Modus Tollens, Modus Shmollens: Contrapositive
reasoning and the pragmatics of negation
Jean-Franc¸ois Bonnefon and Gae¨lle Villejoubert
LTC-CNRS, Toulouse, France
The utterance of a negative statement invites the pragmatic inference that some
reason exists for the proposition it negates to be true; this pragmatic inference
paves the way for the logically unexpected Modus Shmollens inference: ‘‘If p
then q; not-q; therefore, p.’’ Experiment 1 shows that a majority of reasoners
endorse Modus Shmollens from an explicit major conditional premise and a
negative utterance as a minor premise: e.g., reasoners conclude that ‘‘the soup
tastes like garlic’’ from the premises ‘‘If a soup tastes like garlic, then there is
garlic in the soup; Carole tells Didier that there is no garlic in the soup they are
eating.’’ Experiment 2 shows that this effect is mediated by the derivation of a
pragmatic inference from negation. We discuss how theories of conditional
reasoning can integrate such a pragmatic effect.
This article does not constitute an attempt at curing teenage angst. Of
course, you probably never expected that it would—and as a consequence,
you may have found that first sentence rather incongruous. Indeed, we
seldom deny what nobody believes to be true—rather, we often use negative
statements to correct an inaccurate belief we assume the listener to hold. In
this article we will show that this property of negation plays a crucial role in
a seemingly outrageous fallacy we will call Modus Shmollens: ‘‘If p then q;
it is not the case that q; therefore, p is true’’—following Lance Rips’ (1988,
p. 116) coining of the term ‘‘Modus Shmonens’’ for the inference ‘‘If p then
q; p is true; therefore, it is not the case that q.’’ We begin with some
introductory remarks on the relations between pragmatics and reasoning.
We then turn to the gist of our argument, i.e., the distinction between
Correspondence should be addressed to Jean-Franc¸ois Bonnefon, Laboratoire Travail et
Cognition, Maison de la Recherche, 5 alle´es A. Machado, 31058 Toulouse Cedex 9, France.
E-mail: bonnefon@univtlse2.fr
We thank Jonathan Evans, Simon Handley, Guy Politzer, Valerie Thompson, and one
anonymous reviewer for helpful comments prior versions of this article.
THINKING & REASONING, 2007, 13 (2), 207 – 222
 2007 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business
http://www.psypress.com/tar DOI: 10.1080/13546780601069488

negative utterances and negated propositions. Once we have delineated the
specific pragmatic inferences raised by negative utterances, compared to
negated propositions, we will be in a position to predict when and why
reasoners accept Modus Shmollens. We will then report two experiments
testing these predictions.
PRAGMATICS AND REASONING
Linguistic pragmatics has a key role to play in the psychology of reasoning
in general, and in the psychology of conditional reasoning in particular. A
psychological theory of conditional reasoning can only be complete with a
pragmatic component explaining how reasoners convert verbal input (the
premises of the reasoning process) into the format of the inferential
machinery on which the theory operates (e.g., mental models, conditional
probabilities, logical propositions). In the words of Thompson (2000,
pp. 211 – 212), among many other similar statements: ‘‘Clearly, such an
interpretive process largely determines which inferences are made and not
made; consequently, a complete theory of deductive reasoning requires a
well-developed model of interpretation.’’
Within the psychology of reasoning, conversational pragmatics was
originally called upon to explain a variety of puzzling inferential behaviours,
mainly observed within the Piagetian paradigm (Piaget & Inhelder, 1964) or
the Heuristic and Biases program (Kahneman, Slovic, & Tversky, 1982), or
related to Peter Wason’s Four-card and 2 – 4 – 6 tasks (Wason, 1960,
1966)—for extensive reviews of this early use of pragmatics, see Hilton
(1995), and Politzer (2004).
An important consequence of this trend of research was that theorists
gradually distinguished core reasoning phenomena (that their inferential
machinery had to account for) from the mere pragmatic phenomena that
could be left unaccounted for, as long as the theory explicitly included a
pragmatic component, however underspecified this component. While
pragmatics undoubtedly transformed the psychology of reasoning, research
on pragmatic components is still needed, in order for these components not
to be chiefly a convenient label for explaining away phenomena that do not
fit in the core of their parent theories.
This objective requires a shift in research strategy: Rather than going
from well-known reasoning or judgemental effects to their pragmatic
explanation (Bonnefon & Hilton, 2002; Bonnefon & Villejoubert, 2006), we
need to predict novel effects from pragmatic considerations, and thence
indicate how such findings can enrich the pragmatic layer of existing
theories of reasoning (Bonnefon & Hilton, 2004; Hilton, Kemmelmeier, &
Bonnefon, 2005; Hilton, Villejoubert, & Bonnefon, 2005). With that
objective in mind, we will now consider one pragmatic specificity of
208 BONNEFON AND VILLEJOUBERT

