses concerning linguistic meaning, pragmatic goals, or the interlocutor’s knowledge and values. The structure of this type of reasoning can be compared to the reasoning from cause to effect (for the relationship between causal reasoning and statistical belief prediction, see Weber 1989), grounded on the generalization that “generally, if A occurs, then B will (might) occur” (Walton et al. 2008, 168). Clearly, no (deterministic) causal relationship can be claimed in case of presuppositions; however, linguistic, pragmatic, and social conventions and observed regularities (which we generally refer to as “presumptions”) are used to predict the interlocutor’s possible interpretative behavior and his background knowledge (Macagno and Walton 2015).

This presumptive inference is defeasible, as it depends on the acceptance of Rule of presumption (Premise 1), the occurrence of the condition C, and the lack of the proviso D. Thus, if we consider the aforementioned examples, we notice that while (4b) represents a substantial flaw of the reasoning, as it fails to take into account the existence of D, (4c) incurs a more serious failure, as the very rule is unacceptable.

The regularities and conventions underlying the speaker’s educated guesses can be of different nature and have different degrees of specificity. The types of presumption can be summarized in the following macro-categories (Macagno 2018):

P0:

Pragmatic presumptions: Representing the relationships between a move and the speaker’s intentions in a dialogue (e.g., in deliberation dialogues, moves are normally proposals, acceptance, and grounded rejections).

P1:

Linguistic presumptions: Representing commonly accepted meaning of lexical items (e.g., community center is commonly used to refer to structures normally autonomously managed aimed at providing socially useful services, including cultural and recreational ones).

P2:

Encyclopedic presumptions: Information considered to be shared because it concerns individuals, facts, events, and descriptions of the world as socially conceived (e.g., normally Italians accept that Italy is a republic; normally Italians are accepted as pasta eaters).

P3:

Value presumptions: Expectations about preferences (e.g., normally education and knowledge are positive in Italy).

These presumptive rules can be stronger or weaker depending on their specificity, namely whether they concern the interlocutor directly (this person normally uses a specific term X with meaning Y), or indirectly, as a member of a more or less generic culture (members of group Z use a specific term X with meaning Y) (Clark 1996, 113–115; Kecskes 2013, 4; Kecskes and Zhang 2013).

The distinction between the different types of presumption can explain the presuppositional reasoning and effects underlying Example 1. The first problem for the analysis of presuppositions consists in determining the type of dialogue the interlocutors are engaging in. However, at this level this message is ambiguous, as Salvini is acting both as a minister (thus presumably justifying his decisions in a persuasion dialogue) and as a political leader rallying his voters and attacking the opponents (thus presumably venting his own views in a kind of eristic dialogue). Depending on these pragmatic presumptions (P0), Salvini’s presuppositions can be claimed as an illicit attempt to introduce unshared dark-side commitments, or simply manifesting his backgrounded views.

In the first scenario, Salvini is acting based on different kinds of presumptions. First, he is presuming at a linguistic level (P1) that the newly coined word (anti-community center—“centro a-sociale”) has a shared meaning. Second, he acted based on several encyclopedic presumptions (P2): Italians are presumed to accept/know that (a) squatters have occupied some buildings illegally; (b) people living in community centers are hindering the eviction process; (c) people living in community centers prefer drug dealers to policemen; (d) drug dealers live in these squatted buildings. These P1 and P2 presumptions are self-contradicting, as the speaker is introducing a new term (not presumable as shared) and providing a new specific account of a very recent event, which cannot be already accepted by all the readers. Finally, a value generalization is used (P3), namely that people living in community centers are commonly considered as despicable and uncivil—which can be shared among some readers, but not by the whole population (which includes left-wing voters).

In this scenario, Salvini’s linguistic behavior can be analyzed and assessed from an argumentative point of view as based on unreasonable inferences. Salvini uses presumptions that are defeated by available evidence or by conflicting presumptions, resulting in conclusions that do not follow from the premises. In this sense, the aforementioned uses of presuppositions can be explained in terms of weak or rather deeply flawed reasoning, and thus potentially manipulative moves. From a dialectical perspective, under some conditions the presumptions on which these presuppositions are based can lead to an illicit modification of the audience’s commitments. This can happen in cases in which the readers completely ignore the situation, rely on hasty generalizations concerning left-wing protesters, or trust completely a minister who interacts with his citizens.

