Tense and Connective Constraints on the Expression of Causality 
Pascal Amsili 
TALANA, 
Universit6 Paris 7 
2, pl. Jussieu, case 7003 
F-75251 PARIS Cedex 05, France 
Pascal. Amsili@linguist. jussieu, fr 
and 
Corinne Rossari 
Universlt6 de Gen~ve, 
Facult6 des Lettres, dpt de Linguistique 
2, rue de Candolle, 
CH-1211 GENI~VE 4, Switzerland 
Corinne. Rossar i@lettres, unige, ch 
Abstract 
Starting from descriptions of French connectives 
(in particular "donc"---therefore), on the one 
hand, and aspectual properties of French tenses 
pass4 simple and imparfait on the other hand, 
we study in this paper how the two interact 
with respect to the expression of causality. It 
turns out that their interaction is not free. Some 
combinations are not acceptable, and we pro- 
pose an explanation for them. These results ap- 
ply straightforwardly to natural language gen- 
eration: given as input two events related by 
a cause relation, we can choose among vari- 
ous ways of presentation (the parameters being 
(i) the order, (ii) the connective, (iii) the tense) 
so that we are sure to express a cause relation, 
without generating either an incorrect discourse 
or an ambiguous one. 
1 Introduction 
The work reported in this paper aims at deter- 
mining which constraints hold on the interac- 
tion between the expression of causality (with 
or without connective) and aspectual properties 
of the eventualities and of the tenses used to ex- 
press them. As a matter of fact, it turns out 
that, at least in French, the choice of one of the 
two tenses pass4 simple (PS) or impar/ait (IMP) 
is not neutral with respect to the expression of 
causality, in particular realised by means of the 
connective "don c" (theref0re). 
It has been observed that even when con- 
cerned only with temporal localisation, it is not 
enough to characterize tenses if one do not take 
into account the effects of discourse relations be- 
tween eventualities 1: (1a-b) (Molendijk, 1996); 
it has also been observed that the use of the 
1We use the term eventuality to refer to either events, 
states or processes, as is traditional since (Bach, 1981). 
connective "donc" is itself subject to various ac- 
ceptability constraints (lc-d) (Jayez, 1998). 
(1) a. Paul attrapa une contravention. 
I1 roulait avec plaisir 
Paul got fined. He was driving with 
pleasure 2 
b. Paul attrapa une contravention. 
I1 roulait trop vite 
Paul got fined. He was driving too fast 
c. La branche cassa. 
Paul tombait donc dans le vide 
The branch broke. 
Paul was therefore falling down 
d. Sa premiere demande fut refus6e. 
I1 en r6digeait donc une autre 
His first application was refused. 
He was therefore writing another one 
Our objective in this paper is twofold: we 
want to study systematically the interaction 
between the various parameters we have men- 
tionned, in order to provide a general expla- 
nation for the acceptabilities that have been 
observed, and we also want these explanations 
be formulated in terms of "conditions of use", so 
that our results are exploitable for text gen- 
eration. As a matter of fact, the choice of an 
appropriate form to express a cause relation be- 
tween events has proved a non trivial problem 
(Danlos, 1987; Danlos, 1998). Two parameters 
have been identified as playing an important 
role: first, the order of presentation (cause be- 
fore consequence, or the contrary), and second, 
2The contrast between PS and IMP is only roughly par- 
allel to that between simple past and past progressive: 
e.g., the translation into French of a simple past can be 
either PS or IMP. We translate systematically IMP into 
past progressive, even when the glose does not have the 
same aspectuo-temporal properties as the French origi- 
nal. Similarly, "therefore" is only roughly equivalent to 
"done". 
48 
the presence (or absence) of a connective 3. The 
examples we deal with in this paper suggest that 
tenses, at least in French and in particular the 
choice between PS and IMP must also be taken 
into account. 
The assumptions we make for this work are 
the following. 