negative statements, and show how it is likely to yield one logically
outrageous inference.
NEGATIVE UTTERANCES VS NEGATED PROPOSITIONS
Conversational pragmatics deals with utterances rather than propositions:
A pragmatic approach to reasoning capitalises on the fact that reasoners
make inferences not only from premises (propositions), but also from the
very fact that these premises were asserted (utterances). Consequently, a
pragmatic approach to reasoning is appropriate as soon as the inferences
made from the premises mismatch the inferences invited from the assertion
of these premises. Such is the case with negative utterances, which invite
inferences beyond those yielded by the negated propositions they embed.
As was pointed out in the introduction, we often use negative utterances
to correct an inaccurate belief of the listener. In other words, one natural
way for the statement ‘‘it is not the case that q’’ to be felicitous is that the
listener can be assumed to believe q. This principle is not included in the
semantics of negation (Horn, 1989), and it does not amount to treating
negation as the denial of a presupposition, in the semantic sense. Rather,
what is denied is a belief the speaker assumes the addressee to hold, what
Stalnaker (1991) called a pragmatic presupposition.
Early psycholinguistic experiments (De Villier & Tager Flusberg, 1975;
Johnson-Laird & Tridgell, 1972; Wason, 1965, 1972) showed that negations
were easier and quicker to process when the context (linguistic and
otherwise) made it possible to interpret negation as a correction of
the listener’s expectations. Quoting De Villier and Tager Flusberg (1975,
p. 279), the statement ‘‘I didn’t drive to work’’ is:
more plausible, and consequently easier to comprehend, if it is made by
someone who normally drives rather than by someone who commutes by
train. [. . . ] Negative statements are generally used to point out discrepancies
between a listener’s presumed expectations and the facts.
Similarly, Wason (1965) asserted that the function of negative statements is
generally to emphasise that a fact is contrary to expectation, and Strawson
(1952) pointed out that the primary use of not is to contradict, cancel, or
correct a suggestion of one’s own or another’s. This pragmatic property of
negative statements was also documented by Givon (1978), who used the
following example: Saying that ‘‘Sally is pregnant’’ is felicitous even when
the listener is completely neutral about the possibility of Sally being
pregnant, but saying that ‘‘Sally is not pregnant’’ is not. A typical response
in that case would be: ‘‘Wait a minute—was she supposed to be?’’ (See also
Glenberg, Robertson, Jansen, & Johnson-Glenberg, 1999; Gualmini, 2004;
Israel, 2004).
MODUS SHMOLLENS AND PRAGMATICS OF NEGATION 209

Thus, negative statements of the form ‘‘it is not the case that q’’ often
trigger the inference that the speaker assumes the listener to believe q. This
use of negation as a way to deny pragmatic presuppositions has already
been put to good use by Evans (1989) to explain the phenomenon of
matching bias in conditional reasoning, on which see Evans (1998) for a
review. However, we will now take this one step further and ask why
someone who asserts that ‘‘it is not the case that q’’ might assume the
listener believes q. The most natural answer is that some reason p to believe
q must be manifest to both speaker and listener. That is, the context of the
utterance has a feature p such that p usually makes people think q, and the
statement ‘‘it is not the case that q’’ can be paraphrased as: ‘‘Even though p
might let you think that q, in reality, it is not the case that q.’’ Hence,
denying that q is true will invite the pragmatic inference that some reason p
to believe q exists; and this is the point from which inferences will go awry,
as we will now see.
MODUS TOLLENS, MODUS SHMOLLENS
A natural way to express that p is a reason to believe q is to embed both
propositions in an epistemic conditional (also called inferential, or evidential) of
the form ‘‘if p, then q’’ (Cummins, 1995; Dancygier, 1998; Declerck & Reed,
2001; Pearl, 1988; Politzer & Bonnefon, 2006; Sweetser, 1990; Thompson,
1994). Rather than expressing a causal relation between p and q (i.e., the
occurrence of p causes the occurrence of q), epistemic conditionals express that
believing p is a reason to believe q too. Let us consider the conditional ‘‘if a soup
tastes like garlic, then there is garlic in the soup.’’ This conditional does not
express that the taste of garlic causes the presence of garlic. Rather, it expresses
that the taste of garlic is a cue to the presence of garlic.
Now let us imagine that Carole and Didier are eating a soup, and that
Carole tells Didier there is no garlic in this soup. This negative utterance
triggers the pragmatic inference that a reason exists in this context for Didier
to believe there is garlic in the soup. A taste of garlic would be a very good
candidate. Thus, we might be tempted to conclude that the soup tastes like
garlic. But let us take a closer look at this apparently reasonable inference.
From the premises ‘‘There is no garlic in the soup’’ and ‘‘If a soup tastes like
garlic, then there is garlic in the soup’’, we have just concluded that ‘‘the
soup tastes like garlic’’. In abstract terms, we have concluded p from if p
then q and not-q. While this inference is quite sensible in a conversational
context, it is a logical heresy—in fact, it is so fallacious that it has not even
been given a name as a fallacy, hence our coining of the term Modus
Shmollens.
We are now in a position to predict that reasoners will endorse the
Modus Shmollens inference from an epistemic conditional ‘‘if p, then q’’ when
210 BONNEFON AND VILLEJOUBERT

