Discourse topic

40 Pages·0.2 MB·English

by  Asher N.

Discourse topic
NICHOLAS ASHER
1. Introduction
Discourse Topic is a familiar but also elusive concept. Any competent
speaker or writer knows that a coherent discourse has bits that have a
common theme and these common themes typically link together to ex-
pand upon a larger theme. This is how we learn to write paragraphs (the
leadsentence), essays,chaptersand even books.
Researchers like van Kuppevelt (1995) have thought that discourse
topics must be an intrinsic feature of the logical form of a coherent dis-
course; they are organizing principles of discourse interpretation. SDRT,
theformaltheoryofdiscourseinterpretationthatIhaveworkedon,hasa
much more limited view of discourse topic; discourse topic plays an im-
portantroleinconnectionwithcertaindiscourserelationslikeNarration.
Other discourse relations, in particular those that exploit the logical or
semantic structure of the discourse constituents they relate like Parallel
and Contrast (Asher 1993, Asher and Lascarides 2003), have something
similar to a topic as an intrinsic part of their semantics; Parallel holds
between two constituents only if there is a common theme of those con-
stituents; Contrast holds only if there are contrasting themes. Themes
are relatively straightforward to define (though the details are somewhat
messy–seeAsher(1993),orAsher,HardtandBusquets(1997)foracon-
siderably improved account. Themes are unlike discourse topics for Nar-
ration, however, inthattheymust reflectasfully aspossiblethecommon
logical structure of the two Parallel or Contrasting constituents. Fur-
ther, while they are an essential part of the semantics of these relations,
they are not themselves needed as constituents in logical form. Discourse
topics for Narration inSDRT, on the other hand, should summarizeand
TheoreticalLinguistics30(2004),163–201 0301–4428/04/0030–0163
6WalterdeGruyter
164 Nicholas Asher
abstractawayfromthelogicalstructureoftheconstituentstheyaretopics
of. For a variety of purposes they are also needed as constituents in the
discourse structure. The discourse relation of Alternation, for which the
presence of disjunction is a good but defeasible indication, also requires
a particular notion of topic for its semantics, and it is one that’s di¤erent
from thatforNarration.
Developping a formal theory of discourse topic has proved di‰cult.
One reason is that, as I’ll demonstrate here, the notion of topic is not a
homogeneous one but varies depending on the discourse relations used –
viz., on the discourse context. But even for a particular notion of dis-
course topic like that for Narration, it has proved di‰cult to develop an
account in which a coherent discourse features a topic that we can con-
struct as interpretation proceeds incrementally. We don’t have a satisfac-
tory account of such a process, which may indeed be very complicated –
clearly more complicated than recognizing whether some extant segment
functionsasadiscoursetopic toanotherdiscourseconstituent.The prob-
lemforatheoryofdiscourseinterpretationevenlikeSDRTinwhichdis-
course topics play a limited role is that if there isn’t any e¤ective way of
constructingsuchtopicsorrecognizingthem,thenthereisn’tanye¤ective
way of fully specifying a logical form for a discourse. Although SDRT
limitstherelevanceofdiscoursetopicandallowsunderspecificationinde-
scriptionsoflogicalform(topicsthusmightoftenremainunderspecified),
it’s still an embarrassment not to have any way of making sense of topic
construction and a fortiori the phenomena that the introduction of dis-
course topicwas designed to dealwith.
Inordertogetabettergripondiscoursetopics,weneedtounderstand
better the information sources in language that a¤ect discourse topic.
