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A Relevance-Theoretic Account of the Evolutionof Implicit Communication

Anne Reboul
Laboratory on Language, the Brain and Cognition (L2C2, CNRS FRE3406),
University Claude Bernard-Lyon 1
Implicit communication is the single feature of human linguistic communication absent from any otheranimal communication system. The recent argumentative theory of reasoning, which links the evolution of reasoning abilities in humankind to the evolution of linguistic communication suggests that linguistic communication evolved to allow humans to manipulate each other, and that communicating
things implicitly allowed them to hide their manipulative intentions. Manipulation in that sense iscompatible with Gricean cooperation.
Keywords:

1.

implicit communication, Gricean cooperation, manipulation, intention, argumentation

Introduction

The question of the evolution of language, after having provoked a great deal ofinterest in the eighteenth and nineteenth centuries, underwent a long decline during thelate nineteenth and most of the twentieth century, before being revived by Pinker andBloom in 1990. This triggered a vast number of papers and books (see Bickerton 1996,
Deacon 1997, Dunbar 1996, 2004, Fitch 2010, Hauser 1996, Jackendoff 2003, Mithen
2006, Knight, Studert-Kennedy and Hurford 2000, Tomasello 1999, 2008, 2009, Reboul
2007, to mention only a few books), most of which have quoted Hockett's (1963) classical list of thirteen "essential features of language, which make it unique among animalcommunication systems:• Language uses the vocal auditory channel, with three consequences which arealso listed by Hockett among his thirteen essential features: broadcast transmission (the utterance can be perceived not only by the addressee, but by everyonein the vicinity), rapid fading and total feedback (speakers hear what they say);• Language has interchangeability (the speaker can become the hearer and viceversa);• Language has specialization (it implies specific encoding-decoding processes);• Language has semanticity (utterances are meaningful);• Language has arbitrariness (linguistic meaning is not generally based on iconic
links between morphemes and their referents);

2• Language has discreteness (utterances differ in their parts, not as wholes);• Language has displacement (it is possible to speak of absent or even of non-existent objects);• Language has productivity (or generativity: there is no limit in principle to thenumber of sentences, which can be produced in a given language);• Language has duality of patterning (at the phonological level, yielding morphemes, and at the syntactic level, yielding sentences);• Language is traditionally transmitted (regardless of whether or not there is a biologically based language system, specific languages have to be learnt).
It seems, however, that Hockett missed an important feature of language: implicit com-munication. 1
What is more, it should be noted that, though the whole set of features listed by
Hockett is indeed specific to human language and not to be found in any other known
animal communication system, this is not the case for each feature taken in isolation.
Indeed, all of them seem to be found in one species or another (see Fitch 2010). But
the core feature of human linguistic communication that was absent from Hockett's list,
i.e., implicit communication, is unique in the sense that, as far as is now known, no animal communication system manifests implicit communication. The very fact that implicit communication is the unique feature that is specific to human linguistic communication should make it central to any account of linguistic evolution in that it does notseem to have evolved from anything else. 2 However, despite its uniqueness, it is nevermentioned. It is my aim in the present paper to remedy that omission and to propose
some tentative ideas as to why language (and only language) allows implicit communication.
The paper is organized as follows: I begin (in §2) by showing that a Neo-Gricean
scenario for the evolution of implicit communication is implausible, given that implicit
communication is far from automatic. I then remind the reader of the original Gricean

Implicit communicatio n occurs whenever what is communicated in an utterance is different fromwhat is said (in the standard Gricean sense).
2 Evolution is here to be understood in the neo-Darwinian way of a feature occurring due either tothe fact that it offers an adaptive advantage (the individuals with the feature will leave more offspringthan those without it) or through genetic drift (where it is neutral). In the first case, the feature may
have been selected for itself or may be a byproduct of another feature which itself is an adaptation(so-called exaptation). My goal here is not to give a complete account of the evolution of implicit
communication, but rather to indicate why implicit communication is advantageous, hence can beadaptive, whether it is an exaptation or an adaptation. One reviewer remarked that it is inferential
communicatio n in general (i.e., content accessed through inferences) rather than implicit communication (in the sense of note 1) that is specific to language. This is right, but in keeping with the remarks
above, I take it that the evolution of implicit communication could precisely be parasitic on the pre1

existing human abilities for using inferences in communication.

A Relevance-Theoretic Account of the Evolution of Implicit Communication

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definition of non-natural meaning, which leads directly to the principle of cooperation
for the recovery of speaker's meaning (§3). I introduce the argumentative theory ofreasoning (§4) arguing that it presupposes a coevolution between language and reasoning abilities and that it opens the door to the possibility that language evolved for manipulative rather than purely cooperative reasons. In §5, I defend manipulative accounts
against some objections, relying on Krebs and Dawkins' (1984) classical paper. I thenoutline a manipulative scenario for the evolution of implicit communication (§6), before
discussing further reasons to link argumentation and manipulation (§7). Finally (§8), I
outline a multi-layered account of collaboration, argumentation, manipulation and cooperation.