6 Presuppositional Fallacies

As pointed out above, presuppositions are fundamental instruments for managing dark side commitments, and, at the same time, dangerous tools of manipulation. From a dialectical perspective, through them a speaker can attempt to introduce a new commitment in the interlocutor’s commitment set without taking direct responsibility therefor (Black 1962, 61; Lombardi Vallauri and Masia 2014). As Ducrot claimed, presupposing amounts to attributing the responsibility of a content to a collective voice, to which the speaker belongs (Ducrot 1984, 231). This communicative (polyphonic) aspect of presupposition has direct implications for argumentation. By presupposing, the speaker can avoid the burden of proving the presupposed contents, and at the same time tries to place the burden of disproving what is allegedly commonly accepted on the interlocutor.Footnote 5 However, how are presuppositions used to manipulate discourse? How is it possible to detect and describe the types of manipulation through presuppositions?

To address this challenge, it is useful to map the potentially deceptive argumentative strategies that are based on unshared presuppositions. To this purpose, the notion of “presuppositional fallacy” will be used. “Fallacies” are here intended as instrumental techniques “for carrying out goals in an argumentative interpersonal exchange” (Walton 2003, 3), namely as moves used for presenting a “contentious argument” or defending an implicit conclusion (Hamblin 1970, 66). The presuppositional fallacies presented in the sections below combine different manipulative argumentative moves analyzed in the logical tradition, showing their pragmatic dimension and dialectical effects.

6.1 Loaded (Many) Questions

In the logical tradition, the most studied and famous presuppositional fallacy is the so-called horn dilemma, which is frequently analyzed in its interrogative form as the fallacy of many questions (see Moldovan 2022 for a review and analysis). The horned man dilemma represents the first presuppositional puzzle, which is commonly attributed to the mid-fourth century BC philosopher Eubulides (Walton 2006, 204). The puzzle reads as follows:

What you have not lost you still have.

But you have not lost horns.

Therefore, you still have horns.

In this case, the presupposition trigger “to lose” has as a satisfaction condition the previous possession of the semantic argument, namely the object that is lost. The problem of this syllogism is the Minor premise. The interlocutor has two possibilities: either to accept that he has not lost horns and thus acknowledge that he has horns, or to deny it, thus admitting that he has lost the horns he had. The only possibility for avoiding the commitment to the possession of the horns is to cancel the presupposition. As seen above, presuppositions can be cancelled through a specific use of negation (the “metalinguistic” or “focal” negation). However, the possibility of cancellation faces an interpretative problem: the default negation, namely the most prototypical and thus heuristic way of interpreting a negative sentence (Jaszczolt 2005; Macagno 2017), is the choice negation (paraphrased as “what you have not lost is your horns”), not the metalinguistic one (“the fact that I have lost horns is false”) (Atlas 2008, 31–32).

This argument is very closely related to the quaternio terminorum, or fallacy of equivocation (Whately 1867, 119; Hamblin 1970; Macagno 2011). The interlocutor can accept the Minor interpreting it as wholly within the scope of the negation (metalinguistic negation). In this way, the conclusion “you still have horns” cannot be drawn. However, the speaker can (and normally does) interpret the statement as a choice negation, triggering the presupposition and thus inferring the conclusion. The ambiguity can be represented as follows:

Hearer

Speaker

1. What you have not lost you still have

1′. What you have not lost you still have

2. You have not lost horns (it is false that “you have not lost horns”)

2′. It is false that you have lost horns

3. You had no horns to lose

3′. You had horns

4. You have no horns (from 1 and 2; from 3 a fortiori)

4′. You still have horns

In the representation of the Hearer’s reasoning, the use of the metalinguistic negation is justified or explained by 3, namely the absence of horns to lose. However, in the Speaker’s reasoning, the choice negation is the default interpretation, which leads to the presupposition 3’ that justifies the conclusion.

The horned man dilemma was explained in the Medieval tradition in terms of defeasible inferences interpreted as necessary ones. The propositions that included what we call nowadays “presupposition triggers,” namely terms such as “to stop,” “to begin,” or “only” (Horn 2011), were called exponibilia (William of Sherwood, Treatise on Syncategorematic words, 16, 3), namely interpretable propositions. They were analyzed as resulting in two distinct conjuncts, which correspond to what it is referred to in modern linguistic theories as the “asserted” and the “presupposed” contents (Ducrot 1972a).

