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<Paper uid="P87-1021">
  <Title>THE INTERPRETATION OF TENSE IN DISCOURSE</Title>
  <Section position="3" start_page="0" end_page="149" type="intro">
    <SectionTitle>
1. Introduction
</SectionTitle>
    <Paragraph position="0"> My basic premise is that in processing a narrative text, a listener is building up a representation of the speaker's view of the events and situations being described and of their relationship to one another. This representation, which I will call an eventJsituatlon structure or e/s structure, reflects the listener's best effort at interpreting the speaker's ordering of those events and situations in time and space. The listener's problem can therefore be viewed as that of establishing where in the evolving els structure to attach the event or situation described in the next clause. My claim is that the discourse interpretation of tense contributes to the solution of this problem.</Paragraph>
    <Paragraph position="1"> This work on the discourse interpretation of tense is being carried out in the context of a larger enterprise whose goal is an account of explicit anaphoric reference to events and situations, as in Example 1.</Paragraph>
    <Paragraph position="2"> Example 1 It's always been presumed that when the glaciers receded, the area got very hot. The Folsum men couldn't adapt, and they died out. That's what's supposed to have happened./t's the textbook dogma.</Paragraph>
    <Paragraph position="3"> But it's wrong. They were human and smart. They adapted their weapons and culture, and they survived.</Paragraph>
    <Paragraph position="4"> Example 1 shows that one may refer anaphorically to structured entities built up through multiple clauses. Thus an account of how clauses arrange themselves into structures is necessary to an account of event reference. 2 IThis work was papally supported by ARO grant DAA29-84og-0027, NSF grant MCS-8219116-CER, and DARPA grant N00014-85-K-0018 to the University of Pennsylvania, and by DARPA grant N00014-aS.-C-0012 to UNISYS.</Paragraph>
    <Paragraph position="5"> =Other parts of ~e entemrise include a ganeraJ mechanism for individuating composite entities made up of ones separately introduced I20, 21J and a representation for events that aJlow for anaphoric reference to both particular events and situations and to abstractions thereof \[16\], In this paper, I will relate the problem of building up an e/s structure to what has been described as the anaphoric property of tense \[7, 11, 6, 1, 12\] and of relative temporal adverbials\[18\]. Anaphora are expressions whose specification is context-dependent. Tense and relative temporal adverbials, I interpret as specifying positions in an evolving els structure. My view of their anaphoric nature is that the particular positions they can specify depend on the current context. And the current context only makes a few positions accessible. (This I will claim to be in contrast with the ability of temporal subordinate clauses and noun phrases (NPs) to direct the listener to any position in the evolving structure.) The paper is organized as follows: In Section 2, I discuss tense as an anaphoric device. Previous work in this area has discussed how tense is anaphoric, claiming as well that it is like a pronoun. While agreeing as to the source of the anaphoric character of tense, I do not think the analogy with pronouns has been productive. In contrast, I discuss what I believe to be a more productive analogy between tense and definite noun phrases.</Paragraph>
    <Paragraph position="6"> Previous work has focussed on the interpretation of tensed clauses in simple linear narratives (i.e., narratives in which the order of underlying events directly corresponds to their order of presentation). 3 Here the most perplexing question involves when the next clause in a sequence is interpreted as an event or sequence coincident with the previous one and when, as following the previous one \[4, 6, 12\]. In Section 3, I show that if one moves beyond simple linear narratives, there are more options. In terms of the framework proposed here, there may be more than one position in the evolving e/s structure which can provide a context for the interpretation of tense. Hence there may be more than one position in els structure which tense can specify and which the new event or situation can attach to.</Paragraph>