2.

Is a minimax account possible?

Minimax accounts are basically economic principles to the effect that cost should
be minimized, while benefits should be maximized. As Hom (2004) pointed out, minimax accounts, though usually not presented in such terms, are frequent in semantics
and pragmatics:• classical rhetorical recommendations (from Aristotle's Rhetorics on) encourage
speakers or writers to be as concise and clear as possible;• Post-Gricean accounts, such as Relevance Theory (Sperber and Wilson 1995), areclearly also instances of minimax; and• Neo-Gricean accounts, such as Hom's and Levinson's (2000), are other instances.
There is, however, a major difference between Post-Gricean accounts and Neo-Gricean
accounts: clearly the Relevance Principle concerns the costs and benefits for the hearer,
while Neo-Gricean accounts aim at balancing costs and benefits for both the speaker
and the hearer. I will concentrate here on Hom's account, because he explicitly articulates it in minimax terms. Hom's account concerns Generalized Conversational Implicatures.
Grice (1989) distinguished between conventional implicatures, which are part ofthe conventional meaning of the utterance and cannot be cancelled without contradiction, and conversational implicatures, which are not part of the conventional meaning of
the utterance, and are thus cancellable. However, as Grice himself recognized, someconversational implicatures have a conventional component in the sense that they seemtriggered by lexical items, though they are nevertheless cancellable. He called these
Generalized Conversational Implicatures.
Hom's minimax account (Hom 2004: 13) is based on the Q- and R-principles(which are not among theGricean maxims):

4• Q-principle: say as much as you can modulo Quality3 and R;• R-principle: say no more than you must, modulo Q.
The Q-principle concerns the hearer and is a lower-bounding guarantee of sufficiency of
informative content, while the R-principle concerns the speaker and is an upper-bounding correlate of the law of Least Effort, enjoining minimization of form. Thus, Horn insists on form as well as content in the generation of implicit meaning. This is especially clear in his discussion of categorical sentences (Horn 2004: 11):4
All/Every F is G.
E: No F is G.
1: Some F is G.
0: Not every F is G (Some F is not G).
A:

As is well-known, A implies I and 0 is the denial of A (it contradicts A); as well, I implicates 0. On Horn's account, it is because the "basic forms" (i.e., AlE) are both more
informative and briefer than I/0 that I implicates 0. I will not discuss Horn's accountas such (but see Noveck and Sperber 2007, Reboul 2004), but will rather discuss thepossibility of giving a Neo-Gricean minimax account of the emergence of implicit communication along the following lines:
Satisfying both Q- and R-principles will necessarily lead to the emergence of
implicit communication as a result of the pressure for making profitable communication.
In other words, implicit communication exists as a result of the pressure for conveying
as much content as possible from as parsimonious as possible a linguistic form.
There would be several problems with this proposal, the first and least important of
which being that it would only account for a small part of implicit communication, i.e.,
Generalized Conversational Implicatures. It is indeed hard to see how it could accountfor presuppositions, or particularized conversational implicatures, though it might be argued that it could account for conventional implicatures (through a grammaticalization
process). There is however another and more important problem: 5 Neo-Gricean accounts in general, and Horn's in particular, seem to reduce all the cost on the hearerside to the cost of processing the linguistic form, but it is not clear that this is a correct
assessment of what happens in implicit communication. Indeed, experimental studies

The Gricean maxim of Quality enjoins sincerity (say what you believe to be true).
Categorical sentences are the sentences found in syllogisms and were identified by Aristotle whoplaced them in his well-known square of oppositions (see Aristotle, On Interpretation §6-7).
5 Indeed, this problem concerns not only a putative Neo-Gricean account of the emergence of implicit communication, but also the existent Neo-Gricean accounts of Generalized Conversational Implicatures.
3

4

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on Generalized Conversational Implicatures6 have shown that they are indeed quite costly to generate (and the implicatures related to categorical sentences have been extensively studied), and this leads to their non-generation in an important proportion of cases, up to 40% (for a review of this experimental work, see Noveck et Sperber 2007, andfor a discussion, see Reboul 2008). Given these data, which have been replicated repeatedly in experimental studies, conveying more content with fewer or shorter words isfar from being ensured despite the Q- and R-principles. But if this is the case, it is notclear that minimax principles can successfully account for the emergence and the (continuing) existence of implicit communication.
By relying on principles such as Q- and R-, Neo-Gricean accounts avoid having
recourse to intentions to account for implicit communication. Given however that thehope of accounting for implicit communication on the basis of a minimax analysis encounters major difficulties, let us now turn to Gricean and Post-Gricean intentional accounts.

3.