There are intriguing connections between the notion of contrastive topic,
sentence topic and discourse topic. In this paper I’ll concentrate largely
oncontrastivetopic’s contributionto discoursetopic. Thoughnot always
present,contrastivetopicaspartoftheinformationstructuregivenbyin-
tonation furnishes an important source of information about discourse
topic, as Beyssade and Marandin (2002) and Grabski (2002) have argued
(see also von Heusinger 2001). I want first to pursue this line of thinking
by beginning with Bu¨ring’s influential work in this area. Combining
van Kuppevelt’s notion of discourse topic as a question and Bu¨ring’s
work on contrastive topic leads to an attractive theory of the interaction
Discoursetopic 165
between contrastive topic and discourse topic.1 But I will argue that the
pressures on this account and on what we want to do with discourse
makeitultimatelyunsustainable.I’lldevelopnextanaccountofAlterna-
tionwithavanKuppeveltliketopicbutinwhichthelinkbetweensenten-
tialtopicanddiscoursetopicplayslittlerole.IthenlookattopicforNar-
ration and what it’s supposed to do. I’ll then give another account of the
relationbetweencontrastivetopicandotherinformationstructureindica-
torsanddiscourse topics for Narration.
2. Contrastive topic
Contrastive topic is grammatically marked in Hungarian, Korean,
Chinese, and other languages, while it is typically intonationally marked
in French, German and English. There are sentences that don’t have any
contrastive topic in them, at least in English, and I suspect in most other
languages. The literature on the subject of sentence topic is voluminous,
and I can’t do it justice here. Instead what I will do is concentrate on
just one, very clear and influential account of some ways of indicating
contrastive topic. That’s Daniel Bu¨ring’s account of the LþH(cid:1) tone or
‘‘hat contour’’sentence topic.
Bu¨ring’s notes an interesting interaction between this intonation and
felicitous responses to questions thatdon’t count as answers.
(1) a. Did John buy that book?
b. YES, John bought thatbook.
c. FRED wouldn’t buy thatbook.
d. # Fred wouldn’t buy that book.
e. # JOHNboughtthat book.
The special intonation contour (in German LþH(cid:1), in English
LþH(cid:1)LH%) is needed to make the response in (1b,c) felicitous. Bu¨ring
provides the following generalization: assertion A is a felicitous answer
to a question Q only if Q is one of the elements in the topic meaning of
1 Bu¨ring(1995)calledthephenomenonsentencetopic,butinrecentworkhehasadopted
thecontrastivetopicterminology.
166 Nicholas Asher
A, where a question Q is identical to the focus value of an assertion, and
thetopicvalueofA¼thesetofsetsofpropositionscorrespondingtothe
focus values for A with various alternatives substituted in for the topic’s
ordinary semantic value. In (1b), the topic value¼ffocus valueg and the
relevantfocusvalueisthequestion.Ontheotherhand,thetopicvalueof
(1d) is also identical to the singleton of its focus value which is disjoint
fromthesingletonsetofthequestion in(1a).Bu¨ring’sgeneralizationcor-
rectly predicts that (1d) is infelicitous. On other hand, (1c) is felicitous
since the topic value contains many questions, one of them being the se-
mantic value of (1a). Nowin order to account for the bizarreness of (1e),
we have to postulate a contrastive element to the intonational pattern, or
contrastivetopicmoregenerally:thefocusvalueofasentencewithacon-
trastive topic must not be the question itself, but a di¤erent question. Or
in other words, the ordinary semantic value must be a direct answer to a
di¤erentquestion than theone at issue.
The account carries over nicely to examples with two intonationally
prominent peaks, a hat contour and a standard H(cid:1) intonation that typi-
cally marks focus thatfills inthevalue of the WH bound variable.
(2) a. Whatdid you buy at the 59th bridge?
b. Auf der NEUNund fu¨nfzigsten Strasse habe ich [SCHUHE]
gekauft.
(3) a. Whatdid thepopstars wear?
b. The FEMALE popstarswore CAFTANS.
(4) a. Whatdid thepopstars wear?
b. The female popstars wore CAFTANS.
(5) a. Whatbook wouldFritzbuy?
b. ICH wu¨rde das HOTel New HAMPshire kaufen.
In (3b) the topic contains the following questions: What did the female
popstars wear? What did the male popstars wear? What did the male or fe-
male popstars wear?. Bu¨ring’s criterion makes this question answer pair
felicitous, whereas (4a–b) does not meet his test and is infelicitous.