We assume the view on discourse adopted 
within the SRDT framework (Asher, 1993): in 
a coherent discourse, sentences are linked by 
discourse relations, which help finding anaphor 
antecedents, computing temporal localisations, 
etc. Here, we are concerned only with two dis- 
course relations, both involving causality. We 
call the first one result, as in (Lascarides and 
Asher, 1993), it holds between two sentences 
when the main eventuality of the first one is the 
cause of the main eventuality of the second one. 
We assume here a very open notion of causal- 
ity that we don't want to refine. 4 We call the 
other one explanation, it holds between two sen- 
tences when the cause is presented after its con- 
sequence, thus playing an explanation role for 
the first sentence. This configuration in inter- 
action with "donc" has been studied in (Rossari 
and Jayez, 1997) where it is called "causal ab- 
duction". 
We adopt as a basis for the description of 
IMP the proposal made in the DRT frame- 
work (Kamp and Rohrer, 1983; Kamp and 
Reyle, 1993), amended with proposals made in 
French literature, in particular concerning the 
anaphoric properties of this tense (Tasmowski- 
De Ryck, 1985; Vet and Molendijk, 1985; 
Molendijk, 1994). 
At last, we adopt the description of the con- 
nective "donc" which is elaborated, in terms of 
conditions of use and semantic effects, in (Jayez 
and Rossari, 1998). 
We start by considering discourses where a 
cause is presented after its consequence (i.e., an 
explanation discourse relation should hold). We 
observe that a PS-IMP sequence is sufficient to 
achieve the explanation effect, but that this se- 
quence is constrained by the type of causality 
3(Danlos, 1988) shows the influence of many others 
parameters, like the voice active vs. passive, the presence 
of a relative clause, etc. 
4For instance, we assume that causality holds be- 
tween a branch breaking and John's falling (direct), but 
also between Jean's repairing his car and his driving it 
(indirect). 
at stake. We also notice that connectives do not 
seem to interfere with tenses in this case (§ 2). 
We then examine discourses where the cause 
is presented before the consequence. In the ab- 
sence of connective, we observe that none of the 
acceptable forms automatically convey causality 
(§ 3.1). With the connective "donc", causality 
is imposed by the connective, but in its turn it 
brings new constraints (§ 3.2). For each set of 
examples, we provide a general explanation and 
draw conclusions for text generation. 
2 Consequence-Cause Configuration 
2.1 Data 
Even if a causality (the second sentence intro- 
ducing the cause of the first one) is pragmati- 
cally possible in all these examples, we observe 
that a sequence PS-PS imposes in French a tem- 
poral sequence interpretation: in all the exam- 
ples (3), the main eventuality of the second sen- 
tence is interpreted as temporally located after 
the one of the first sentence, and this is strictly 
incompatible with a causality, where cause must 
precede its effect. Notice that here Ps in French 
behaves differently from simple past in English. 5 
(3) a. Jean tomba. La branche cassa 
Jean fell. The branch broke 
b. Jean attrapa une contravention. 
Il roula trop vite 
Jean got fined. He drove too fast 
c. Marie cria. Jean lui cassa la figure 
Marie cried. Jean hit her 
d. Jean prit sa vulture. Il la r@para 
Jean took his car. He repaired it 
e. Jean se salit. Il r@para sa voiture 
Jean dirtied himsel£ He repaired his car 
Now, if one chooses, with the same order of 
presentation, the tense combination PS-IMP, the 
causality effect is easily achieved. This is the 
case for the examples (4). 
(4) a. Jean attrapa une contravention. 
I1 roulait trop vite 
Jean got a fine. He was driving too fast 
b. Marie cria. Jean lui cassait la figure 
Marie cried. Jean was hitting her 
5The translation of the ambiguous example (2a) (Las- 
carides and Asher, 1993) is not ambiguous in French 
where no causal interpretation is available (2b). 
(2) a. John fell. Max pushed him. 
b. Jean tomba. Max le poussa. 
49 
However, this choice is not always applicable, 
since it can give rise to unacceptable forms: (5) 
are either incorrect, or do not convey causality. 