Intentional accounts of linguistic communication

In his well-known paper, first published in 1957, "Meaning", Grice (1989: 220) introduced the notion of non-natural meaning (or meaningNN), which he defined as follows:"A meantNN something by x" is roughly equivalent to "A intended the utteranceof x to produce some effect in an audience by means of the recognition of thisintention"
This definition is usually interpreted as implying two intentions, a primary intention to
produce an effect in an audience, and a secondary intention that this effect be producedby the recognition of the primary intention.
Similarly, in Relevance Theory, any (human) act of communication is subtended by
two intentions:
Informative intention: "To make manifest or more manifest to the audience a setof assumptions f' (Sperber & Wilson 1995: 58);
Communicative intention: "To make mutually manifest to audience and communicator that the communicator has this informative intention" (Sperber & Wilson 1995: 60-61).

Thus Gricean and Post-Gricean accounts are not only intentional accounts, but incorporate two embedded intentional levels. This raises the question of why the second em-

6 Most of the experimental work on implicit
communication has concentrated on scalar implicatures, which are the prototype of Generalized Conversational Implicatures.

6

bedded intention (the secondary intention in the Gricean account and the communicative
intention in the Relevance-Theoretic one) is necessary at all.
The answer to that question is that the second intention is necessary to account for
implicit communication (see Reboul & Moeschler 1998). In other words, if linguistic
communication were codic, a single intention (the primary or informative intention)
would be enough. The second intention is there because it plays a role in the recovery
of implicitly communicated content: in the Gricean account, through the recognition of
the first intention; in the Relevance-theoretic one, because it is the justification for theCommunicative Principle of Relevance and the least effort heuristic (see below).
That the second intentional level is not necessary for codic communication can beseen from animal communication, which, as far as is known, is entirely codic, though,in some cases at least, it is intentional, as shown by audience effects. For instance,
alarm calls are not produced automatically when the communicator sees a predator, but
depend (i) on the presence of an audience, and (ii) on the fact that the audience is appropriate (which usually means that it includes kin; see Hauser 1996, Cheney and Seyfarth 1990). In such cases, the communicator has the intention of producing an effectin its audience (on a Gricean account) or has an informative intention (on a Relevancetheoretic one). And, emphatically, the effect on the audience does not depend on its
recognition of the communicator's intention. In other words, success in codic communication does not depend on either the communicator or the audience having a mindreading ability (the ability of attributing intentions to others) (see Reboul 2007).
Second intentions come into play when there is a gap between speaker meaningand sentence meaning. (This is where Searle's (1969) understanding of meaningNN
went astray, when he reformulated the secondary intention and incorporated conventional meaning in it). On the Gricean account, in implicit communication, the second intention (that the effect is produced in the audience by the recognition of the primary in7
tention) is necessary to close the gap between speaker meaning and semantic meaning.
In Relevance Theory, the communicative intention is what puts the ostensive in "ostensive-inferential communication". The fact that linguistic communication is ostensive isthe justification for the Communicative Principle of Relevance:"Every ostensive stimulus conveys a presumption of its own optimal relevance"(Sperber & Wilson 1995: 260).
And the Communicative Principle of Relevance triggers the least effort heuristic, whichis the basic mechanism in pragmatic inferences in Relevance Theory.
Some criticism has been leveled against double accounts of linguistic communication. In one such endeavor, Gliier and Pagin (2003) have argued that double-intentional

Incidentally, this is where the link between the first Grice (the Grice of meaningNN) and the second Grice (the Grice of Logic of conversation) comes in.
7

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accounts of linguistic communication presuppose a sophisticated rnindreading ability
and that, thus, any cases of individuals who are without such abilities but are nevertheless able to communicate would constitute a counter-argument against such theories.
They explicitly targeted Gricean and Post-Gricean accounts, taking as a counter-example
those autistic or Asperger patients who have sufficient linguistic abilities to communicate. Basically, Gliier & Pagin's argument is of the kind known as epiphenomenal arguments in philosophy. 8 They are based on the comparison of the performances of two
populations, one with a given cognitive ability (here mindreading), and one without it,
in a behavior that is supposed to require that ability (here linguistic communication). If
the two populations have identical performances, then it can be claimed that the cognitive ability is, in fact, epiphenomal to the performance of the task. Thus, an epiphenomenal argument can only go through if the two populations are behaviorally indistinguishable in their performance. This, however, is far from being the case for linguistically able autistic and Asperger people. Indeed, their difficulties and peculiarities inlinguistic communication (including major difficulties with implicit communication,from indirect speech acts to conversational implicatures, through sarcasm) are part ofthe continuing major difficulties of autistic and Asperger people in social relationships
throughout life (for the complete argument against Gliier and Pagin, see Reboul 2006).
Thus, there seems to be rather strong justification for double-intentional accounts,
and, ever since Grice's "Logic of conversation", linguistic communication has been taken to be cooperative, because it is only through cooperation between speaker and hearer(the speaker "tailoring" his utterance to the abilities and knowledge he attributes to thehearer) that the two intentions can be recovered.

4.