On this view, the horned man paradox was based on an “interpretable” minor premise, which was expounded in two distinct propositions constituting its meaning: a. you have horns; and b. you do not have horns anymore. The problem lies in its negation, as “You have not lost horns” was regarded to imply only defeasibly the affirmation of a and the negation of b, as the cause of its falsity was not specified. As Burton-Roberts puts it (1999, 353), “the speaker who asserts Not-A neither logically affirms nor logically denies the presuppositions of A;” however, unless the presupposition is explicitly denied, a default inference is drawn that the presupposed content is accepted. Thus, the horned man dilemma was a dilemma exactly because the interlocutor could not provide the full explanation of his negation (Walton 1999).

The interrogative variant of the paradox, referred to as the fallacy of “many questions” or “loaded questions,” involves a similar mechanism, which can be analyzed in two distinct dimensions. From a dialectical perspective, the question “Have you lost your horns?” is analyzed as a conjunction of two questions, namely (a) Have you had horns? and (b) Do not you longer have horns? (Walton 1981; Aristotle, De Sophisticis Elenchis 181 b1). In a context in which the first question was not established yet, or its positive reply cannot be considered as part of the interlocutors’ commitment store, the second question cannot be asked, as this would alter the dialectical order (Hamblin 1970, 267) and thus be “risky” (Hamblin 1970, 218; Woods and Walton 1989, 234). At a dialectical level, the loaded question attempts to introduce a commitment into the hearer’s commitment store, which needs to be retracted by rejecting or ignoring the question (Hickey 1993; Ilie 2022).

This alteration of the dialectical order of the questions is combined with a dialogical limitation of the possibility of explaining the negative reply. Like in the affirmative paradox, a fundamental aspect of the deceit resulting from loaded questions is the context of dialogue. In some dialogical activities, the interlocutor is forced to provide an answer within a paradigm that does not include the rejection of the presupposition. As Walton observed (1981, 311), this fallacy works in contexts in which a “loaded” question needs to be interpreted as allowing only two possible answers, ‘yes’ or ‘no,’ such as in an examination or interrogation context (Hickey 1993). As Walton put it (1981, 304):

[The fallacy of many questions] forces the intended victim to accept the unwelcome presupposition no matter which way he answers yes or no. Like the well-known frustrating questions of objective tests, it requires but does not contain an alternative ‘None of the above.’ There is more to the fallacy than its being really loaded while demurely offering the appearance of safety. Not only is it loaded, but all the chambers are loaded.

Especially in these specific dialogical games, the interlocutors’ denial of the presupposed contents is more complex than a simple negative answer. They need to stop the dialogue, reject the question, provide a reason why it cannot be accepted, and in some circumstances even justify why the presupposition is not acceptable. This would place an unjustified burden of disproof on them. The dialogical dimension thus accounts for the dialectical effects of placing an unestablished and more importantly unwelcome commitment in the interlocutor’s commitment store and shifting (and increasing) the burden of proof (Woods and Walton 1989, 234).

6.2 False Dichotomy

The horn dilemma is strictly related to another fallacy, called “false dichotomy,” “black or white” fallacy, or “false dilemma.” This manipulative move involves the forced choice between two alternatives that are not contradictory, and thus not necessarily exclusive. A clear example is the following statement by Salvini concerning the former mayor of Naples, De MagistrisFootnote 6:

Example 2

De Magistris should care about social housing for the Neapolitans instead of inviting all the immigrants of the world and attacking Salvini.

Here, the speaker (Salvini) is presenting De Magistris’ policy favorable to migrants as in contrast with social housing policies. He takes for granted an alternative set composed of only two options (Abusch 2010): either supporting social housing for the citizens, or hosting (or simply not rejecting) migrants. This presupposition, triggered by the replacing additive instead (Zeevat 2004), was not shared by Italian citizens and in particular by Neapolitans. From the point of view of the dialectical approach to presupposition defended above, the “false dilemma” presented as commonly accepted a presupposition that was not part of the interlocutors’ commitments in the given context. In lack of contrary evidence or conflicting commitments, this move provides a prima facie reason to accept the unwarranted unstated assumption.

False dilemmas can be used also in questions: the speaker proposes a choice between two alternatives that are not, however, the only options (Govier 2007). An example is the following messageFootnote 7:

Example 3

#taxpeace, for the ones who filed their income tax statement. Our country gets the money that otherwise it would not get, and the entrepreneurs can go back to work. The alternative? Not doing anything.