(5) a. @ Jean tomba. La branche cassait 
Jean fell. The branch was breaking 
b. @ Jean prit sa voiture. Il la r6parait 
Jean took the car. He was repairing it 
The connective "donc" can be used in such 
configurations, without changing acceptability. 
The denoted relation in this case concerns both 
the epistemic level (attitudinal) and the descrip- 
tive level (propositional) (Jayez and Rossari, 
1998). We consider in this paper only uses 
of "donc" where the epistemic level does not 
change fondamentaly the relation. 6 
2.2 Discussion 
We think that these acceptabilities can be ex- 
plained if one takes into account two princi- 
ples: one concerns causality itself in connection 
with aspectuality, the other concerns the French 
IMP'S ability to act as an aspectual operator. 
2.2.1 Causality 
To account for the contrast between (4) and 
(5), we have to be more specific about the way 
causality can hold between eventualities. Let us 
assume el is the cause of e2. We can distinguish 
two cases: 
1. el has to be completed to be the cause of e2. 
For instance, the breaking of the branch has 
to be completed before Jean can fall; Jean's 
car has to be repaired before he can drive 
it. 
2. it is not necessary for el to be completed 
to be the cause of e2. For instance, starting 
to repair the car is enough to be the cause 
of one's getting dirty; driving too fast is 
enough to get a fine, independantly of the 
completion of el. 
We call the first case accomplished causality. 
Notice that this distinction is independant of the 
aspectual class of the verb describing the even- 
tuality. It is only a matter of world knowledge. 
6In this configuration, "car" (.for) is the non marked 
connective. Its introduction does not change notably the 
acceptability jugements, we leave the examination of its 
specific constraints for another study. 
2.2.2 IMP as an aspectual operator 
One of the most important properties of IMP 
is that it imposes an imperfective (durative, 
non accomplished) view on the eventuality (Vet, 
1980). The way this effect operates can be de- 
scribed the following way, assuming the usual 
partition of predicates into the four Vendler's 
(1967) aspectual classes. 
States, activities These eventualities, either 
homogenious (states) or not (activities), are 
non terminative, in the sense that they do 
not have a natural term (end) (e.g., to know 
the truth--state, to run--activity). Then 
IMP is entirely compatible, thus have no 
particular effect. 
Achievements, accomplishments These are 
characterised by the existence of a natu- 
ral term. The imperfective point of view 
brought by IMP imposes a change of point 
of view on the term of the eventuality. 
As for accomplishments, we can assume 
that they can be decomposed into several 
stages, according to (Moens and Steedman, 
1988): first a preparatory phase, second a 
culmination (or achievement) (we are not 
concerned here with the result state). We 
can then say that IMP refers only to the 
preparatory phase, so that the term of the 
eventuality loses all relevance. This ex- 
plains the so-called imperfective paradox: 
it is possible to use IMP even though the 
eventuality never reaches its term: 
(6) a. I1 traversait la rue quand la voiture 
l'a 6cras6 
He was crossing the street when the car 
hit him 
b. * I1 traversa la rue quand la voiture 
l'a 6cras6 
He crossed the street when the car 
hit him 
As for achievements, we can assume that 
they are reduced to a culmination. Then 
IMP can only be interpreted by stretching 
this culmination, transforming a fundamen- 
taly punctual event into a process or activ- 
ity. Then there is no more natural term for 
such a stretched event. 
2.2.3 Causality and aspect 
So, when we have a non accomplished causality, 
i.e., when it is possible to state the cause rela- 
50 
tion as soon as the eventuality has started, then 
IMP does not impose further constraint, and the 
sequence PS-IMP is always correct, and conveys 
the appropriate causality effect. This is the case 
for the examples (4, 7), where an explanation 
discourse relation is infered. 
(7) Jean se salit. I1 rfiparait sa voiture 
Jean got dirty. He was repairing his car 
On the contrary, if we have an accomplished 
causality, i.e. if the cause event has to be com- 
pleted to be a cause for the other event, then IMP 
is never possible, for even with terminative even- 
tualities (the branch breaking, fixing the car), it 
has the effect of blocking the terminativity, and 
a causal interpretation is no longer possible (5). 