Reasoning and the evolution of communication

In a series of papers, Sperber and Mercier (see Mercier 2009, Mercier & Sperberin press) have proposed that human reasoning abilities are mainly social, in that they
have evolved to allow humans to come to collective decisions by persuading one another that a given course of action is best. This supposes two mechanisms: (a) the production of reasons (on the communicator's side), and (b) the checking of proposed reasons(on the addressee's side). Basically, Mercier and Sperber were interested in explaining
why experimental studies have often found human reasoning to be wanting (for a general and accessible review, see Piatelli-Palmarini 1994). Most explanations for these8 Epiphenomenal arguments are especially frequent in philosophyof mind. A paradigmatic example is to be found in Chalmers (1996). Chalmers was arguing against functionalist (or reductive) accounts of qualia and was trying to show that qualia do not play a role in the production of behavior.
Thus qualia would be epiphenomal as far as the production and the interpretation of behavior is concerned.

8

failures in reasoning that have been proposed are in terms of dual processes: the idea isthat humans have two highly different systems for problem-solving: one, an intuitive
system, which is based on heuristics (for a good presentation of heuristics, see Gigerenzer 2007), and which is fast, often phylogenetically determined, unconscious andstrongly domain-specific; the other, an analytic, system that is, by contrast, more in
keeping with logical norms of reasoning, and is conscious, linear and not domain-specific. On most dual accounts, errors in reasoning in the experimental studies are explained by the fact that heuristics were used, while they were inappropriate in the context.9 Some dual account theorists, however, do not charge all errors in reasoning to theheuristic system. For instance, Evans (2007) argues that the reasoning system also
plays a part in the often rather poor human reasoning performances, mostly through satisficing, that is, being content with a good enough rather than an optimal solution.
Mercier and Sperber do not argue against dual accounts of reasoning. Rather, they
concentrate on the so-called analytic system. Based on a detailed analysis of the specific "biases" that have been identified in the reasoning literature, for instance the socalled "egocentric bias" (a preference for one's own beliefs over beliefs communicatedby others), they argue that reasoning indeed did not evolve for general problem solving,
but that it evolved for argumentation. In other words, it is at its best in social contexts
in which a collective decision has to be reached, and in which, more often than not, one
is trying to persuade others of one's own position. This explains why people are often
rather bad at tasks where they are asked to solve a fairly abstract (and usually not very
relevant to them) problem on their own. By contrast, performances are often much improved when subjects are asked to come up with a collective solution to a given problem.
I will take for granted that Mercier and Sperber are right in their account of theevolution of reasoning. What is important here is the implication of their account of
the evolution of reasoning has for the evolution of public languages. Clearly, if reasoning did evolve for argumentation and persuasion, its evolution was intimately linked tothat of public languages. This suggests a co-evolutionary scenario in which the abilities
for public languages coevolved with the abilities for reasoning and fulfill the same function, i.e., argumentation. The hypothesis that public language evolved for argumentation is supported by Brandom (2000, 2009) from the radically different position of philosophical inferentialist pragmatism. 10 Brandom claims that one important support for

The main idea, which is not in dispute, is that heuristics usually work fairly well, but that theylead to dysfunctional answers when they are used out of the type of contexts for which they have
evolved. Given the usually poor ecological design of experimental studies, it is hardly surprising thatheuristics would lead to incorrect answers.
10 Pragmatism should not be confused with pragmatics. Pragmatism is an American philosophicaltrend, which was initiated at the end of the XIXth century under the (rather different) impulses of William James and Charles Sanders Peirce (other well-known names in pragmatism are John Dewey and9A Relevance-Theoretic Account of the Evolution of Implicit Communication

9

this hypothesis is the existence in natural languages of logical connectives. This agrees
rather well with at least parts of Mercier and Sperber's proposal, especially if one extends Brandom's observation beyond logical connectives to pragmatic connectives ingeneral (see below §7).
Thus, in summary, the argumentative theory of reasoning is strongly linked to theevolution of language as a public system of communication dedicated to argumentation.
It thus opens the possibility that, contrary to general opinion, language evolved not
through cooperation, but through manipulation, where manipulation is understood as"actively changing the victim's behaviour" (Krebs & Dawkins 1984, 383).

5.

The viability of manipulative accounts of communication

In 1984, Krebs and Dawkins claimed that the only possible basis for the evolutionof communication (in any species, including human language) was for the manipulationof others, i.e., to control (or at least influence) their behavior. This does seem to agreewith Mercier and Sperber's argumentative theory. However, Mercier and Sperber insist
that they want to maintain a cooperative view of language and its evolution, and thatmanipulative accounts meet with insuperable objections. Additionally, given that thecentrality of implicit communication seems to imply a degree of cooperation (see §3), it
may seem at first glance that the very existence of implicit communication disproves
any manipulative account of linguistic communication. However, I will argue that
Krebs and Dawkins are right and that in fact, there is no real contradiction between cooperation and manipulation.
So let us begin with Mercier and Sperber's argument against Krebs and Dawkins'
manipulative account: "If the fact of receiving information from someone else is usually
damaging for the members of a species, then evolution will quickly make them 'deaf'
to this information. ( ... ) Given that individuals who send signals must find some advantage in so doing, this means that communication, to be evolutionarily stable, must be'honest' in a majority of cases" (Mercier 2009: 16. My translation). This argument,
however, does not seem entirely fair to Krebs and Dawkins. As Mercier (2009) indicates there are two versions of the Krebs and Dawkins' paper (the first was published in1978), and in the second version (1984), the authors noted this problem, and, though
Mercier does not discuss it, propose a solution to it. I will not discuss this solution indetail, but I will briefly outline an answer to Mercier and Sperber's criticism. Krebs
and Dawkins' proposal rests on a distinction between two kinds of manipulations: manipulations that benefit the manipulator, but harm the "victim"; manipulations, which
benefit both the manipulator and the "victim". It should be clear that Mercier's criticism quoted above applies in the first case, but not in the second. Indeed, the second

Richard Rorty).