    <Paragraph position="7"> To model the possible contexts, I introduce a discourse-level focussing mechanism - temporal focus or TF - similar to that proposed for interpreting pronouns and definite NPs \[17\]. I give examples to show that change of TF is intimately bound up with narrative structure. To keep track of and predict its movement, I propose a set of focus heuristics: one Focus Maintenance Heuristic, predicting regular movement forward, two Embedded Discourse Heuristics for stacking the focus and embarking on an embedded narrative, and one Focus Resumption ZAnother persOn currently addressing the interpretation of tense and aspect in more complex narratives is Nakhimovsky I9, 10\]. Though we are addressing somewhat different issues, his approach seems very compatible with this one.</Paragraph>
    <Paragraph position="8">  Heuristic for returning and resuming the current narrative. The need for each of these is shown by example.</Paragraph>
    <Paragraph position="9"> In Section 4, I show that relative temporal adverbials display the same anaphoric property as simple tense.</Paragraph>
    <Paragraph position="10"> That the interpretation of tense should be entwined with discourse structure in this way should not come as a surprise, as a similar thing has been found true of other discourse anaphora \[5\].</Paragraph>
    <Paragraph position="11"> 2. Tense as Anaphor Tense does not seem prima facie anaphoric: an isolated sentence like &amp;quot;John went to bed&amp;quot; or &amp;quot;1 met a man who looked like a basset hound = appears to make sense without previously establishing when it happened. On the other hand, if some time or event is established by the context, tense will invariably be interpreted with respect to it, as in: Example 2 After he finished his chores, John went to bed.</Paragraph>
    <Paragraph position="12"> John partied until 3arn. He came home and went to bed.</Paragraph>
    <Paragraph position="13"> In each case, John's going to bed is linked to an explictly mentioned time or event. This linkage is the anaphoric property of tense that previous authors have described.</Paragraph>
    <Paragraph position="14"> Hinrichs\[6\] and Bauerle\[1\], following McCawley \[7\] and Partee \[11\], showed that it is not tense per se that is interpreted anaphorically, but that part of tense called by Reichenbach \[14\] reference time. 4 According to Reichenbach, the interpretation of tense requires three notions: speech time (ST), event time lET), and reference time (RT). RT is the time from which the event/situation described in the sentence is viewed. It may be the same as ST, as in present perfect: ET&lt;RT=ST John has climbed Aconcagua and Mt. McKinley.</Paragraph>
    <Paragraph position="15"> simple presenti ET=RT=ST John is in the lounge.</Paragraph>
    <Paragraph position="16"> the same as El', as in simple past: ET=RT&lt;ST John climbed Aconcagua.</Paragraph>
    <Paragraph position="17"> simple future: ST&lt;ET=RT John will climb Aconcagua.</Paragraph>
    <Paragraph position="18"> in between ET and ST, as in past perfect: ET&lt;RT&lt;ST John had climbed Aconcagua.</Paragraph>
    <Paragraph position="19"> or following both El&amp;quot; and ST (looking bac~ to them), as in f.uture perfect: ST&lt;ET&lt;RT John will have climbed Mt. McKinley.</Paragraph>
    <Paragraph position="20"> That it is RT that it is interpreted anaphorically, and not either El&amp;quot; or tense as a whole can be seen by considering Example 3.</Paragraph>
    <Paragraph position="21"> .Example 3 John went to the hospital.</Paragraph>
    <Paragraph position="22"> He had twisted his ankle on a patch of ice.</Paragraph>
    <Paragraph position="23"> It is not the El&amp;quot; of John's twisting his ankle that is interpreted anaphorically with respect to his going to the hospital. Rather, it is the RT of the second clause: its ET is interpreted as prior to that because the clause is in the past perfect tense (see above).</Paragraph>
    <Paragraph position="24"> Having said that it is the RT of tense whose interpretation is anaphoric, the next question to ask is what kind of anaphoric behavior it evinces. In previous work, tense is claimed to behave like a pronoun. Partee \[12\] makes the strongest case, claiming that pronouns and tense display the same range of antecedent-anaphor linkages:</Paragraph>
    <Section position="1" start_page="147" end_page="147" type="sub_section">
      <SectionTitle>
Oeictic Antecedents
</SectionTitle>
      <Paragraph position="0"> pro: She left reel (said by a man crying on the stoop) s tense: I left the oven onl (said by a man to his wife in the car)</Paragraph>
    </Section>
    <Section position="2" start_page="147" end_page="147" type="sub_section">
      <SectionTitle>
Indefinite Antecedents