The contrast (8) can thus be easily explained: 
in (8a), we have a lexically punctual event, made 
durative by the IMP. But going through a red 
light has to be completed to risk a fine; in (8b), 
we have an activity, and it is sufficient to have 
started it to risk a fine. 
(8) a. , Jean attrapa une contravention. 
I1 brfllait un feu rouge 
Jean got a fine. He was going through 
a red light 
b. Jean attrapa une contravention. 
I1 brfilait les feux rouges 
Jean got a fine. He was going through 
the red lights 
2.3 Application 
The consequences of the observations and the 
hypotheses made earlier, when it comes to text 
generation, are the following: 
If one wants to present two eventualities re- 
lated by a cause relation, so that the conse- 
quence is presented before the cause, leading to 
an explanation interpretation of the discourse, 
one should obey the following principles: 
1. A PS-PS combination is not appropriate. 
2. A PS-IMP combination conveys causality, 
provided that we have a non accomplished 
causality. Otherwise, the PS-IMP combina- 
tion is not valid. 
We should note again that these constraints 
are not lexical, in the sense that they do not 
rely on aspectual classes, but rather on world 
knowledge. 
3 Cause-Consequence Configuration 
Let us now turn to the other mode of presenta- 
tion, namely the one where cause is presented 
before its consequence. We first consider cases 
without connectives, and see that good accept- 
abilities go along with higher ambiguity: cor- 
rect example do not always convey causality 
(§ 3.1). Then we consider the use of the con- 
nective "donc", and observe that it changes the 
acceptabilities (§ 3.2). 
3.1 Without connective 
3.1.1 Data 
The first observation is that it is possible to use 
a PS-PS sequence. In the absence of other dis- 
course clues, such a sequence is interpreted in 
French as a temporal sequence relation. Such a 
temporal interpretation is compatible with, but 
of course does not necessary imply, a cause re- 
lation. 
(9) a. 
b. 
C. 
d. 
La branche cassa. I1 tomba dans le vide 
The branch broke. He fell down 
Paul vit sa demande rejet~e. 
IIen r~digea une autre 
Paul's application was rejected. 
He wrote an other one 
I1 rut nomm~ PDG. 
I1 contr61a tout le personnel 
He was appointed chairman. 
He had control over the whole staff 
I1 appuya sur la d~tente. Le coup partit. 
He pressed the trigger. The gun went off 
Changing the PS-PS sequence into a PS-IMP 
changes only marginally the acceptabilities, and 
the same observation as before holds: these dis- 
courses do not necessarily imply causality. 
(10) a. La branche cassa. 
I1 tombait duns le vide 
The branch broke. He was falling down 
b. Paul vit sa demande rejet~e. 
I1 en r~digeait une autre 
Paul's application was rejected. 
He was writing an other one 
c. I1 fut nomm~ PDG. 
I1 contr61ait tout le personnel 
He was appointed chairman. 
He was having control over the whole staff 
d. ? I1 appuya sur la d~tente. 
Le coup partait. 
He pressed the trigger. 
The gun was going off 
51 
For instance, (10b-c) can also be interpreted 
as background discourses, where the IMP of the 
second sentence is seen as introducing a back- 
ground situation holding before and after the 
event introduced in the first sentence. This in- 
terpretation, often given as the default one for 
IMP-PS sequences (Kamp and Rohrer, 1983), is 
nevertheless only available when world knowl- 
edge does not exclude it (10a). In any case, such 
an interpretation is incompatible with a causal 
interpretation. 
3.1.2 Discussion 
So it turns out that PS-IMP sequences can have 
in general two interpretations: one where the 
two events follow each other, and this interpre- 
tation is thus compatible with a causality inter- 
pretation, and another one where the eventual- 
ity described by the IMP sentence overlaps with 
the event given before. 
This can be explained if one assumes the op- 
eration of IMP as described in (Molendijk, 1994), 
in a DRT framework, itself inspired by (Reichen- 
bach, 1947). 