10case is perfectly compatible with cooperation. ll As said above (see §3), any viable account of human communication has to include intentions. Thus, the distinction proposed by Krebs and Dawkins should be reformulated in intentional terms:• if the communicator intends to produce by his utterance a behavior in his addressee, which (the communicator believes) will benefit himself but will be detrimental to the addressee, then the communicator is engaging in hostile manipulation;• if the communicator intends to produce by the utterance a behavior in his addressee, which (the communicator believes) will benefit himself, and will be either beneficial or neutral to the addressee, then the communicator is engaging in
non-hostile manipulation. 12
It should be clear that non-hostile manipulation is perfectly compatible with coopera-tion. What is more, there is no objection to a manipulation-based evolutionary accountof communication, as long as the manipulation involved is non-hostile. Indeed, I will
now claim that such an account yields a natural explanation for the emergence and continuing existence of implicit communication.

The evolution of implicit communication

6.

I will now defend a general hypothesis regarding the evolution of implicit
communication: 13
Implicit communication evolved to facilitate manipulation by allowing communicators to hide their (manipulative) intentions.

As a matter of fact, Krebs and Dawkins dub the second kind of manipulation "cooperation".
This, however, seems unsatisfactory. Notably, the "cooperation" in question has nothing to do with
Gricean cooperation: though Krebs and Dawkins talk about "mindreading", the activity as describedby them has nothing to do with attributing mental states to others, but merely denotes the prediction ofothers' behavior (in other words, behavior reading). Additionally, Krebs and Dawkins have nothing to
say about implicit communication, while the Gricean cooperative account is clearly dedicated to it.
And finally, as I hope to show, though manipulation may not detrimental to the "victim", this does notmean that no deception is involved.
12 If the communicator, in the second case, is systematically mistaken in believing that the behaviorof the addressee will be either beneficial or neutral to the addressee, then his own reputation will probably suffer and he will probably be much less successful in his later manipulative communication.
This is independent of the hostile or non-hostile intentions of the communicator, just as the sincerityof the (mistaken) speaker who asserts a falsehood means that he follows the Quality maxim (say what
you believe to be true), even though what he says is false.
13 Regarding presuppositions and conversational implicatures: the distinction between these types of
implicit communication is a matter of the evolution of languages, rather than of language.
11

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II

This will become clear from examples. I will briefly present examples of most major
categories of implicit communication, 14 i.e., presupposition, and conversational implicatures (both Generalized and Particularized Implicatures).
Let us begin with Particularized Conversational Implicatures:
(1)

A:
B:
pci:

Do you know where Anne lives?
Somewhere in Burgundy, 15 I believe.
B does not know where exactly Anne lives.

B may know quite well Anne's exact address, but not want A to write to or visit Anne.
By his utterance, B can hide his intention not to give this information to A, or later
deny having had this intention.
In Generalized Conversational Implicatures, we find something rather similar:(2) A:B:
gci:

Has Peter finished his homework?
Well, he has done some of the exercises.
Peter has not done all of his exercises.

Suppose that A is Peter's mother and that B is Peter's older sister. By her utterance, B
implicates that Peter has not done all of his exercises and, hence, that he has not finished his homework and, for instance, should not be allowed to go with her to the pictures. At the same time, B can insist that, in producing that utterance, she did not mean
to prevent Peter from going with her to the pictures.
Let us now tum to our third case of implicit communication, presupposition:
(3)

A:
B:
pp:

I have decided to give the job of manager of the local branch to John.
That's an excellent choice, especially now that he has stopped drinking.
John drank.

B can claim that he has no unfriendly intention toward John and that, indeed, he praised
1\s choice, even though he hopes by his utterance to change A's mind as to the suitability of John for the post.
I would like now to point out a few general points about these types of implicit
communication. First of all, in none of these cases is there any lie stricto sensu. For
instance, in the case of (1), it is true that Anne lives in Burgundy, though not that B
does not know where exactly. In the case of (2), it is true both that Peter has done all
his exercises and that he has done some of them (because all implies some). And in the

14 In each case, the content implicitly communicated is either the implicature or
the presupposition.
And, though there has been debate as to whether generalized conversational implicatures and presuppositions are implicit, it seems clear that they are perfectly in keeping with the definition of implicit
communication given in note 1 above. I leave aside conventional implicatures, which raise different
questions.
15 Burgundy is a region in France.