the minor premise not-q is an utterance rather than a mere sentence. Indeed, if
in our soup example the minor premise ‘‘there is no garlic in the soup’’ is
not uttered by one character to another, the pragmatic inferences from
negation should not be invited, and Modus Shmollens should not be
accepted. Additionally, we would like to show that the endorsement of
the Modus Shmollens conclusion requires the explicit presence in the
problem of the major conditional premise (thus preventing the objection
that we are dealing with a general pragmatic issue rather than with
conditional reasoning in particular). Experiment 1 was conducted to test
these two claims.
EXPERIMENT 1
Method
Participants were 60 students at the university of Toulouse (37 women and
23 men, mean age¼ 21.6, SD¼ 3.2), who were individually recruited on
campus by research assistants. Participants responded to four problems,
following a 26 2 full factorial design. The problems differed in the way the
premises were introduced. The major conditional premise was either explicit
or implicit, and the minor categorical premise was either an utterance or a
mere sentence. Here is an example of a problem with an explicit major
premise and an utterance as a minor premise:
Ge´raldine and Henri are listening to a record. Generally speaking, if Mick
Jagger is singing on a record, then it is a Rolling Stones record. Ge´raldine tells
Henri that this record is not a Rolling Stones record.
In the major premise: implicit variants of this problem, the sentence
‘‘Generally speaking, if Mick Jagger is singing on a record, then it is a
Rolling Stones record’’ was omitted. In the minor premise: sentence variants
of this problem, the sentence ‘‘Ge´raldine tells Henri that this record is not a
Rolling Stones record’’ was replaced with ‘‘This record is not a Rolling
Stones record.’’
The four problems were embedded in four different contexts (see
Appendix). Four different versions of the questionnaire were created, so
that each problem appeared once in each context.
After reading each problem, participants judged to which extent a
proposed conclusion appeared to be correct, from the information given in
the problem. The proposed conclusion was always the affirmation of the
antecedent of the (explicit or implicit) conditional premise, for example:
Mick Jagger is singing on this record.
MODUS SHMOLLENS AND PRAGMATICS OF NEGATION 211

Participants gave ratings from 1 to 5, where 1 meant ‘‘I think the conclusion
is absolutely incorrect’’, 2 meant ‘‘I rather think the conclusion is incorrect’’,
3 meant ‘‘I think that the conclusion could be correct as well as incorrect’’,
4 meant ‘‘I rather think the conclusion is correct’’, and 5 meant ‘‘I think the
conclusion is absolutely correct’’. The experiment was conducted in French.
Results
Two participants were categorised as multivariate outliers using the
Mahalanobis distance method (Mahalanobis, 1936). These two participants
were omitted in subsequent analyses.
An analysis of variance revealed that the acceptance rating of the Modus
Shmollens conclusion was reliably greater when the conditional premise was
explicit, F(1, 57)¼ 20.6, p5 .001, Z2¼ .27, and when the minor premise was
an utterance rather than a sentence, F(1, 57)¼ 13.0, p5 .001, Z2¼ .19. (See
Table 1 for descriptive statistics; all the p values we report are two tailed for
F tests, and one tailed otherwise.) Furthermore, the interaction of these two
variables reliably affected acceptance rating in the expected direction; Modus
Shmollens acceptance is especially high when the major premise is explicit and
the minor premise is an utterance, F(1, 57)¼ 2.9, p5 .05, Z2¼ .07.
Another way to look at the results is to consider the endorsement of the
Modus Shmollens conclusion as a binary dependent variable: Only
participants who give ratings of 4 or 5 express their endorsement of this
conclusion. Thus, by dichotomising the acceptance ratings with a cut-off at 4
we can consider how our independent variables influenced the endorsement
of the Modus Shmollens conclusion. As Table 1 shows (last column),
explicit major premises and utterances as minor premises independently
increased the base endorsement rate of 12%—but only when both these
conditions were met did a majority of participants (55%) endorse the
Modus Shmollens conclusion.
TABLE 1
Acceptance ratings and frequencies of endorsement
Mean SD % of 4 – 5 ratings
Major: Implicit
Minor: Sentence 2.2 1.2 12
Minor: Utterance 2.6 1.5 19
Major: Explicit
Minor: Sentence 2.5 1.3 28
Minor: Utterance 3.4 1.4 55
Acceptance ratings (5-point scale) and frequencies of endorsement of the Modus Shmollens
conclusion, as a function of type of major and minor premise. n¼ 58.
212 BONNEFON AND VILLEJOUBERT