Here Salvini intends to propose a choice between a) amnesty for people evading taxes in exchange for a fine and (b) no action—which is presented as equivalent to the Country’s failure to collect any money at all. This proposal (do you want amnesty or nothing?) is grounded on a problematic presupposed disjunction of the possible answers (Levinson 1983, 184), in which the possibility of prosecuting tax evaders (and collecting the whole evaded amounts instead of a symbolic fine) is not mentioned.

The fallacy of false dichotomy is related to loaded questions (Walton 1988, 201–203), as in both cases the question (or the dichotomic statement) rests on a presupposition that is not part of the interlocutor’s commitments (Woods and Walton 1989, 236). However, while in the first case the alternative set may be safe, as the disjunction of the possible answers is a tautology (Hamblin 1970, 218), false dichotomy introduces a choice between a disjunction of alternatives that is not a commitment of the hearer (Walton 1981, 303; Walton 1991b, 343). The dialectical effect of this move was clearly described by Hamblin as follows (1970, 267):

‘Question S, T, . . ., X ?’ places the statement S v T v … v X in the speaker’s store unless it is already there, and in the hearer’s store unless he replies with ‘Statement—(S v T v … v X)’ or ‘No commitment S v T v ... v X’.

The strategies underlying a false dichotomy can be different. Govier (2007)

described the following ways in which a dichotomy can be fallacious:

  1. i.

    Providing a non-exhaustive disjunction (a middle exists).

  2. ii.

    Providing a non-exclusive disjunction (things can be both ways).

  3. iii.

    Providing a non-exhaustive and non-exclusive disjunction.

  4. iv.

    Providing an unclear disjunction, without clarifying the definition of the disjuncts.

  5. v.

    Providing alternatives that do not capture all the items.

  6. vi.

    The situation is indeterminate and thus cannot be classified according to the disjunction.

Example 2 can be interpreted as an instance of the second scenario: Salvini presents De Magistris’ decision as the choice of not developing social housing policies to use the available funds (efforts, etc.) for hosting migrants. This dichotomic choice attributed to the then mayor of Naples was not warranted, and actually in conflict with the available evidence that shows that he tried to pursue both objectives through distinct actions and fundings.Footnote 8 Example 3 is instead a combination of the first and fifth scenario, as the two alternatives (amnesty vs. no action) are not exhaustive, and they fail to capture all the cases (such as evaders who did not file the income tax statement, or the ones that filed it in other countries). A more complex case is the following, in which a complex situation is simplified (sixth scenario) and reduced to an undefined alternative (fourth scenario)Footnote 9:

Example 4

Someone is claiming that the number of ILLEGAL IMMIGRANTS will increase by passing the Salvini decree?? Human protection is granted ONLY to the ones who TRULY deserve it; until now there was a business going on, which made someone rich.

Here, a dichotomy is advanced between immigrants who deserve protection and the ones that do not. The problem lies in using the undefined criterion of “truly (and falsely) deserving” to classify the phenomenon of migration, whose causes are extremely complex (and should be assessed, pursuant to the international law, on a case-by-case basisFootnote 10). Moreover, Salvini opposes the immigrants “truly” deserving protection to the ones taken to Italy by “a business”—expression that Salvini used to refer to a broad category of individuals who were trafficking, transporting, or even rescuing migrants (including refugees and asylum seekers).

6.3 Question-Begging Epithets

Question-begging epithets or appellatives was described by Bentham as a manipulative strategy consisting in the unwarranted use of eulogistic or dislogistic terms (Bentham The Book of Fallacies, chaps. IV, 1). According to this account, this fallacy consists in taking for granted the truth of a controversial value judgment, which would be otherwise needed to be proved, to support a further value judgment or conclusion. In this sense, the use of these terms begs the judgment that had to be proved (Bentham The Book of Fallacies, 216):

The person, act, or thing in question is or deserves to be, or is and deserves to be, an object of general approbation; or the person, act, or thing in question is or deserves to be, or is and deserves to be, an object of general disapprobation. The proposition thus asserted, is commonly a proposition that requires to be proved. But in the case where the use of the term thus employed is fallacious, the proposition is one that is not true, and cannot be proved: and where the person by whom the fallacy is employed is conscious of its deceptive tendency, the object in the employment thus given to the appellative is, by means of the artifice, to cause that to be taken for true which is not so.