If discourse topics were questions (van Kuppevelt 1995), then Bu¨ring’s
account yields a natural relation between sentence topic and discourse
topic. Contrastive topic values should contain the discourse topic of the
sentence. The ordinary semantic value of the sentence should serve as a
Discoursetopic 167
partial answer to the discourse topic question. As discourse proceeds, the
discourse topic should get ultimately resolved.
(6) a. Discourse topic: What were the popstars wearing?
b. The FEMALE popstarswore CAFTANS
c. Residual Discourse Topic: What were the male popstars
wearing?
One worry with this very nice picture is how do the discourse topic
questionsget generated?Consider for instance (7):
(7) a. The popstars were outlandishlydressed.
b. The FEMALE popstarswore CAFTANS.
c. The MALE popstarswore leather MOTORcycle outfits.
The first sentence of (7) in an intuitive sense gives the topic that the next
two sentences elaborate on. But on the Bu¨ring-van Kuppevelt picture,
each sentence contains the discourse topic question, What were the pop-
stars wearing? as part of its topic value; they also have a contrastive ele-
ment, in that they must be direct answers to a di¤erent subquestion of
the global discourse topic from the previous subtopic. Each CT marked
sentence o¤ers a partial answer to the global discourse topic by answer-
ing di¤erent subquestions. The Elaboration then proceeds by narrowing
down the discoursetopic and then answering the question completely.
The discourse topic, or DT, question generated for (7) is natural
enoughinthiscontext,butthereisnomechanismprovidedforextracting
such questions from the context. It is true that each sentence contains
the discourse topic question, What were the popstars wearing? as part of
its topic value, but they also contain infinitely many other questions that
arecompletelyunsuitableasDTs,especiallyifwetakethehatcontourto
go over the entire DP,which we need to handle exampleslike
(8) a. What were therockstars wearing?
b. ONE rockstar was wearing aTUTU
c. ANOTHERwas wearing a green CAFTAN
And the tone’s stretch over the whole DP gets us lots of bad questions,
because we are then free to replace the whole DP with any other DP,
since the set of alternatives for topic value has no constraints other than
matching thetopicelement in logicaltype.
168 Nicholas Asher
(9) a. Whatwere the non-rockstars wearing?
b. Whatwas Dick Cheneywearing?
These are not good DTs for the discourse. This account doesn’t capture
the link between DTs and CTs to be discourse topics and contrastive
topics.TheCTsentencesarenotappropriateanswerstoarbitrarychoices
of DT even when backgrounds are held constant. Furthermore, how do
we rule out as a continuation in (7):
(10) The NON popstars wore MINISKIRTS.
What is missing in this account is that the ordinary extensions of the ST
phrasesshould be partof the extensions of some element in the DT.
Anotherworryhastodowithverynaturalcontinuationsof(7)likethe
following:
(70) a. The popstars were outlandishly dressed.
b. The FEMALE popstars wore CAFTANS.
c. The MALE popstars wore leather MOTORcycle outfits.
d. They had helmets too, goggles and strangeboots.
We would suppose that the discourse topic has already by (7c) been ex-
hausted.Inwhichcase,wedon’tknowhowtofitintheextendedelabora-
tion. Nevertheless it plainly is part of the Elaboration and is perfectly fe-
licitous. (70d) is an example of a sentence with no intonationally marked
sententialtopic.
There’s a simple fix to the problems I’ve brought up for the Bu¨ring
theory. But I don’t know how to state the fix in the terms of an ‘‘alterna-
tives theory’’. The problems I have noted go away in the case the con-
trastive topic marked constituents are DPs that introduce discourse refer-
ents, if we require in addition to Bu¨ring’s constraint that the values
of those discourse referents be a part of some plural entity in discourse
topic.Thissimplefix,however,cannotbeexpressedinalternativeseman-
ticsbecausewecannotrecoverthesevaluesfromthesemanticvalues.One
might conceivablycomplicate alternative semanticsin someway to make
it dynamic, but it seems easier to develop this idea within a structured
meanings or representational approach, which is what I shall do in the
penultimate section.