The results of Experiment 1 support our prediction that reasoners will
endorse the Modus Shmollens inference from an epistemic conditional ‘‘if p,
then q’’ when the minor premise not-q is an utterance rather than a mere
sentence. Furthermore, the endorsement of Modus Shmollens is much weaker
when the major conditional premise is not explicitly introduced in the problem.
One plausible explanation for this weaker effect is that participants who were
not provided explicitly with the major conditional premise ‘‘if p, then q’’ might
have searched themselves for some plausible antecedent that would normally
lead to q. These participants might have ended up with some p0, different from
p, and such that if p0, then q. As a consequence, these participants rejected the
conclusion p, not because it was an invalid Modus Shmollens conclusion, but
because they preferred another invalid Modus Shmollens conclusion.
Now that Experiment 1 has demonstrated the basic phenomenon of
Modus Shmollens endorsement, we wish to provide an even more direct
demonstration that the derivation of Modus Shmollens results from the
pragmatics of negation. Experiment 2 was conducted to provide such a
demonstration. In addition to replicating the key result of Experiment 1,
Experiment 2 will consider whether the effect of premise introduction
(utterance or sentence) on accepting the Modus Shmollens conclusion is
mediated by the derivation of the pragmatic inference from negation.
EXPERIMENT 2
Method
Participants were 45 volunteer students at the University of Albi (43 women
and 2 men, mean age¼ 23.5, SD¼ 7.2). Participants responded to one problem
with a sentence as a minor premise, then to one problem with an utterance as a
minor premise. (Major conditional premises were always explicit in Experiment
2.) In one half of the questionnaires, the first problem used the Garlic Soup
context of Experiment 1, and the second problem used the Panther context of
Experiment 1 (see later); the reverse was true for the other half of the
questionnaires. Participants judged the correctness of the same conclusions as
in Experiment 1, on a similar 5-point scale. In addition, for each problem,
participants answered a yes or no question assessing whether they had derived a
pragmatic inference from the minor premise. For example, after having read:
Carole andDidier are eating a soup.Generally speaking, if a soup tastes like garlic,
then there is garlic in the soup. Carole tellsDidier that there is no garlic in the soup,
participants were first asked: Is it a correct conclusion that the soup tastes
like garlic? And then: Is it true that, according to Carole, Didier thought
there was garlic in the soup?
The experiment was conducted in French, during class time.
MODUS SHMOLLENS AND PRAGMATICS OF NEGATION 213

Results
Just as in Experiment 1, the way the minor premise was introduced made a
significant difference to the willingness of participants to endorse the Modus
Shmollens conclusion. Mean agreement with the Modus Shmollens
conclusion was 2.6 (SD¼ 1.6) when the minor was an utterance, but only
2.1 (SD¼ 1.4) when the minor was a mere sentence, t(44)¼ 1.97, p¼ .03,
d¼ 0.33. The endorsement rate of Modus Shmollens (i.e., the frequency of
4 – 5 ratings) was 31% for utterances, and only 15% for sentences.
While 70% participants derived the pragmatic inference from negation
when the minor premise was an utterance, a reliably lower 36% did so when
it was a mere sentence (McNemar, p¼ .002, h¼ 0.7). Averaging across the
90 conclusions provided by the 45 participants, agreement with the Modus
Shmollens conclusion was 2.8 (SD¼ 1.4) when the pragmatic inference was
derived (with 33% of 4 – 5 ratings), and only 2.0 (SD¼ 1.6) when this
inference was not derived (with 15% of 4 – 5 ratings), t(87)¼ 2.6, p5 .01.
We conducted a series of three regressions analyses on the 90 sets of
responses we collected (Baron & Kenny, 1986), using effect codings for
premise introduction (sentence¼71, utterance¼þ1) and derivation of the
pragmatic inference (no¼71, yes¼þ1). The direct effect of premise
introduction on Modus Shmollens acceptance was only tangential, b¼ .14,
t¼ 1.33, p5 .10. (Note, however, that the statistical significance of this
direct effect is not a strict requirement for concluding statistical mediation.)
The effect of premise introduction on the derivation of the pragmatic
inference was significant, b¼ .35, t¼ 3.48, p5 .001. In the third regression,
premise introduction and pragmatic inference derivation were entered
simultaneously. Pragmatic inference derivation was a reliable predictor of
Modus Shmollens acceptance, b¼ .24, t¼ 2.20, p5 .05, which was not the
case for premise introduction, b¼ .06, t¼ 0.55 (see Figure 1). Thus, the
contribution of premise introduction to Modus Shmollens acceptance
dropped from .14 to .06 when the derivation of the pragmatic inference was
controlled for. This decrease is significant according to the Sobel test, whose
value was 1.9, p5 .05 (Sobel, 1982). Consequently, all the conditions are
met for concluding statistical mediation: In line with our theoretical
analysis, premise introduction affects Modus Shmollens acceptance through
the derivation of a pragmatic inference from negation.
GENERAL DISCUSSION
Two experiments showed that when the negation of some state of affairs is
presented as a statement made in a conversation, a majority of reasoners
endorse the Modus Shmollens inference, which makes no sense from a
logical perspective but perfect sense from a conversational perspective.
214 BONNEFON AND VILLEJOUBERT