This fallacy does not consist merely in attributing a loaded term to a subject (“This doctrine is heresy; therefore it should be condemned”), as there is nothing inherently wrong with advancing a value judgment through the use of loaded language, even if the claim has not been proved (Walton 1991a, chap. 7). The premise is not taken to be true, but simply stated. For this reason, the only risk would be grounding the argument on a weak premise. The problem arises when the truth of this attribution is taken for granted, such as in the following post by Salvini (emphasis added)Footnote 11:

Example 5

Here we are again. This is yet again a shame, worthy of this incapable and harmful European Union. In Brussels they are too busy writing little letters against Italy to take care of these problems.

In this post, Salvini refers to a specific situation in which a Maltese rescued boat allegedly “abandoned” a dinghy with up to 200 migrants on board and redirected them to Italy as a “yet again a shame,” attributing implicitly its responsibility to the European Union that is then described by two epithets (“incapable” and “harmful”). Salvini intends to defend implicitly the conclusion that the EU is mismanaging the migration crisis through the use of generalized characterizations (the redirection of the migrants has happened several times before and is a shame; the EU is useless and harmful) taken for granted through the use of a non-restrictive relative clause (Levinson 1983, 183–184). Such presuppositions at the same time are not based on evidence and beg the point at stake, as they trigger the value judgment that Salvini intends to defend. From a dialectical perspective, this manipulative use of presuppositions relies on the presumption that the speaker has good reasons for taking for granted a given qualification, which in this case is reinforced by Salvini’s institutional office (ministers are presumed to inform citizens). For this reason, it counts as an attempt to include the controversial presuppositions into the interlocutors’ commitment stores, which can be successful when the hearers do not have reasons for rejecting them (Walton 1991b, 350).

6.4 Persuasive Definition

In Example 4 above, Salvini used a particular strategy when he claimed that “Human protection is granted ONLY to the ones who TRULY deserve it.” He performed a twofold move: he redefined a concept, but instead of providing the new definition and defending it with arguments, he merely indicates that there is a true and false meaning of “to deserve protection.” Thus, the term is redefined, but only implicitly, leaving the interlocutors without any possibility of rejecting it. This fallacious move has been normally referred to in the literature as “persuasive definition:” some terms, normally triggering evaluative conclusions, are implicitly redefined, so that they can be used in a way that serves the goals of the speaker (Stevenson 1944; Walton 2001; Macagno and Walton 2010; Macagno and Walton 2014; Pruś and Aberdein 2022). The implicit redefinition is normally signaled by the dissociation markers (Van Rees 2009), such as “true,” “real,” or “actual” (Halldén 1960). An example of its use is the following messageFootnote 12:

Example 6

What a wonderful model of “integration” proposed by our left wing: welcoming without any limits hundreds of thousands of fake refugees with lots of demands! With the #SalviniDecree, the doors are open only for the true refugees; ZERO TOLERANCE for illegal immigrants, agreements with all their home countries and REPATRIATIONS.

Salvini here attacks the alleged left-wing definition of integration in two distinct ways: first, he marks it with scare quotes to indicate that it is a false or unacceptable definition; second, he grounds his reported definition on the notion of fake refugee, which is left undefined. By introducing this new concept, Salvini uses the dichotomy between true and false refugee but leaves the definition of both terms unstated and thus unwarranted. In particular, his policy aimed at denying permits of stay to migrants fleeing their country for “humanitarian reasons,” abrogating the previous law. The “fake refugee” is, according to this perspective, a migrant classified or classifiable as an asylum seeker for humanitarian reasons, but not according to the new standards that Salvini introduced, partially begging the question (why is the old definition of refugee worse/less compliant with international laws than the new one?).