12case of (3), it is true both that John does not drink (now) and that he used to drink.
Second, in all of these examples, the manipulation need not be hostile to the addressee.
In (1 ), it may be the case that Anne would be nasty to A were they to be in contact andthat B is trying to protect A from the repercussions of such rude behavior. In (2), B
wants to go to the picture with her boyfriend and he cannot stand Peter. B wants tospare her mother's illusion that Peter is universally beloved. In (3), B may be sure that
if John is indeed given the job, he will prove a terrible liability to A's company, andwants to protect A from that danger. Third, though there are neither lies nor hostile
manipulative intentions in these cases, this does not mean that there is no deception.
The deception involved differs from lies in that it does not concern the content that is
explicitly communicated by the utterance. Rather it concerns one intention of the
speaker. However, the intention that the speaker can deny having or being committed
to is neither the primary or secondary intention (in the Gricean account), nor the informative or the communicative intention (in the Relevance-theoretic one). Nevertheless, arguably, in all of the cases examined above, the speaker preserves the possibility
to deny that he or she has a specific intention, though that intention is a further intention: the intention to manipulate the addressee, to lead the addressee to do what the
speaker wants him or her to do. Basically, what this means is that you can have
(Gricean) cooperation within a manipulative wider context.
Let me, as a conclusion to this section, turn back to Mercier's objection to a manipulative account of the evolution of communication, the conclusion of which I reproduce here: "Communication, to be evolutionarily stable, must be 'honest' in a majorityof cases" (my emphasis). The notion of honesty is complicated in two ways. First, it isambiguous between two readings, only the first of which is relevant to Mercier's argument: honesty may be read in an entirely non-psychological (and non-Gricean) way, as
describing the fact that the message has true content; 16 honesty may be read in a psychological (and Gricean) way, as describing the fact that the message has a content
which the communicator believes to be true. A second complication has to do with thescope of honesty: does it concern the content explicitly communicated, does it also include the content implicitly communicated, and finally, does it concern intentions, andif so, which intentions does it concern?
The reverse of honesty is deception and the complications described above related
to the notion of honesty have interesting repercussions regarding deception. First of all,just as there is a non-psychological notion of honesty, there also is a non-psychologicalnotion of deceptionY There is of course a psychological notion of deception (relevant
for human communication) and under that reading, deception implies the intention to16

I will not go into details, but the argument is parallel to that in note 12 above.

17

It is known as functional deception and has been found in non-human primates (see Byrne andWhiten 1988).

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deceive, and, again, the scope of that intention makes a difference as to the nature of
the deception. If the communicator's intention to deceive concerns the explicitly communicated content of his or her utterance, then he or she lies. When it concerns theimplicitly communicated content (but not the explicitly communicated one), no lie is involved. This is what happens in (1) where B is certainly not lying (the content he explicitly communicated is true), but the conversational implicature is false (B does know
Anne's exact address). When the intention to deceive concerns the speaker's intentions(in general), it should be noted that the distinction between non-psychological and psychological readings of honesty and deception vanishes: one cannot be mistaken about
one's own intentions. Obviously, again, no lie is involved. However, a further complication occurs. Given double-intentional accounts of linguistic communication, which as
we have seen are necessary to account for implicit communication, deception concerning primary and secondary intentions (or, equally, concerning informative and communicative intentions) would be self-defeating and indeed appears to be plainly impossible.
Let me quickly outline why this is so: if a speaker intends to lie, he will not haveany chance of success if his intention of lying is recognized by his putative victim. In
other words, lies depend for their success on (a) the fact that the speaker's intention tolie is not recognized by his victim; and on (b) the fact that his primary and secondary
intentions (or, equally, his informative and communicative intentions) are recognized byhis victim. This implies that, in lies, the scope of deception covers both the explicitly
communicated content and the speaker's intention to lie, and it also strongly implies
that the speaker's intention to lie is neither the primary nor the secondary intention 18 (orequally the informative or the communicative intention). The same thing, mutatis
mutandis, applies when deception targets implicitly communicated content. In otherwords, deception regarding such further speaker's intentions will systematically occur
whenever deception exists concerning communicated content (whether this is implicitly
or explicitly communicated).
The further intentions implied by deception regarding communicated content are
however different from the manipulative intentions implied in all of cases (1) to (3), as
we shall now see.

7. Argumentation and manipulation
Mercier (2009, 24) discusses the following example: A wants B to help him attack

18 This was the basis for one major criticism
against Grice's meaningNN' that is, that it cannot accommodate lies. I think that the criticism is misguided: it confuses primary and secondary intentions
with further intentions, which also exist when no lie is made (for a defense of this position, see Reboul 2007). Here the distinction between proximate and ultimate intentions introduced below (see §8)
is indirectly relevant. The criticism against Gricean meaningNN confuses proximate and ultimate intentions: only proximate intentions are involved in meaningNN·

14

a third party, but B is not enthusiastic. Mercier compares two different ways in which A
can try and convince B that the attack is a good idea:
(4)

a.
b.
c.

