Characterizing Indirect Speech Acts 1 
Gretchen P. Brown 
Computer Corporation of America 
575 Technology Square 
Cambridge, Massachusetts 02139 
This paper presents the core of a descriptive theory of indirect speech acts, i.e. 
utterances in which one speech act form is used to realize another, different, speech act. 
The proposed characterization of indirect speech acts is based on principles of goal 
formation, viewed in the context of a general structural model of action. The model of 
action is used to develop rules that characterize a large number of indirect speech act 
forms. Computational implications of the theory are discussed. 
1. Introduction 
In recent years, a considerable amount of attention 
has been devoted to the topic of indirect speech acts, 
i.e. utterances in which one speech act form is used to 
realize another, different, speech act. A simple exam- 
ple of an indirect speech act is the question form 1.1 
uttered with the intent to convey a request to close the 
door. 
1.1 Can you close the door? 
Despite the volume of work that has been done on 
indirect speech acts, fundamental questions remain 
unanswered. We still lack a complete answer to even 
the basic question of what forms can realize a given 
speech act. Two properties of the problem have made 
the search for a complete theory of indirect forms 
particularly difficult: 
1..Sheer numbers: There are a considerable 
number of different speech acts, and many 
have a wide selection of possible indirect re- 
alizations. A theory must be quite general to 
take these into account. 
2. Variety: Indirect speech act forms range from 
highly conventionalized to apparently free 
forms. It appears that no single, simple set 
of generalizations can adequately capture the 
complexity of indirect speech acts. 
1 The research for this paper was carried out while the author 
was on the staff of the Laboratory for Computer Science at the 
Massachusetts Institute of Technology. The research was supported 
by the Advanced Research Projects Agency of the Department of 
Defense and was monitored by the Office of Naval Research under 
Contract Number N00014-75-C-0661. 
It is the claim of this paper that previous inv~estigations 
of indirect speech acts (abbreviated ISAs 2) have been 
hampered by inadequate semantic theories. This study 
takes as primary the central tenet of speech act theory 
that language is action (Austin \[2\]) and brings to bear 
some of the perspectives on the representation of ac- 
tions developed in the course of Artificial Intelligence 
research. Accordingly, principles of goal formation 
are discussed in the context of a general structural 
model of action. The model of action is used to devel- 
op rules that characterize a large number of indirect 
speech act forms. 
The focus of this investigation is on the develop- 
ment of a descriptive theory of ISAs. Accounting for 
the diversity of ISAs is an important goal, but I see 
the formulation of a solid and complete descriptive 
theory as a necessary prerequisite to an explanatory 
theory. This is not to say that explanation can be 
totally decoupled from description, and, in fact, the 
use of the general model of actions to derive ISA 
forms has significant explanatory potential. To fully 
account for differences in ISA forms, however, we 
must have a good characterization of what these dif- 
ferences are. 
While the claims that will be made in this paper 
stop at a (partial) descriptive theory of ISAs, the un- 
derlying motivations do not. Computational consider- 
ations have played a significant role in the develop- 
ment of the ISA categorization. The work presented 
here grew out of the implementation effort reported in 
2 It is helpful to pronounce ISA as initials to avoid confusion 
with IS-A, the name used commonly in the Artificial Intelligence 
literature for a hierarchical semantic relationship. 
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150 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characterizing Indirect Speech Acts 
\[3\]. The actual behavior of the system was limited 
(internal manipulations for a twenty turn sample dia- 
logue), but the process model implemented was rela- 
tively sophisticated. A further expanded and refined 
version of this model is presented in \[4\]. 
In viewing the characterization of ISAs as a compu- 
tational problem, the central premise has been that the 
phenomenon of ISAs is too complex to admit to a 
single uniform computational treatment. The two 
stumbling blocks to a descriptive theory -- the number 
and variety of ISA forms -- are doubly troubling when 
the theory is to have a computational application. 
Some means must be found to divide the class of ISAs 
into subclasses which have their own specialized repre- 
sentations and processing strategies. The development 
of the descriptive theory of ISAs presented has been 
affected in various ways, subtle and not so subtle, by 
this computational hypothesis. The proper level of 
representation of ISA rules has been of primary con- 
cern, as has the identification of classes of ISAs ac- 
cording to the complexity of their derivations. 