This strategy is particularly effective because of the general lack of knowledge concerning the concepts of migrants and refugees, even though are both commonly used in everyday communication and news reports. As Whately pointed out, definitions are especially necessary in two circumstances: (a) when technical or unfamiliar terms are introduced in the discussion; and (b) when familiar, but potentially ambiguous words, are used with a meaning that is not shared (Whately 1867, 126–127). The omission of a definition has different effects in the two cases. In the former, the hearer has no previous dark-side commitments concerning the meaning of the term and retrieves it from the way it is used or by asking the speaker to define it. In the latter case, however, the omission of a new or unusual definition of a common term can lead to equivocation or a conclusion that is not the debated one (Whately 1867, 143). As Whately put it (1867, 127):

[…] two persons might, in discussing the question whether Augustus was a GREAT man, have some such difference in their acceptation of the epithet “great,” as would be non-essential to that question ; e.g., one of them might understand by it nothing more than eminent intellectual and moral qualities while the other might conceive it to imply the performance of splendid actions; […] but if one (and not the other) of the parties understood the epithet “great” to imply pure patriotism, – GENEROSITY of character, &c., then there would be a disagreement as to the application of the Term, even between those who might think alike of Augustus’s character, as wanting in those qualities.

Similarly, the “fake” refugee can be interpreted by an ordinary reader as an illegal immigrant—and not as migrant who could be classified as an asylum seeker according to the previous (and international) criteria for specific humanitarian reasons. Through this persuasive definition, Salvini introduces a pseudo-agreement (Naess 1966, 92–93), leading the interlocutors to having the illusion of discussing on the same matter.

6.5 Post hoc

The fallacy of post hoc ergo propter hoc (Woods and Walton 1977) consists in drawing a conclusion from an unacceptable causal generalization, or a causal generalization from two events not causally related. Whately analyzed this move as a fallacy of “undue assumption” (Whately 1867, 134), as its deceptive nature lies in suppressing a premise (or conclusion) that is considered as false. The fallacy has three variants:

  1. A.

    Assuming an unacceptable causal relation to predict an effect. Example: This man has been cruel; therefore, he is going to suffer some heavy pains or come to an untimely end. Presupposed causal relation: If someone misbehaves, he will be punished through temporal sufferings.

  2. B.

    Assuming an unacceptable causal relation to establish a cause of an event. Example: This man has suffered many temporal calamities; therefore, he must have sinned a lot.

  3. C.

    Inferring a causal relation from two otherwise unconnected events. Example: This man has been overtaken by a hailstorm. It is because he did not go to mass yesterday. Presupposed causal relation: Not going to mass results in temporal calamities.

The three cases are based on presupposed causal generalizations (Rescher 1961; van Eemeren and Grootendorst 1982) that are not commonly accepted (at least outside specific religious groups). From these unstated premises, different types of conclusions are drawn through distinct patterns of reasoning: from cause to effect in A, from sign in B, and from best explanation in C (Walton et al. 2008, chap. 5). In the last case, the presupposed generalization is used to draw the specific explanation of the co-occurrence of the two events.

This strategy is frequently used in the so-called “conspiracy” theories, consisting in explaining relationships between events through unproven and unacceptable causal generalizations. An example is the following explanation used by Salvini for justifying the selloff of Italian bonds, resulting in a widening “spread” (gap) between Italian and German bond yields (a measure used for assessing the pressure on a country’s bond market in the EU)Footnote 13:

Example 7

The shifts of the so-called “spread” do not correspond to the real life and economy of the Country. In 5 months, we have achieved a lot, and we have a lot of support; I fear that some market manipulator is trying very hard to hinder us.

In this message, Salvini relies on the aforementioned persuasive definition of “real” life and economy, which are left undefined, to suggest the conclusion that the cause of the rising spread is to be found in some international financial conspiracy against the government. This type of post-hoc of type B is grounded on the causal generalizations that market manipulation causes the increase of the spread, and that spread increase causes troubles to the government. The first generalization is similar to a generalization that is commonly accepted, namely that short sales can manipulate stock prices, which can be used for abducing the reason of a stock price fall. However, government bonds are hardly subject to these dynamics. Moreover, in this message Salvini relies on another post hoc of type A: “achieving a lot” is presented as a cause of the financial and economic stability of a country (resulting in turn in the alleged “lot” of support), which would warrant his prediction is that investors’ confidence in Italy should be high and the spread lower.

The last type of post hoc is commonly used in politics for attributing to the speakers merits for events only partially dependent on their actions. An example is the followingFootnote 14:

Example 8

HAVING REDUCED the number of sea arrivals by almost 100 thousand units, and decreased very sharply the number of deaths, is for me great source of pride.

The decrease in number of migrants co-occurred with Salvini’s first months of office as the minister for the internal affairs. Even if people normally accept that anti-immigration policies or agreements with the countries from which migrants come from cause the decrease in immigration, the generalization that the government is always and immediately the cause of migratory fluxes can be hardly considered as reasonable.