John has insulted your mother.
Let's go and attack John.
Let's go and attack John because he has insulted your mother.

In his comparison, Mercier is mainly interested in whether B will or will not use reasoning. Basically, in saying (4a-b ), A is giving B a reason (4a) to justify the conclusion (4b). This may trigger a reasoning process in B, evaluating whether (4a) really is agood reason for (4b). However, if A says (4c) (rather than (4a-b)), he decidedly leads B
to use reasoning through the use of the word because. As Mercier notes, using suchlinguistic tools (e.g., thus, then, if ... then, etc.) encourages reasoning of the evaluativekind. In such cases (with different degrees of expliciteness), we have argumentation(and reasoning) without manipulation: A has the intention to convince B to attack John,but this intention is clearly explicit in both (4a-b) and (4c).
However, as Mercier himself recognizes, this is not necessarily the case, notably
because of the so-called egocentric bias. As Mercier notes (2009, 116; my translation):"In the case of beliefs, the mechanisms of coherence checking should not only make usaware of conflicts, it should also promote our own beliefs over communicated beliefs
when they conflict (we can call this an egocentric bias)". As he points out, this affects
inferential mechanisms as well: "When someone tells us something, when we accept it
and make inferences based on this information, the resulting conclusions are consideredas ours" (Mercier 2009, 117; my translation) and will be more easily accepted than ifthey had been explicitly communicated. In other words, going back to examples (4ac), it may well be that A would have greater success if he only said (4a) and let B draw
his own conclusion, rather than adding (4b) or simply saying (4c). Mercier adds (2009,118. My translation): "The less important the communicator's role in the formation of
the conclusion by the addressee, the more the addressee will accept the conclusion.
Maximally using implicit elements is a risky tactic, because in some cases, the addressee will not draw the intended conclusion, but it can be very efficient". Indeed, given
the egocentric bias, when the addressee already has reached a conclusion which is not
the one the speaker would like him or her to adopt, the speaker's best chance may be touse implicit rather than explicit communication. Additionally, the very fact that the
speaker wants the addressee to adopt a different conclusion would lead the addressee, if
he or she knew it, to reject that different conclusion. In other words, the speaker has
better chances of success, if he deceives his addressee on his intentions to change theaddressee's mind on this specific point. Thus, he has better chances of success if hemanipulates his addressee by hiding his further intention. Hence, though in principle
argumentation and manipulation are not necessarily linked, practically they will often
occur simultaneously.

A Relevance-Theoretic Account of the Evolution of Implicit Communication

8.

15

A multi-layered account of collaboration, argumentation, manipulation, and cooperation

Mercier and Sperber (Mercier 2009, Mercier and Sperber in press) note that argumentation most naturally happens when there is a general agreement about the goal of acollaborative action, but agreement still has to be reached as to the best way of attaining this goal. As we have seen in the previous section, argumentation is often accompanied by manipulation, though both argumentation and manipulation suppose successful cooperative communication in the Gricean sense.
At this point, let me introduce some terminological clarifications. Going back to
Krebs and Dawkins' initial notion of manipulation, it merely stated that manipulationconsists in the communicator endeavoring to control (or at least influence) the addressee's behavior to his own advantage. This, it should be clear, is wide enough to include
argumentation in Mercier and Sperber's sense. As stated above, manipulation can be
hostile (leading to behavior that is advantageous to the communicator, but detrimental
to the addressee) or non-hostile (leading to behavior either advantageous to both or advantageous to the communicator, and neutral to the addressee). And, of course, manipulation can only be the basis for the evolution of communication if it is mainly nonhostile: in other words, hostile manipulation can (and does) occur, but non-hostile manipulation has to be the general case. Krebs and Dawkins assume (as do Mercier andSperber) that non-hostile manipulation is, quite simply, cooperation. Though Krebs andDawkins' version is certainly not cooperation in the Gricean sense (see note 11), in humans, non-hostile manipulation seems to correspond to argumentation in Mercier andSperber's sense. Argumentation will then be characterized as communication targetingarguments, i.e., information whose content is seen by the communicator as a reason fora specific behavior that the communicator wants the addressee to perform. Reasoning
is basically used in the production and evaluation of arguments.
The communicator can use four basic strategies:i.

making his argument entirely explicit by explicitly indicating (using logical andpragmatic connectives) the articulation of the reason and the conclusion hewants the addressee to draw from it (as in example (4c));ii. making his argument largely explicit by explicitly communicating the reason
and the conclusion he wants his addressee to draw from it (as in example (4ab));iii. making his argument partly explicit by explicitly communicating the reason,and leaving the addressee to draw the conclusion (as in example (4a));iv. making his argument implicit by implicitly communicating the reason and leaving the addressee to draw both the reason and the conclusion (as in examples(1), (2) and (3)).
All of these strategies have advantages and disadvantages:

a.

b.

c.

d.

when the communicator chooses the entirely explicit strategy, he risks the addressee negatively evaluating the articulation of the reason and the conclusion(considering that the communicator's reasoning as articulated is invalid), rejecting the conclusion, or even rejecting the reason;
when the communicator chooses the largely explicit strategy, he risks the addressee rejecting the conclusion, or even rejecting the reason;
when the communicator chooses the partly explicit strategy, he risks the addressee not drawing the conclusion, or rejecting the reason, but given the egocentric bias, he runs less risk of the addressee rejecting the conclusion if theaddressee draws it, provided the addressee accepts the reason;
when the communicator chooses the implicit strategy, he risks the addressee
not drawing the reason, or drawing the reason but not the conclusion, but, given the egocentric bias, he runs less risk of the addressee rejecting the reason or
the conclusion if the addressee actually draws either or both of them.