The contribution of CT really depends on the discourse context, and
that is something totally missing from the alternatives story. Beyssade
Discoursetopic 169
and Marandin (2002) argue that Bu¨ring’s analysis of the role of sentence
topic inquestion answer pairs sometimesgoeswrong:
(11) a. A: Qui a e´te´ invite´?
b. B: La POSte est en gre`ve.
c. A: Ok, on annule.
AccordingtoBeyssadeandMarandin,B’sresponsehasatopicaccentbut
noneofthequestionsinitstopicvalueincludesthequestionin(11a).For
Beyssadeand Marandin,thetopicalaccentmarksitsclauseassomething
contrastiveorenumerative(whichisone ofthecluesforan Elaboration).
This is compatible with Bu¨ring’s account in that topic accent on a re-
sponse means that there is more to say about answering the question
(and so it marks a partial answer) but the picture is too simple. The re-
sponse by B in (11) constitutes an indirect answer (the WH question with
it forms an Indirect Question-Answer Pair (IQAP) pair), which is defined
in SDRT as providing enough information to infer an answer, which in
this case is no one. The CT (if it is the same sort of CT that Bu¨ring dis-
cusses from German data) has some sort of contrastive force in that WH
questionsatleastimplicateifnotpresupposethattheWHboundvariable
has a satisfier. There is something similar here to Bu¨ring’s idea; the CT
marked response contrasts with, let’s call it, an ‘‘expectation’’ that the
WH question has a positive answer, but it also itself contributes material
toan answer.
This ‘‘something common to DT something di¤erent’’ quality is also
part of other uses of a topic or CT like tone in French, as Beyssade and
Marandin remark. Here is another one of their puzzling examples, in
which the CT is naturally read as having something to do with Jean-
Marie. The contrast implies that one might expect her to be happy (there
isa natural focus accenton contente).
(12) a. A: Jean-Marieest arrive´
b. B: Oui, BERnadette n’est pas contente.
CT accents in English closely resemble another sort of intonation pat-
tern noticed by Mark Steedman.
(13) a. A: Fred doesn’t like operas (standard contour).
b. B:HelikesMUSICALS(withtheLþH(cid:1)LH%contour,notthe
standard focus accent)
170 Nicholas Asher
(14) a. A: Fred doesn’thavea girlfriend.
b. B: He’s been going to NEW YORK alot lately.
This tone, like the CTaccent, indicatessomerelation to thetopic, but an
indirect one. The standard Bu¨ring account could work for (13) if we
could generate the discourse topic question, What does Fred like?, from
the context. But I don’t see a principled way of doing that. More impor-
tantly, in (13) and (14), the intonation pattern indicates a disagreement:
e.g.,BiscounteringA’sclaimwithsomeevidencethatmightsuggestthat
Fred does have a girlfriend in New York. But it is responding, like (13),
tothepreviousassertion;itisaboutthetopicofwhetherinonecaseFred
likes operas or Fred has a girlfriend in the other, and it also shows that
the interpretation of the tone itself is very much subject to discourse con-
text,thoughthedetailsoftheinteractionremaintobeworkedout.Within
theframeworkofSDRTwecanbemuchmorespecific:Ifyouhaveadis-
course constituent a whose prosody contains a hat contour and if you
attach a to some constituent b in l and the component of a marked by
the contour is part of an entity mentioned in g where Elaborationðg;lÞ,
then you should so attach and you will infer Elaboration ðg;aÞ making
theappropriatelinkbetweenDTandCT(detailstofollowbelow).Here’s
agraph of the discourse configurationafter the attachment of a.
g
(cid:1)
(cid:1) Elaboration
(cid:1)
l
b------------------a
On the other hand, if you’re attaching a,which has a hat contour, to b
and Autters a and B utters b,and thereisnoobvious DT, then you take
theDTtobeaandthenthetonehasthemeaning thatb isabout abutit
contrastswithitinaquiteparticularway:itisadefeasibleindicationthat
Counterevidenceða;bÞ.