The manipulative effect of the post hoc fallacy resides in the similarity of the presupposed generalization with the commonly accepted one (Woods and Walton 1977) and the implicit nature of the causal premise. By leaving it unexpressed, the speaker allows the interlocutors to reconstruct it in the way they consider more reasonable, and more importantly can interpret it in a strategic way in case of attack. In Example 7, Salvini can easily argue that he never intended to claim that speculation caused the spread increase but only suggest that it can be one of the many causes. In Example 8 he can interpret his own claim by stating that he never considered himself as a cause of the decrease of migrants, but merely a contributor. In this sense, the presupposed generalizations are “polyinterpretable” (van Eemeren and Grootendorst 1983, 223).

6.6 Implicitness and Fallacies

As pointed out in the analysis of the aforementioned fallacies, presuppositions play a twofold role in manipulation. On the one hand, they reverse and increase the burden of proof. On the other hand, some presuppositions leave the speaker the possibility of correcting or even rejecting the presupposed content that is contested by the hearer. Clear cases are the persuasive definition and the post hoc, which allow the speakers to provide a different interpretation of what they actually took for granted.

The different degrees of retractability of presuppositions can be explained by distinguishing implicitness from backgrounding. Presuppositions are instruments for backgrounding, but they are not necessarily implicit. As Black put it (1962, 62), referring to presuppositional implications:

To the extent, however, that the speaker uses formal linguistic signals of implications, he forfeits the option of disclaiming the implication. He cannot say, “In saying ‘After the performance was over . . .’ I did not mean to imply that there had been a performance.” He had no choice but to imply it: his words implied it, whether he so intended or not. Now in proportion as the implication is fixed by conventional rules, the differences between implication and formally stated communication may come to seem less important. Attempts to reject the implication by explicit denial can now hardly be distinguished from flat logical contradiction.

Presuppositions are thus constrained by linguistic indicators, which leave different degrees of interpretative freedom to the interlocutors. For this reason, it is possible to classify the aforementioned fallacies according to the type of presupposition and its degree of implicitness. While the fallacies of question begging epithets, false dichotomy, and many questions are based on presuppositions strongly constrained by triggers, in the post hoc fallacy the presupposed causal relation is only indicated and weakly constrained. The interlocutors can reconstruct it in different ways, and in a more generalized or specific way. Finally, the persuasive definition consists in taking for granted a definition, but both the content and the nature of the definition are not constrained. The different degrees of implicitness of the presuppositional fallacies can be represented  in the following diagram (Fig. 2).

Fig. 2
figure 2

Degrees of implicitness in presuppositional fallacies

Full size image

In this figure, the types of presuppositional fallacies are classified according to their generic strategy (false dichotomy; question-begging) and ordered according to their degree of presuppositional implicitness (ranging from the more explicit ones to the more implicit ones, at the bottom of the figure). Depending on the degrees of implicitness of the presupposed contents, the speaker’s burden of retraction and the hearer’s burden of rejection can change. While in case of constrained presuppositions the hearers need only to provide reasons for rebutting the unwanted dark side commitment, which can hardly retracted by the speaker, when implicit presuppositions are used, they may need also to provide reasons in support of their interpretation or face the accusation of misunderstanding.

7 Presuppositional Strategies in Fallacies: The Case of Straw Man

The aforementioned fallacies are grounded on problematic presuppositions. Their deceptive nature lies in a commitment that is not accepted or acceptable but is taken for granted as already part of the interlocutors’ commitment store. However, presuppositions can also play an important role in other fallacies. A crucial case is the straw man (Macagno and Walton 2017), which consists in an attack against the distorted report of the opponent’s viewpoint (Capone 2016). The other’s position can be simply stated and then attacked. But the speaker can also take for granted the reported distorted position instead of asserting it, to present the manipulated commitment as already granted. This strategy can be illustrated by the following messageFootnote 15:

Example 9

Where is it written that I have to take 4 billion Euros from the Italians’ pockets because an EU commissioner told me to do so???