For example, a majority of reasoners endorsed the conclusion ‘‘the animal
looks like a panther’’ from the following premises:
Alice and Benjamin are looking at an animal in a zoo. Generally speaking, if
an animal looks like a panther, then it is a panther. Alice tells Benjamin that
this animal is not a panther.
However, they no longer endorsed this conclusion when the words ‘‘Alice
tells Benjamin that’’ were omitted from the problem. Furthermore, a second
experiment established that the endorsement of the Modus Shmollens
inference is due to the derivation of a pragmatic inference. Since negation is
often used in conversation to correct some inaccurate belief of the listener,
reasoners who saw the conversational version of the problem were likely to
agree that, according to Alice, Benjamin thought the animal was a panther.
This pragmatic inference, in turn, was responsible for their endorsement of
the Modus Shmollens conclusion.
These two experiments serve as a powerful demonstration of conversa-
tional influences on reasoning, but also as a demonstration of their limits.
Only a weak pragmatic effect was found when the problem was not explicitly
framed as a conversation: Most participants could apparently disregard the
pragmatic reading of the negation (or possibly never considered it at all)
when the problem did not mention an explicit conversational setting. Just as
background knowledge effects can be limited by instructions that emphasise
the logical nature of the task (see Chapter 6 in Evans & Over, 2004),
conversational effects are limited when the task does not explicitly refer to a
conversational setting (see also Experiment 4 in Stevenson & Over, 2001).
Indeed, the information we use as an input to our reasoning comes from a
variety of sources in addition to discourse; for example, memory,
perception, or prior inferences. Most of us know that Shere Khan is not a
panther, although we may have come to this knowledge through many
different routes. Some were just told that Shere Khan was not a panther
Figure 1. The type of minor premise (statement or mere sentence) has a mediated effect on
agreement with the Modus Shmollens conclusion, the mediating variable being the derivation of
a pragmatic inference from negation. Coefficients are standardised bs, N¼ 90, {p5 .10,
*p5 .05, **p5 .001.
MODUS SHMOLLENS AND PRAGMATICS OF NEGATION 215

(discourse). Some remember that fact from the book (memory). Some
discover it when watching the movie (perception). Some may reason that it
cannot be a panther because Bagheera is already a panther, and there is only
one panther in the story (inference). Conversational effects are unlikely to
occur in all but the first case.
However, conversational effects do arise sometimes, and theories of
conditional reasoning should account for such logically unexpected
inferences as Modus Shmollens. In the final section of this article we will
consider two routes thereto: the dual-negation, single-process route; and the
single-negation, dual-process route. Before that, we will discuss the fact that
our two experiments used epistemic conditionals, and consider whether the
pragmatics of negation is likely to influence reasoning with other types of
conditionals.
Beyond epistemic conditionals
Our two experiments demonstrated that a majority of reasoners endorsed
the conclusion ‘‘p is true’’ from premises of the form ‘‘if p then q; Person A
tells Person B that q is not the case’’, where the conditional ‘‘if p then q’’ is of
the epistemic type. With such conditionals, p is seen as diagnostic of the
truth of q, rather than, for instance, a cause for the occurrence of q. We first
wish to consider the possibility that some reasoners might have reversed
the epistemic conditionals into their causal form, and derived conclusions
from this causal interpretation. For example, reasoners presented with the
problem:
E´milie and Fabrice are talking about one of their professors. Generally
speaking, if a professor has a Swedish name, then she is a Swede. E´milie tells
Fabrice that the professor is not a Swede,
might have reversed the direction of the conditional from epistemic to
causal:
E´milie and Fabrice are talking about one of their professors. Generally
speaking, if a professor is a Swede, then she has a Swedish name. E´milie tells
Fabrice that the professor is not a Swede.
From such an interpretation, the conclusion ‘‘the professor has a Swedish
name’’ is no longer a Modus Shmollens conclusion; but it is not a logically
valid conclusion either. In fact, it is a fallacy nearly as odd and as
undocumented as Modus Shmollens, one that we might call Shnying the
Antecedent: If p, then q; not-p; therefore, q. Thus, if indeed some
participants reversed our epistemic conditionals into their causal form,
their reasoning showed the same spectacular conversational effects as that of
other participants.
216 BONNEFON AND VILLEJOUBERT

We now briefly consider the possibility of observing Modus Shmollens
inferences outside the epistemic or causal domain, or more precisely, in the
deontic domain. It seems plausible that the conversational negation of an
interdiction will trigger the pragmatic inference that some reason exists in
the context for the listener to believe the interdiction was in effect (see
Verstraete, 2005, for the pragmatic expectations raised by denying an
obligation or a permission). For example, consider the following problem,
involving a deontic conditional:
Carole and Didier are talking about one of their classmates. Generally
speaking, if one is a Muslim, one is forbidden to eat pork. Carole tells Didier
that their classmate is not forbidden to eat pork.
The chain of reasoning here is very similar to the one we have considered
in detail in this article. For Carole’s negative statement to be felicitous, she
must believe that Didier thought their classmate was forbidden to eat pork.
One salient reason for Didier to think so (and one that is explicit in the
problem) would be that their classmate is a Muslim. Hence, it seems
conversationally reasonable to assume that the classmate is a Muslim. But
this, of course, is the deontic variant of Modus Shmollens: ‘‘if p then
forbidden(q); it is not the case that forbidden(q); therefore, p is the case.’’
Dual negation or dual process?
We have demonstrated a spectacular difference between the conditional
consequences of a negated proposition (‘‘it is not the case that q’’) and the
conditional consequences of a negative utterance (‘‘Person A tells Person B
that it is not the case that q’’). Although this result readily makes sense from
a pragmatic perspective, it is difficult to see how current theories of
conditional reasoning will integrate it within their pragmatic layer. We now
suggest that accounting for Modus Shmollens will necessitate taking either
one of two routes: the dual-negation, single-process route; or the single-
negation, dual-process route.
There are two perspectives one can take towards the fact that negated
propositions have different consequences from negative utterances. The first
perspective explains these different consequences by assuming different
representations for conversational and logical negation; the second one
assumes that conversational and logical negations are represented in the
same way, but processed by two different mechanisms.
As an account of conditional reasoning, Mental Model Theory (Johnson-
Laird & Byrne, 2002; see also Bonnefon, 2004; Evans, Over, & Handley,
2005) takes a representational stance to pragmatic effects. If a set of
premises yields different conclusions as a function of whether one of its
MODUS SHMOLLENS AND PRAGMATICS OF NEGATION 217