3. Topics for alternation
CTprovidesanimportantsourceofinformationaboutDTwithinElabo-
rations.ButDTsdon’tonlyoccurwhenthereareCTs.Furthermore,DTs
Discoursetopic 171
areimportant to other discourse relations. Alternations, for instance, like
Parallel and Contrast, incorporate a notion of topic into their semantics
thatbearssomeresemblancetothenotionofdiscoursetopicofourprevi-
ousaccount.Butwithalternations,contrastivetopicsplayaninsignificant
role. Topics for alternations arise in a di¤erent way; instead of CT, the
presence of disjunctions playsa key feature.
Topicsforalternationsplayanimportantrolewithrespecttoanaphoric
availability (Ohlman and Clarady 2000). There are notorious di‰culties
with anaphoric links inalternations,somethingfirstnoticed by Partee.
(15) a. Either there’s no bathroom in this house or it’s in a funny
place.
b. EitherJonesdoesn’townaPorsche,orhekeepsithiddeninhis
garage.
c. Either there are few good restaurants in this city or we’re not
lookingin the right place for them.
Ohlman and Clarady argue that (15) involve some sort of problem or
puzzle; there’s the problem of where a bathroom is or whether Jones has
a Porsche or not given certain evidence. Such topics suitably expressed
would su‰ce to solve the troublesome anaphors in these bathroom sen-
tences. If (15a) has as a topic the question, Where’s the bathroom?, then
we could use the presupposition of that question (namely that there is a
bathroom) to get an antecedent for the pronoun in the second disjunct.
In other words, we might have the following structurein SDRT.
p
0
p ;p ;p00
p 1
p :?lu x isin u
1
p :bx bathrmðxÞ
p
(15a0) Backgroundpðp ;p Þ
p 1
p : Topicðp ;p00Þ
0 1
p ;p ;p0
2 3
p00: p :K ;p :K ,
2 p2 3 p3
Alternationðp ;p Þ
2 5
172 Nicholas Asher
In case such structures are not familiar, such discourse structures consist
of a set of labels for discourse constituents fp;p ;p ;...g and an assign-
0 1
ment of formulas to labels – these formulas include relational predica-
tions on labels, as well as formulas that describe the contents of basic
constituents (this is graphically represented by the p:K where K is a dy-
namic semantic formula here or a DRS in other articles and books on
SDRT). The labels p labels a particular type of constituent – in this
p
caseapresupposition,whichmustattachasthefirstargumentofapartic-
ularkindofBackgroundrelation,whichI’llcallhereBackgroundp.There
are two sorts of discourse relations, those that push the discourse struc-
ture down (Foreground Background Pair, Elaboration, Elaboration ),
ct
subordinatingrelationsandthosethatpushthestructurefromlefttoright
(Narration),coordinatingrelations.A‘‘right-frontier’’ruleforattachment
tellsusthatunlesscertaintextualcluesaregiven(Asher1993),newinfor-
mation must either attach to the last entered constituent b in a discourse
structure or to some constituent g such that ðb;gÞ is in the transitive
closure of the subordination relation. This right frontier constraint also
a¤ects anaphora resolution: an anaphor may find an antecedent only in
a constituent that is on the right frontier of the SDRS graph in the sense
already expressed.
Note that x is accessible in p and available to the pronoun condition
0
z¼? in K , if we assume that Topic is a subordinating relation. Fur-
p5
ther, this means that the input assignments to K already have assigned
p1
a value to x and so even though questions might be tests, a value for this
variablewillbeavailableonanyoutputfrom K .The situationchanges,
p1
however, if we have asa topic isthere abathroom?.For now the variable
introduced for the bathroom is within the scope of the question operator
and if questions are tests with respect to dynamic assignments, as seems
reasonable (Asher and Lascarides 2003), then we no longer can bind
the anaphor in the second disjunct. In any case, however, it feels wrong
to have the presupposition of the Wh question outside the scope of
the second disjunct, because it renders the first disjunct moot, and that
should be disallowed on broadly Gricean reasons. If this is right, then
our simple solution to the anaphoric problem involving discourse topics
won’t do.
While there are lots of other potential solutions to the bathroom sen-
tences, there are still good reasons for thinking that some sort of dis-