Through this rhetorical question, Salvini reports indirectly the altered version of the EU commissioner’s statement. The commissioner underscored that Italy had to comply with the obligations undertaken, and in particular the reduction of the country’s deficit. Salvini distorts the claim, presenting it as the personal opinion of the commissioner about a withdrawal of money from the Italians, and not the avoidance of specific spendings. Through a bound sentence (phrase liée, see Ducrot 1972a, 118–127; Martin 1973), Salvini presupposes that the commissioner told him to take 4 billion Euros from the Italians. In this fashion, the distortion becomes harder to detect and rebut by the interlocutors. A similar strategy is used in the following exampleFootnote 16:

Example 10

The Italians pay the salary to the European Bureaucrats—they are not «beggars» or «rug sellers»! Stop with your insults, RESPECT for the Italians!

Here, Salvini attacks Moscovici (an EU commissioner) by distorting his statement, attributing to the latter the claim that Italians were beggars and rug sellers, and taking for granted that he did it to insult Italians. Moscovici originally stated that “we cannot engage in a rug-sellers like negotiation.” Salvini manipulates this viewpoint in two distinct fashions. First, he denies polemically (Ducrot 1984, 217; Moeschler 1992) the content of two mixed quotations, namely “beggars,” which was never used by Moscovici, and “rug sellers,” which was used metaphorically to describe negatively Salvini’s negotiation style. The use of mixed quotations is an instrument for presupposing metalinguistically that someone (in this case Moscovici) uttered these words when was referring to the Italians (Maier 2014). Then, through the use of the change of state verb to stop (Levinson 1983, 181), Salvini presupposes that Moscovici’s claim amounts not to a meta-discursive comment (the negotiations are rug-sellers like), but merely to insults against Italian, altering illegitimately its dialogical purpose (which is now turned into a quarrel). Through these two presuppositional strategies, the misrepresentation and undue reinterpretation of the original statement are taken for granted and presented as accepted and shared commitments.

8 Conclusion

Presupposition is an essential dimension of human communication. Through the use of semantic, syntactic, and pragmatic triggers, some contents can be backgrounded. However, what do these backgrounded contents amount to in a dialogue? What is their function? This paper attempted to provide an analysis of presupposition from a dialectical perspective, showing how it can be conceived as the introduction of (new or old) dark side commitments in the participants’ commitment sets. This dialectical move can be explained through a twofold inference. From the hearer’s side, presuppositions are inferred as explanations of the speaker’s linguistic behavior. From the speaker’s side, a presupposition is grounded on a predictive presumptive reasoning, aimed at supporting the conclusion that the content taken for granted is accepted by or acceptable for the interlocutor. This twofold inference allows the assessment of the use of presuppositions in terms of reasonableness. On this view, a presupposition is not only evaluable as accommodable or not; it can be also grounded on accepted, unaccepted, or unacceptable premises, and thus have different degrees of reasonableness.

From a dialectical perspective, the introduction of a dark side commitment based on presumptive reasoning amounts to an attempt to reverse and increase the burden of proof. The interlocutor has to rebut (cancel) a commitment s/he never accepted, and to do so the dialogue needs to be interrupted through a meta-dialogical move and in some contexts of dialogue, reasons need to be advanced. This feature makes presuppositions the basis of several manipulative strategies. In particular, five fallacies have been shown to be grounded on manipulated commitments: (a) the fallacy of false dichotomy (in its interrogative form known as black of white questions) involves the presupposition of an unacceptable paradigm of choices or answers; (b) the fallacies of many questions and (c) question-begging epithets are based on the presupposition of unaccepted propositions or qualifications; (d) the manipulative use of persuasive definition consists in presupposing a redefinition of an emotive term; finally, (e) the post hoc is grounded on the presupposition of an unacceptable causal relationship. Moreover, presuppositions can be used in other fallacies, such as the straw man fallacy, to increase the burden of rejecting a distorted reported speech and make it more difficult to detect.

This paper attempted to show how the phenomenon of presupposition, one of the most debated and controversial in the fields of linguistics, pragmatics, and philosophy, is indeed crucial for argumentation studies, which can offer instruments for its qualitative and quantitative analysis. The pervasiveness of the manipulative uses of presupposition can be clearly understood by considering the distribution of fallacies and arguments within the corpus from which the nine examples used in this paper are taken. More than 50% of the arguments used by Salvini in his tweets posted in the 180 days from the date on which he took office as minister for Internal Affairs are affected by presuppositional fallacies (not including the straw man) (Macagno 2022a, b). Understanding the different ways in which presuppositions can be used to manipulate messages, discourses, and dialogues can raise awareness of their importance in argumentation and constitute an instrument for contrasting their effects in communication.