One of the features of IMP is to state the 
simultaneousness of the eventuality described 
with some reference point (henceforth Rpt), lo- 
cated in the past of the speech time. This oper- 
ation can be called anaphoric, since IMP needs 
some other point given by the context. This is 
clearly what happens with the background ef- 
fect. But it has also been shown, in particular 
by Tasmowski-De Ryck (1985), that there are 
some uses of IMP (called imparfait de rupture-- 
"breaking IMP") which are not strictly anaphoric, 
in the sense that the Rpt cannot be identified 
with any previously introduced event. Rather, 
it seems that such uses of IMP strongly entail the 
existence of an implicit Rpt, distinct from the 
events already introduced. It is also observed 
that this ability of IMP to bring with it a Rpt 
is constrained. In particular, there must be a 
way to connect this Rpt to the other eventual- 
ities of the discourse. Molendijk (1996) shows 
that this connection can be a causal relation. It 
has also been observed that an implicit Rpt is 
always temporally located after the last event 
introduced. So this is compatible with a causal- 
ity interpretation. 
3.1.3 Application 
From a text generation point of view, the obser- 
vations we have just made cannot be easily ex- 
ploited: obviously, in a Cause-Consequence con- 
figuration, all the tense combinations we have 
seen are not informative enough, and cannot be 
used, if one wants to guarantee that the concept 
of causality is conveyed by the discourse. 
It is thus necessary to be more explicit, for 
instance by adding a connective. This is what 
we are concerned with in the next section. 
So, if we leave apart the PS-PS sequence, what 
we have seen so far in § 2 is that the tense com- 
bination is sufficient to convey a causality rela- 
tion in Consequence-Cause configurations, and 
then the connectives do not impose further con- 
straints and do not change what is conveyed. 
The situation in this section (§ 3) is in a way 
symetrical: in a Cause-Consequence configura- 
tion, the tense configuration is not sufficient, so 
that adding a connective is necessary. But, as 
we see in the next section, there are further con- 
straints on the connectives. 
3.2 With the connective "doric" 
3.2.1 Data 
One can observe that "donc" is perfectly com- 
patible with PS-PS sequences like the ones in (9). 
What is more surprising is that adding "donc" 
to the PS-IMP sequence examples we have seen 
(10) clearly changes the acceptabilities: 
(11) a. ?? La branche cassa. I1 tombait donc 
dans le vide 
The branch broke. He was therefore falling 
down 
b. Paul vit sa demande rejet~e. IIen 
r~digeait doric une autre 
Paul's application was rejected. He was 
therefore writing another one 
c. I1 fut nomm~ PDG. I1 contr61ait donc 
tout le personnel 
He was appointed chairman. He was 
therefore having control over the whole staff 
d. ?? I1 appuya sur la d~tente. 
Le coup partait donc. 
He pressed the trigger. The gun was 
therefore going off 
The clearer contrast concerns cases where the 
second sentence contains an activity verb. In 
such cases, the introduction of"donc" leads sys- 
tematically to bad sentences. On the contrary, 
it seems that "donc" is always compatible with 
state and accomplishment verbs. 
As for achievements, it seems that the intro- 
duction of"donc" also yields bad sentences, but 
52 
it is worth noting that the simple sequence PS- 
IMP without connective is already slightly prob- 
lematic, as we have seen in (10d). We come back 
to this point later. 
3.2.2 Discussion 
We are not yet able to provide a completely elab- 
orated explanation for these observations. What 
we propose here is a list of possible answers, sug- 
gested by more fine-grained considerations on 
data. 
Note however that from the previous observa- 
tion we can draw the principle that we can gen- 
erate sentences in a Cause-Consequence configu- 
ration, with a PS-IMP sequence, and the connec- 
tive "doric" but the aspectual class of the verb 
has to be taken into account. It leads to accept- 
able sentences only with accomplishments and 
states. 
It is clear that aspectual classes play a role, 
which is not surprising, and this is the reason 
why all our example lists comprise each time 
one verb from each aspectual class. 