</SectionTitle>
      <Paragraph position="0"> pro: I bought a banana. I took it home with me.</Paragraph>
      <Paragraph position="1"> tense: I bought a banana. I took it home with me.</Paragraph>
      <Paragraph position="2"> &lt;1 took it home after I bought it.&gt;</Paragraph>
    </Section>
    <Section position="3" start_page="147" end_page="147" type="sub_section">
      <SectionTitle>
Bound Variables
</SectionTitle>
      <Paragraph position="0"> pro: Every man thinks he is a genius.</Paragraph>
      <Paragraph position="1"> tense: Whenever Mary phoned, Sam was asleep.</Paragraph>
      <Paragraph position="2"> &lt;Mary phoned at time t, Sam was asleep at t&gt;</Paragraph>
    </Section>
    <Section position="4" start_page="147" end_page="148" type="sub_section">
      <SectionTitle>
Donkey Sentences
</SectionTitle>
      <Paragraph position="0"> pro: Every man who owns a donkey beats it.</Paragraph>
      <Paragraph position="1"> tense: Whenever Mary phoned on a Friday, Sam was asleep.</Paragraph>
      <Paragraph position="2"> &lt;Mary phoned at time t on a Friday, Sam was asleep at t on that Friday&gt; Because of this similarity, Partee and others have claimed that tense is like a pronoun. Their account of how time is then seen to advance in simple linear narratives is designed, in part, to get around the problem that while pronouns coospecify with their antecedents, the RT of clause N cannot just co-specify the same time as the previous clause \[6, 12, 4\].</Paragraph>
      <Paragraph position="3"> There is another option though: one can draw an analogy between tense and definite NPs, which are also anaphoric. Support for this analogy is that, like a definite 4Hinrichs' work is discussed as well in \[12l.</Paragraph>
      <Paragraph position="4"> Sl believe thai the deictic use of pronouns is infelicitous. In this example, the speakeC/ is dis~'aught and making no attemp( to be cooperauve. It happens. But that doesn't mean thai pronouns have deictic antecedents. I include the example here because it is part of Partee's argument.  NP, tense can cause the listener to create something new. With a definite NP, that something new is a new discourse entity \[19\]. With tense, I will say for now that it is a new time at which the event or situation is interpreted as ocouring, s If one looks at texts other than simple linear narratives, this ability becomes clear, as the following simple example shows: Example 4 I was at Mary's house yesterday.</Paragraph>
      <Paragraph position="5"> We talked about her brother.</Paragraph>
      <Paragraph position="6"> He spent 5 weeks in Alaska with two fdends.</Paragraph>
      <Paragraph position="7"> Together, they made a successful assault on Denali.</Paragraph>
      <Paragraph position="8"> Mary was very proud of him.</Paragraph>
      <Paragraph position="9"> The event of Mary's brother spending five weeks in Alaska is not interpreted as occurring either coincident with or after the event of my conversation with Mary. Rather, the events corresponding to the embedded narrative in the third and fourth clause are interpreted at a different spatio-temporal location than the conversation. That it is before the conversation is a matter of world knowledge. In the els structure for the whole narrative, the tense of the third clause would set up a new position for the events of the embedded narrative, ordered prior to the current position, to site these events.</Paragraph>
      <Paragraph position="10"> The claimed analogy of tense with pronouns is based on the similarity in antecedent-anaphor linkages they display. But notice that definite NPs can display the same linkages in two different ways: (1) the definite NP can co-specify with its antecedent, as in the a. examples below, and (2) the definite NP can specify a new entity that is 'strongly' associated with the antecedent and is unique by virtue of that association, as in the b. examples below 7</Paragraph>
    </Section>
    <Section position="5" start_page="148" end_page="148" type="sub_section">
      <SectionTitle>
Deictic Antecedents
</SectionTitle>
      <Paragraph position="0"> The car won't startl (said by a man crying on the stoop)</Paragraph>
    </Section>
    <Section position="6" start_page="148" end_page="148" type="sub_section">
      <SectionTitle>
Indefinite Antecedents
</SectionTitle>
      <Paragraph position="0"> a. I picked up a banana. Up close, I noticed the banana was too green to eat.</Paragraph>
      <Paragraph position="1"> b. I picked up a banana. The skin was all brown. Bound Variables a. Next to each car, the owner of the carwas sleeping soundly.</Paragraph>
