17.5.4 Aspect

In the last section, we discussed ways to represent the time of an event with respect to the time of an utterance describing it. In this section, we address the notion of aspect, which concerns a cluster of related topics, including whether an event has ended or is ongoing, whether it is conceptualized as happening at a point in time or over some interval, and whether or not any particular state in the world comes about because of it. Based on these and related notions, event expressions have traditionally been divided into four general classes: statives, activities, accomplishments, and achievements. The following examples provide prototypical instances of each class.

Stative: I know my departure gate.

Activity: John is flying.

Accomplishment: Sally booked her flight.

Achievement: She found her gate.

Although the earliest versions of this classification were discussed by Aristotle, the one presented here is due to Vendler (1967). In the following discussion, we'll present a brief characterization of each of the four classes, along with some diagnostic techniques suggested in Dowty (1979) for identifying examples of each kind.

Stative expressions represent the notion of an event participant having a particular property, or being in a state, at a given point in time. As such, they can be

thought of as capturing an aspect of a world at a single point in time. Consider the following ATIS examples.

(17.45) I like Flight 840 arriving at 10:06.

(17.46) I need the cheapest fare.

(17.47) I have a round trip ticket for $662.

(17.48) I want to go first class.

In examples like these, the event participant denoted by the subject can be seen as experiencing something at a specific point in time. Whether or not the experience was in the same state earlier, or will be in the future is left unspecified.

There are a number of diagnostic tests for identifying statives. As an example, stative verbs are distinctly odd when used in the progressive form.

(17.49) *I am needing the cheapest fare on this day.

(17.50) *I am wanting to go first class.

We should note that in these and subsequent examples, we are using an $ {}^{*} $ to indicate a broadened notion of ill-formedness that may include both semantic and syntactic factors.

Statives are also odd when used as imperatives.

(17.51) *Need the cheapest fare!

Finally, statives are not easily modified by adverbs like deliberately and carefully.

(17.52) *I deliberately like Flight 840 arriving at 10:06.

(17.53) *I carefully like Flight 840 arriving at 10:06.

Activity expressions describe events undertaken by a participant that have no particular end point. Unlike statives, activities are seen as occurring over some span of time, and are therefore not associated with single points in time. Consider the following examples:

(17.54) She drove a Mazda.

(17.55) I live in Brooklyn.

These examples both specify that the subject is engaged in, or has engaged in, the activity specified by the verb for some period of time.

Unlike statives, activity expressions are fine in both the progressive and imperative forms.

(17.56) She is living in Brooklyn.

(17.57) Drive a Mazda!

However, like statives, activity expressions are odd when temporally modified with temporal expressions using in.

(17.58) *I live in Brooklyn in a month.

(17.59) *She drove a Mazda in an hour.

They can, however, successfully be used with for temporal adverbials, as in the following examples:

(17.60) I live in Brooklyn for a month.

(17.61) She drove a Mazda for an hour.

ACCOMPLISHMENT EXPRESSIONS Unlike activities, accomplishment expressions describe events that have a natural end point and result in a particular state. Consider the following examples:

(17.62) He booked me a reservation.

(17.63) United flew me to New York.

these examples, there is an event that is seen as occurring over some period of the that ends when the intended state is accomplished.

A number of diagnostics can be used to distinguish accomplishment events from activities. Consider the following examples, which make use of the word stop as a test.

(17.64) I stopped living in Brooklyn.

(17.65) She stopped booking my flight.

In the first example, which is an activity, one can safely conclude that the statement I lived in Brooklyn even though this activity came to an end. However, from the second example, one can not conclude the statement She booked her flight, since the activity was stopped before the intended state was accomplished. Therefore, although stopping an activity entails that the activity took place, stopping an accomplishment event indicates that the event did not succeed.

Activities and accomplishments can also be distinguished by how they can be modified by various temporal adverbials. Consider the following examples:

(17.66) *I lived in Brooklyn in a year.

(17.67) She booked a flight in a minute.

In general, accomplishments can be modified by in temporal expressions, while simple activities can not.

ACHIEVEMENT EXPRESSIONS

The final aspectual class, achievement expressions, are similar to accomplishments in that they result in a state. Consider the following examples:

(17.68) She found her gate.

(17.69) I reached New York.

Unlike accomplishments, achievement events are thought of as happening in an instant, and are not equated with any particular activity leading up to the state. To

be more specific, the events in these examples may have been preceded by extended searching or traveling events, but the events corresponding directly to found and reach are conceived of as points not intervals.

The point-like nature of these events has implications for how they can be temporally modified. In particular, consider the following examples:

(17.70) I lived in New York for a year.

(17.71) *I reached New York for a few minutes.

Unlike activity and accomplishment expressions, achievements can not be modified by for adverbials.

Achievements can also be distinguished from accomplishments by employing the word stop, as we did earlier. Consider the following examples:

(17.72) I stopped booking my flight.

(17.73) $ * $I stopped reaching New York.

As we saw earlier, using stop with an accomplishment expression results in a failure to reach the intended state. Note, however, that the resulting expression is perfectly well-formed. On the other hand, using stop with an achievement example is unacceptable.

We should note that since both accomplishments and achievements are events that result in a state, they are sometimes characterized as sub-types of a single aspectual class. Members of this combined class are known as telic eventualities.

Before moving on, we should make two points about this classification scheme. The first point is that event expressions can easily be shifted from one class to another. Consider the following examples:

(17.74) I flew.

(17.75) I flew to New York.

The first example is a simple activity; it has no natural end point and can not be temporally modified by in temporal expressions. On the other hand, the second example is clearly an accomplishment event since it has an end point, results in a particular state, and can be temporally modified in all the ways that accomplishments can. Clearly the classification of an event is not solely governed by the verb, but by the semantics of the entire expression in context.

The second point is that while classifications such as this one are often useful, they do not explain why it is that events expressed in natural languages fall into these particular classes. We will revisit this issue in Ch. 19 where we will sketch a representational approach due to Dowty (1979) that accounts for these classes.