In any episode of argumentation, one can distinguish between proximate intentions (basically, these are the primary and secondary Gricean intentions, or the informative andcommunicative intentions) and ultimate intentions (these concern the behavior that thecommunicator intends to induce in his addressee). The four strategies above can be
distinguished as to how explicit they are regarding the communicator's ultimate
intentions: 19 in the entirely and the largely explicit strategies, they are explicitly communicated; in the partly explicit strategy, they are not communicated, but it may be difficult for the communicator to deny having them, given that he has explicitly communicated the reason; finally, in the implicit strategy, the ultimate intention is not only notcommunicated, it can be denied, because the reason is not explicitly communicated. In
other words, in the implicit strategy, deception (by hiding information) is involved concerning the communicator's ultimate intention.
In other words, these are cases in which there is non-hostile manipulation (and argumentation) with deception as to the communicator's ultimate intentions: in this case,arguably, there is manipulation in the usual vernacular sense. As said before (see §7),
this will occur fairly often and it explains why language allows implicit communication.
Thus we come to a short story regarding the evolution of language as the only animalcommunication system allowing implicit communication: humans, as social animals, depend on one another and more often than not engage in collaborative actions; this requires them to reach agreement not only regarding the goal of these collaborative actions, but also regarding the choice of means; such agreement can only be reached bycommunication of reasons, i.e., with argumentation; the very fact that most human activity is collaborative opens it to the possibility of hostile manipulation; this has led to19

As we saw (see §6), proximate intentions cannot be the object of deception.

A Relevance-Theoretic Account of the Evolution of Implicit Communication17

the development of preventive mechanisms such as the evaluation of arguments as reasons and to the egocentric bias; the egocentric bias leads to a preference for one's own
beliefs and will induce a preference for beliefs which one has reached by oneself; this
explains why it may be advantageous for the communicator to use implicit communication: it allows him to induce in his addressee beliefs (i.e., reasons and conclusions)which the addressee having reached them by himself will be more prone to accept andto hide his ultimate intentions regarding the conclusion he wants the addressee to reachas to the future course of her action.

9.

Conclusion

If Mercier and Sperber are right regarding both the evolution of reasoning and theargumentative nature of public languages, the existence of implicit communication
makes perfect sense. Implicit communication is a way for the communicator to hide the(possibly benevolent) ultimate intentions that he has regarding the addressee's behavior.
This allows for widespread (and usually benevolent and non-hostile) manipulation.
To sum up, the basic idea is the following: the uniqueness of implicit communication to language gives a clue as to why linguistic communication evolved. Most current
scenarios of language evolution are so-called "social" scenarios, though that rather wide
term covers a variety of meanings. However, behind this variety lies the common ideathat the main motor of language evolution is cooperation, understood as involving altruism in the biological sense, that is, behaviors that are costly to the agent and beneficial
to the recipient. In my view, the existence of implicit communication should lead to amore layered view, where manipulation plays as much a role as cooperation in the evolution of linguistic communication. In agreement with the recent theory of argumentation proposed by Sperber and Mercier for the evolution of human reasoning abilities,
which strongly suggests that language and reasoning abilities coevolved to allow people
to come to an agreement, I propose that implicit communication allows the speaker tohide his intentions to persuade the hearer that the course of action the speaker proposes
is better than the one the hearer contemplates (i.e., to manipulate the hearer). The
speaker can thus lead the hearer to change his mind, by communicating the relevant information implicitly, rather than explicitly. This does not mean however that implicit
communication can only be found in competitive contexts, given the possibility described above of, so to speak, benevolent manipulation. This theory accounts for thevery existence of implicit communication and it also explains facts such as the following: implicit communication is often used in polite exchanges, e.g., indirect requests,
such as Could you pass the salt, (please)?, where a direct request might be seen as rude
and where implicit communication allows the speaker to implicitly communicate his request without making his intention that the hearer obey his request too clearly a markof dominance; implicit communication often communicates not only an (implicit) refusal, but also a general reason for the refusal, thus making it innocuous as it is not seen

18

as directly linked to the present offer and the person making it. In such cases, manipulation need not be deceptive. In other words, an ability, implicit communication, initially evolved for hiding manipulative intentions, is now also occasionally used without thistype of deception.
Thus, under the scenario outlined above (see §8), we get the following layered picture: collaboration ___. collective decision making ___. argumentation ___. manipulation ___.
implicit communication.

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