      <Paragraph position="2"> b. In each car, the engine was idling quietly.</Paragraph>
    </Section>
    <Section position="7" start_page="148" end_page="149" type="sub_section">
      <SectionTitle>
Donkey Sentences
</SectionTitle>
      <Paragraph position="0"> a. Everyone who wants a car must fix the car himself.</Paragraph>
      <Paragraph position="1"> b. Everyone who owns a Ford tunes the engine himself.</Paragraph>
      <Paragraph position="2"> Thus the range of antecedent-anaphor behavior that Partee calls attention to argues equally for an analogy between tense and pronouns as for an analgoy between tense and definite NPs.</Paragraph>
      <Paragraph position="3"> eAfter I say more about Me structure construction, I will be able to claim that tense can cause the listener to create a new position in e/s structure at which to attach the event or situation described in its associated clause. 7Clark &amp; Marshall \[2\] are among those who have described ~e necessary &amp;quot;common knowledge&amp;quot; that must be assumable by speaker and listener about the association for the spedfication to be successful. However, there are two more features of behavior to consider: On the one hand, as noted earlier, definite NPs have a capability that pronouns lack 8. That is, they can introduce a new entity into the discourse that is 'strongly' associated with the antecedent and is unique by virtue of that association, as in the b. examples above. Example 4 shows that tense has a similar ability. Thus, a stronger analogy can be drawn between tense and definite NPs.</Paragraph>
      <Paragraph position="4"> On the other hand, definite NPs have the capability to move the listener away from the current focus to a particular entity introduced earlier or a particular entity associated with it. This ability tense lacks. While tense can set up a new node in els structure that is strongly associated with its 'antecedent', it does not convey sufficient information to position that node precisely - for example, precisely relative to some other event or situation the listener has been told about. Thus its resemblance to definite NPs is only partial, although it is stronger-than its resemblance to pronouns. To locate a node precisely in e/s structure requires the full temporal correlate of a definite NP - that is, a temporal subordinate clause or a definite NP itself, as in Example 5.</Paragraph>
      <Paragraph position="5"> Example 5 The bus reached the Stadium, terminal for the suburban bus services. Here De Witt had to change to a streetcar.</Paragraph>
      <Paragraph position="6"> The wind had abated but the rain kept falling, almost vertically now. He was travelling to a two o'clock appointment at Amsterdam police headquarters in the center of town, and he was sure to be late.</Paragraph>
      <Paragraph position="7"> When De Witt got to the police president's office, he telephoned his house.</Paragraph>
      <Paragraph position="8"> \[adapted from Hans Koning, De Witt's War\] Notice that without the &amp;quot;when&amp;quot; clause, the simple past tense of &amp;quot;he telephoned his house&amp;quot; would be anaphorically interpreted with respect to the &amp;quot;reaching the Stadium&amp;quot; event, as happening sometime after that. A new node would be created in els structure ordered sometime after the &amp;quot;reaching the Stadium&amp;quot; event. On the other hand, with the &amp;quot;when&amp;quot; clause, that new node can be ordered more precisely after the &amp;quot;reaching the Stadium&amp;quot; event. By association with its &amp;quot;antecedent&amp;quot; (the &amp;quot;travelling to the appointment&amp;quot; event), it can be ordered after the achievement of that event.</Paragraph>
      <Paragraph position="9"> There is another advantage to be gained by pushing further the analogy between tense and definite NPs that relates to the problem tackled in \[6, 4, 12\] of how to reconcile the anaphoric nature of tense with the fact that the event or situation described in the next clause varies as to whether it is taken to be coincident with, during, before or after the event or situation described in the previous clause. This I will discuss in the next section, after introducing the notion of temporal focus.</Paragraph>
      <Paragraph position="10"> aexcept for &amp;quot;pronouns of laziness&amp;quot; which can evoke and specify new entities through the use of previous dascriptions</Paragraph>
    </Section>
  </Section>
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