premises is part of a conversation, then it must be that this premise is not
represented by the same mental models when it is part of a conversation. We
thus need to assume that different mental models will stand for the problem
‘‘if p then q; it is not the case that q’’ and for the problem ‘‘if p then q; Person
A tells Person B that it is not the case that q’’. Since the conditional is the
same in both problems, its models should be the same. Therefore, the
difference between the two problems must boil down to a difference between
the models of ‘‘it is not the case that q’’ and the models of ‘‘Person A tells
Person B that it is not the case that q’’.
The model of ‘‘it is not the case that q’’ is simply :q, where : is a
negation tag. What then can be the models of ‘‘Person A tells Person B
that it is not the case that q’’? There are no epistemic operators such as
Assert(:q) or Know(:q) in Mental Model Theory, which would help to
distinguish conversational premises from non-conversational premises.
Consequently, it seems that there is only one way to distinguish ‘‘it is not
the case that q’’ from ‘‘Person A tells Person B that it is not the case that q’’;
namely, to use a distinct tag for negations that are used in a conversational
setting (e.g., *q instead of :q). Obviously, the fact that this seems to be
the only solution to the problem does not mean it is a good solution.
First, everything has still to be done to define how models tagged with a
conversational negation marker combine with other models. Second,
proponents of Mental Model Theory (Barouillet & Lecas, 1998) have
already raised objections to the use of propositional negation markers
within models, and it might not be a good step to introduce several such
markers where one is already problematic.
An alternative to postulating two types of negation that go through one
reasoning process is to consider that negation will go through a different
reasoning process as a function of whether it occurs in a conversational
context or not.
The dual-process approach to reasoning (Best, 2005; Evans, 2005;
Evans & Over, 1996, 2004; Klaczynski & Daniel, 2005; Klaczynski,
Schuneman, & Daniel, 2004; Schroyens, Schaeken, & Handley, 2003;
Sloman, 1996, 2002; Stanovich, 1999; Thompson, Evans, & Handley, 2005)
assume that inferences can reflect, at different times, the operation of one set
of mental processes (System1) or the other (System2). The fast, association-
driven System1 is triggered whenever it encounters information it can
process, and is rather undemanding of cognitive resources. The analytic and
reason-oriented System2 must be deliberately engaged and controlled, is
slow, and is demanding of capacity. System1 operates on contextualised
tasks, taking into account semantic content and, most importantly for our
present purpose, conversational principles. The operation of System2, in
contrast, depends on the decontextualisation of the task, and on the
activation of abstract rules of inference.
218 BONNEFON AND VILLEJOUBERT

Within this framework, we can explain our main findings as a difference
between the System1 and the System2 processing of negation. When a fact q
is denied in a conversational context, System1 automatically looks for a fact
p that is usually diagnostic of (associated with) fact q, and comes to the
conclusion that p might well be the case. Of course, this search process can
be influenced by directly providing reasoners with a candidate fact p, as we
did when we presented participants with problems of the form: ‘‘If p, then q;
Person A tells Person B that it is not the case that q.’’ In such a situation,
System1 finds that p is an acceptable conclusion, and all happens as if
reasoners endorsed the Modus Shmollens fallacy.
Now, when a fact q is denied outside a conversational context, either
(a) System1 processing of conversational inferences is not triggered, since
the situation does not meet the requirements for such a processing, or
(b) System1 does process the pragmatic inferences from negation, but its
output is inhibited by a System2 effort at decontextualisation, which is made
easier by the absence of a conversational context. In both cases, reasoners
will resist the Modus Shmollens fallacy. They may even draw the logically
valid Modus Tollens conclusion, if they have some ready access to an
abstract strategy for reductio ad absurdum.
Last words
Starting from the pragmatic reading of negation as a denial of expectation,
we have provided a powerful demonstration of how conversational
principles can influence conditional inference. Merely introducing a premise
not-q as being uttered by one individual to another was enough for
participants’ inferences to swing from Modus Tollens to its conversational
counterpart, Modus Shmollens. We have suggested considering this result
from a dual-process perspective. When facts are denied as part of a
conversation (negative utterances), System1 conversational/associative
processes fire and lead reasoners to endorse Modus Shmollens. When facts
are denied outside a conversational context (negated propositions), System1
does not fire (or its output is inhibited), and reasoners resist Modus
Shmollens.
Manuscript received 3 July 2006
Revised manuscript received 7 September 2006
REFERENCES
Baron, R. M., & Kenny, D. A. (1986). The moderator –mediator variable distinction in social
psychological research: Conceptual, strategic, and statistical considerations. Journal of
Personality and Social Psychology, 51, 1173 – 1182.
MODUS SHMOLLENS AND PRAGMATICS OF NEGATION 219