Section 2 introduces some of the issues that have 
been raised about ISAs and Section 3 lays the ground- 
work for the approach taken here. Section 4 then 
presents a set of general rules that handle a large num- 
ber of ISA forms. The rules in that section are pro- 
posed as the core of a descriptive theory of ISAs. Is- 
sues surrounding the application of the rules are ad- 
dressed in Section 5. Finally, Section 6 discusses some 
of the implications of the theory, with comparison to 
recent computational work. 
2. Previous Approaches 
Two approaches to the characterization of indirect 
speech acts have been particularly influential for both 
computational and traditional linguists: the views pro- 
posed by Gordon and Lakoff and by Searle. Since the 
rules presented in this paper combine properties of 
each approach, we start with a brief description of 
each. 
We consider first the approach taken by Gordon 
and Lakoff \[12\]. Concentrating primarily on request, 
Gordon and Lakoff propose a set of what they call 
sincerity conditions and then give a single powerful 
rule to account for the different ways that a request 
can be framed. They say that to make a sincere 
request a speaker must, first, want the action done, 
second, believe that the hearer can do the action, 
third, believe that the hearer wants to do the action, 
and, fourth, believe that the hearer would not do the 
action unless asked to. The first of these sincerity 
conditions is called speaker-based and the remaining 
three are called hearer-based. The rule given is: 
One can convey a request by 
(a) asserting a speaker-based sincerity condition or 
(b) questioning a hearer-based sincerity condition. 
This formulation is attractive because it is so elegant 
and simple, but it is also, as the authors are the first to 
observe, only a preliminary answer. The conditions 
associated with request are incomplete, since they lack 
any mention of obligation relationships; these are dis- 
cussed below in Section 3.3. More problematic is the 
lack of detailed guidelines for extending the theory 
beyond requests. 
A second major approach to ISA regularities is that 
of Searle. Searle presents a more complete account of 
ISAs, proposing generalizations associated with the 
five major classes of speech act defined in \[26\]. In 
\[25\] he lists four generalizations for directives and five 
others for commissives. The generalizations are differ- 
entiated according to the parts of the speech act iden- 
tified in \[24\], i.e. propositional content conditions, 
sincerity conditions, and preparatory conditions. 
(Gordon and Lakoff's sincerity conditions, in contrast, 
seem to be an amalgam of Searle's sincerity and pre- 
paratory conditions.) 
Searle's contribution is a valuable one, in that he 
has succeeded in accounting for a broad range of 
speech acts. At the same time, Searle's generalizations 
can be questioned on the count that they are too spe- 
cific. Generalizations are stated in terms of types of 
preparatory conditions, rather than in terms of prepar- 
atory conditions as a whole. A more serious problem 
is the relegation of the notion of speaker- and hearer- 
based conditions to an informal role, as opposed to 
giving it an explicit place in the theory. 
The theory proposed in this paper is both a synthe- 
sis and a generalization of the two approaches. Rather 
than derive ISA forms from a single set of conditions 
associated with the speech act, as do Gordon aild La- 
koff, I follow Searle in looking for important classes of 
ISA forms based on different parts of the speech act. 
The theory presented goes a step further, however, 
looking beyond the structure of individual speech acts 
to derive ISA forms from very general principles of 
goal formation. 
3. Preliminaries 
We first introduce the model of actions on which 
the ISA rules will be based, and Section 3.2 looks at 
speech acts from the perspective of this model. Sec- 
tion 3.3 then discusses the request speech act as a basis 
for examples used throughout the paper. 
3.1. An Outline of the Structure of Actions 
If we are to follow Austin and Searle in the belief 
that language is, fundamentally, action, then linguistic 
models must include a model of the structure of ac- 
tions. Such a model of actions can be a unifying force 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 151 
Gretchen P. Brown Characterizing Indirect Speech Acts 
within the larger model, since structural information 
can be used in a number of different ways. This sub- 
section gives a very general treatment of actions, just 
enough to support the ISA rules proposed. The ac- 
count of actions is taken from the OWL-I representa- 
tion scheme (Szolovits et al. \[27\] and Brown \[3,6\]), 3 
and it has counterparts in work by Bruce \[7\], Schank 
and Abelson \[23\], Grosz \[14\], and Moore, Levin, and 
Mann \[18,19\]. Some of these approaches differ in the 
type of action modelled, and all of them differ in the 
details, but each of the approaches is open to the 
treatment of action representations as general knowl- 
edge. Thus, action representations are not merely 
programs for doing something, they are also knowledge 
structures that may be used by other processes. 