The most problematic contrast concerns the 
difference between activities and accomplish- 
ments. The connective "donc" seems to work 
very well with accomplishments and very bad 
with activities, even though accomplishments 
can be seen as composed of an activity fol- 
lowed by a culmination. One possible explana- 
tion could rely on the observation that the re- 
sult relation brought by "donc" holds not at the 
propositionnal level, not even at the aspectual 
(i.e., point of view on events), but rather at an 
attitudinal level (Rossari and Jayez, 1997). Be- 
sides, one can observe that what distinguishes 
activities and accomplishments is not the na- 
ture itself of the eventuality, but rather the fact 
that one expects/considers the culmination of it 
in one case and not in the other. So this can be 
seen as a difference of (propositional) attitude 
over the eventualities. We are presently working 
on the elaboration of a proposal based on this 
viewpoint. It is also worth observing that the 
temporal interval that lies between a cause and 
its consequence might play a role, as suggested 
by (Jayez, 1998), especially for this contrast be- 
tween activities and accomplishments. 
As for achievements, we have already noted 
that their compatibility with IMP is not entirely 
established, for reasons coming from the punc- 
tual nature of achievements. It is also worth 
noting that there is an affinity between achieve- 
ments and "imparfait de rupture" (Tasmowski- 
De Ryck, 1985). Of course, as suggested by 
its name, such use of IMP introduces a sort of 
break in the discourse, which is of course com- 
patible with causality, but might not be com- 
patible with the way "donc" operates, requiring 
a strong connection between two utterances. 
4 Conclusion 
Summary We summarize our observations in 
the table 1. We consider in this table all the 
possible configurations one has when the three 
following parameters vary. 
1. Order of presentation: el before e2 or the 
other way around (assuming el is the cause 
of ee). 
2. Presence of a connective "donc" or "car". 7 
3. Use of PS or IMP. 
Table 1: Ways of expressing "CAUSE(el, e2)" 
When D.R. How 
Always res e~ S. Donc e~ s 
exp e~ ~. Car 7 e~ S 
Ps e~S SHC e 1 . 
ntr e~ s. e~P 
Sometimes C1 res e~'. Donc e~ P 
C2 exp e~ ~. ( CarT/¢ ) e~ MP 
Never e~ M". (Donc / I~ ) e~ ~ 
Ps e~S e.~. 
e~ p. (Car 7/0)e~ ~ 
Constraints 
CI: e2 : state or accomplishment 
C2: non accomplished causality 
Among the combinations, some are always 
possible (which does not mean they always con- 
vey causality), some are never possible, that 
is, either uninterpretable or incompatible with 
causality. Some are sometimes possible, depend- 
ing on various constraints as shown in this pa- 
per. Notice that we mention in this table some 
configurations we have not considered so far, 
namely configurations with an IMP-PS sequence. 
r As we have already said, we are only concerned in 
this paper with "donc" and mention "car" only for the 
sake of completeness. 
53 
We mention them here only for the sake of com- 
pleteness, since they can never be used to ex- 
press causality. 
The second column of the table gives the dis- 
course relation associated with each configura- 
tion. In some cases, it is a cause relation, ei- 
ther in one direction (result-res) or in the other 
(explanation-exp). The other cases are compat- 
ible with a cause relation, without conveying it, 
which is noted in the table as "suc" (for tempo- 
ral succession) or "ntr" (neutral-for ambiguous 
cases between background or temporal succes- 
sion). 
Conclusion This paper shows that the inter- 
action of constraints coming from tenses and 
connecti.ves is rather delicate to characterize, 
even in the limited domain of the expression of 
causality. It also shows, however, that it is pos- 
sible to draw from the linguistic characterisation 
of these enough principles to be able to generate 
discourses conveying causality with good guar- 
anties on the achieved effect, and control over 
the influence of tenses often neglected in this 
respect. 
We are presently studying the treatment of 
other connectives, and the extension to other 
tenses. 
Acknowledgments 
We wish to thank Laurent Roussarie, as well as 
the anonymous reviewers for their helpful com- 
ments on earlier versions of this paper. 

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