Barouillet, P., & Lecas, J. F. (1998). How can mental models theory account for content effects
in conditional reasoning? A developmental perspective. Cognition, 67, 209 – 253.
Best, J. (2005). Recognition of proofs in conditional reasoning. Thinking and Reasoning, 11,
326 – 348.
Bonnefon, J. F. (2004). Reinstatement, floating conclusions, and the credulity of mental model
reasoning. Cognitive Science, 28, 621 – 631.
Bonnefon, J. F., & Hilton, D. J. (2002). The suppression of modus ponens as a case of
pragmatic preconditional reasoning. Thinking and Reasoning, 8, 21 – 40.
Bonnefon, J. F., & Hilton, D. J. (2004). Consequential conditionals: Invited and suppressed
inferences from valued outcomes. Journal of Experimental Psychology: Learning, Memory,
and Cognition, 30, 28 – 37.
Bonnefon, J. F., & Villejoubert, G. (2006). Tactful or doubtful? Expectations of politeness
explain the severity bias in the interpretation of probability phrases. Psychological Science,
17, 747 – 751.
Cummins, D. D. (1995). Naı¨ve theories and causal deduction. Memory and Cognition, 23, 646 –
658.
Dancygier, B. (1998). Conditionals and prediction. Time, knowledge, and causation in conditional
constructions. Cambridge, UK: Cambridge University Press.
De Villier, J., & Tager Flusberg, H. (1975). Some facts one simply cannot deny. Journal of Child
Language, 2, 279 – 286.
Declerck, R., & Reed, S. (2001). Conditionals. A comprehensive empirical analysis. Berlin &
New York: Mouton de Gruyter.
Evans, J. St. B. T. (1989). Bias in human reasoning: Causes and consequences. Hove, UK:
Lawrence Erlbaum Associates Ltd.
Evans, J. St. B. T. (1998). Matching bias in conditional reasoning: Do we understand it after 25
years? Thinking and Reasoning, 4, 45 – 82.
Evans, J. St. B. T. (2005). The social and communicative function of conditional statements.
Mind and Society, 4, 97 – 113.
Evans, J. St. B. T., & Over, D. E. (1996). Rationality and reasoning. Hove, UK: Psychology
Press.
Evans, J. St. B. T., & Over, D. E. (2004). If. Oxford, UK: Oxford University Press.
Evans, J. St. B. T., Over, D. E., & Handley, S. J. (2005). Suppositions, extensionality, and
conditionals: A critique of the mental model theory of Johnson-Laird and Byrne (2002).
Psychological Review, 112, 1040 – 1052.
Givon, T. (1978). Negation in language: Pragmatics, function, ontology. In P. Cole (Ed.),
Syntax and semantic: Pragmatics (pp. 69 – 112). New York: Academic Press.
Glenberg, A. M., Robertson, D. A., Jansen, J. L., & Johnson-Glenberg, M. C. (1999). Not
propositions. Journal of Cognitive Systems Research, 1, 19.
Gualmini, A. (2004). Some knowledge children don’t lack. Linguistics, 42, 957 – 982.
Hilton, D. J. (1995). The social context of reasoning: Conversational inference and rational
judgement. Psychological Bulletin, 118, 248 – 271.
Hilton, D. J., Kemmelmeier, M., & Bonnefon, J. F. (2005). Putting ifs to work: Goal-based
relevance in conversational action planning. Journal of Experimental Psychology: General,
135, 388 – 405.
Hilton, D. J., Villejoubert, G., & Bonnefon, J. F. (2005). How to do things with logical
expressions: Creating collective value through coordination. Interaction Studies, 6, 103 – 117.
Horn, L. R. (1989). A natural history of negation. Chicago: University of Chicago Press.
Israel, M. (2004). The pragmatics of polarity. In L. R. Horn & G. Ward (Eds.), The handbook of
pragmatics (pp. 701 – 723). Oxford, UK: Blackwell.
Johnson-Laird, P. N., & Byrne, R. M. J. (2002). Conditionals: A theory of meaning,
pragmatics, and inference. Psychological Review, 109, 646 – 678.
220 BONNEFON AND VILLEJOUBERT

Johnson-Laird, P. N., & Tridgell, J. M. (1972). When negation is easier than affirmation.
Quarterly Journal of Experimental Psychology, 24, 87 – 91.
Kahneman, D., Slovic, P., & Tversky, A. (1982). Judgment under uncertainty: Heuristics and
biases. Cambridge, UK: Cambridge University Press.
Klaczynski, P. A., & Daniel, D. B. (2005). Individual differences in conditional reasoning: A
dual-process account. Thinking and Reasoning, 11, 305 – 325.
Klaczynski, P. A., Schuneman, M. J., & Daniel, D. B. (2004). Theories of conditional
reasoning: A developmental examination of competing hypotheses. Developmental
Psychology, 40, 559 – 571.
Mahalanobis, P. C. (1936). On the generalized distance in statistics. Proceedings of the National
Institute of Science of India, 12, 49 – 55.
Pearl, J. (1988). Probabilistic reasoning in intelligent systems. San Mateo, CA: Morgan
Kaufmann.
Piaget, J., & Inhelder, B. (1964). The early growth of logic in the child: Classification and
seriation. London: Routledge.
Politzer, G. (2004). Reasoning, judgement, and pragmatics. In I. Noveck & D. Sperber (Eds.),
Experimental pragmatics (pp. 94 – 115). London: Palgrave.
Politzer, G., & Bonnefon, J. F. (2006). Two varieties of conditionals and two kinds of defeaters
help reveal two fundamental types of reasoning. Mind and Language, 21, 484 – 503.
Rips, L. J. (1988). Deduction. In R. J. Sternberg & E. E. Smith (Eds.), The psychology of human
thought (pp. 116 – 152). Cambridge, UK: Cambridge University Press.
Schroyens, W., Schaeken, W., & Handley, S. (2003). In search of counterexamples: Deductive
rationality in human reasoning. Quarterly Journal of Experimental Psychology, 56A, 1129 –
1145.
Sloman, S. A. (1996). The empirical case for two systems of reasoning. Psychological Bulletin,
119, 3 – 22.
Sloman, S. A. (2002). Two systems of reasoning. In T. Gilovich & D. Griffin (Eds.), Heuristics
and biases: The psychology of intuitive judgment (pp. 379 – 396). New York: Cambridge
University Press.
Sobel, M. E. (1982). Asymptotic confidence intervals for indirect effects in structural equation
models. In S. Leinhart (Ed.), Sociological methodology 1982 (pp. 290 – 312). San Francisco:
Jossey-Bass.
Stalnaker, R. (1991). Pragmatic presuppositions. In S. Davis (Ed.), Pragmatics: A reader
(pp. 471 – 481). Oxford, UK: Oxford University Press.
Stanovich, K. E. (1999). Who is rational? Studies of individual differences in reasoning. Mahwah,
NJ: Lawrence Erlbaum Associates Inc.
Stevenson, R. J., & Over, D. E. (2001). Reasoning from uncertain premises: Effects of expertise
and conversational context. Thinking and Reasoning, 7, 367 – 390.
Strawson, P. F. (1952). Introduction to logical theory. London: Methuen.
Sweetser, E. E. (1990). From etymology to pragmatics. Cambridge, UK: Cambridge University
Press.
Thompson, V. A. (1994). Interpretational factors in conditional reasoning. Memory and
Cognition, 22, 742 – 758.
Thompson, V. A. (2000). The task-specific nature of domain-general reasoning. Cognition, 76,
209 – 268.
Thompson, V. A., Evans, J. St. B. T., & Handley, S. J. (2005). Persuading and dissuading by
conditional argument. Journal of Memory and Language, 53, 238 – 257.
Verstraete, J. C. (2005). Scalar quantity implicatures and the interpretation of modality
problems in the deontic domain. Journal of Pragmatics, 37, 1401 – 1418.
Wason, P. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal
of Experimental Psychology, 12, 129 – 140.
MODUS SHMOLLENS AND PRAGMATICS OF NEGATION 221

Wason, P. (1965). The contexts of plausible denial. Journal of Verbal Learning and Verbal
Behavior, 4, 7 – 11.
Wason, P. (1966). Reasoning. In B. M. Foss (Ed.), New horizons in psychology (pp. 106 – 137).
Harmandsworth, UK: Penguin.
Wason, P. (1972). In real life negatives are false. Logique et Analyse, 15, 17 – 38.
APPENDIX: MATERIALS USED IN THE EXPERIMENTS
Swedish Prof
E´milie and Fabrice are talking about one of their professors. [Generally
speaking, if a professor has a Swedish name, then she is a Swede.] [E´milie
tells Fabrice that] the professor is not a Swede.
Conclusion: The professor has a Swedish name?
Mick Jagger
Ge´raldine and Henri are listening to a record. [Generally speaking, if Mick
Jagger is singing on a record, then it is a Rolling Stones record.] [Ge´raldine
tells Henri that] this record is not a Rolling Stones record.
Conclusion: Mick Jagger is singing on this record?
Garlic soup
Carole and Didier are eating a soup. [Generally speaking, if a soup tastes
like garlic, then there is garlic in the soup.] [Carole tells Didier that] there is
no garlic in the soup.
Conclusion: The soup tastes like garlic?
Panther
Alice and Benjamin are looking at an animal in a zoo. [Generally speaking,
if an animal looks like a panther, then it is a panther.] [Alice tells Benjamin
that] this animal is not a panther.
Conclusion: The animal looks like a panther?
222 BONNEFON AND VILLEJOUBERT