We start with the notion of a method, a representa- 
tion of an action. Methods have three main parts: a 
header, argument specifications, and a procedural 
body. The header is the method's unique name. Argu- 
ment specifications, organized by semantic cases, are 
used for type checking of inputs to the method (input 
cases) or to specify the form of results (output cases). 
The procedural body is divided into two parts: 
(optional) prerequisites and procedure steps. 
Note that input cases are associated with methods, 
not surface English verbs. Input case specifications 
give constraints on the participants in the method, the 
materials used, objects manipulated, etc. (A suggested 
set of semantic input cases derived by William A. Mar- 
tin can be found in \[4\].) An important type of input 
case constraint, the precondition, is discussed in the 
next subsection. 
Besides input case specifications, we said that me- 
thods may have associated output case specifications, 
i.e. specifications of results. One important notion 
here is that of principal result, which is the main result 
of the method and, typically, the reason that the me- 
thod is undertaken. For example, the action conveyed 
in "Paint the block red" has as principal result that the 
block is red. The paint brush may also end up red, 
but this is not the principal result. 
Turning to the method's procedural body, we need 
to know that procedure steps may correspond to sub- 
actions, i.e. they may be used as calls to other me- 
thods. Beyond this, procedure steps have a good deal 
of interesting structure, discussion of which is not 
necessary for the purposes of this paper. 
As for prerequisites, the ones that are of interest 
here are states. A stative prerequisite of an action is a 
condition that must obtain before that action is carried 
out. If the condition does not hold, then one must 
30WL-I was developed by William A. Martin, Lowell Haw- 
kinson, William Long, Alexander Sunguroff, William Swartout, 
Peter Szolovits, and the author. OWL has continued to develop 
since that time. 
bring it about before carrying out the action. An ex- 
ample of a prerequisite is the requirement that an ele- 
mentary course of study be completed before a more 
advanced one is undertaken. 
3.2. The Model of Actions Applied to Speech Acts 
Speech acts, because they are actions, can be repre- 
sented by methods. Speech act representations there- 
fore have semantic input cases, which typically include 
cases for the participants in the conversation and a 
case for what Searle calls the propositional content 
condition of the speech act (very roughly, what the 
speech act is "about") \[24\]. Among the constraints 
on these input cases are preconditions. Preconditions 
are constraints on the beliefs, desires, or other inten- 
tions of the agent of the method (the participant re- 
sponsible for the action) that should be satisfied be- 
fore the speech act gets underway. Preconditions 
differ from prerequisites in that a failure to satisfy 
preconditions typically means that a method is elimi- 
nated from consideration as a possible plan; a prere- 
quisite that is not satisfied merely adds extra steps to 
be performed. Preconditions will play an important 
role in the framing of ISAs; a sample set is given in 
the next subsection. 
A concept that will be useful in talking about ISAs 
is the intended effect. The intended effects of speech 
acts are those effects that P1 (the agent of the speech 
act) intends to have on P2. The most important of 
these effects will be called the principal intended effect. 
For request, the principal intended effect is that P2 
take responsibility for carrying out some action. For 
offer, it is that P2 accept the offer. "Accept" here 
includes not only a verbal acceptance, but also that P2 
perform some action that complements Pl's offer, e.g., 
P2 takes food that is offered. The notion of intended 
effect comes from Verschueren \[28\], but it has been 
adapted somewhat. In particular, for uniformity, in- 
tended effects will be restricted to be actions only, not 
states. For example, the principal intended effect for 
state is that P2 come to know (as opposed to just know) 
that P1 believes something to be a fact. 
Intended effects and principal intended effects can 
be related in a straightforward way to methods. In- 
tended effects are actions precipitating certain method 
results (i.e. intended effects are the direct causes); 
principal intended effects are actions precipitating 
certain principal results. The results and principal 
results are not necessarily associated with the speech 
act method but are instead associated with higher level 
methods that include both the speech act and its pro- 
totypical linguistic and nonlinguistic responses. 
Once speech acts have been set within the action 
representation, we can define ISAs more closely to 
delimit the phenomena of interest. Speech acts con- 
veyed by ISA forms are derivable from parts of, or 
152 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characl:erizing Indirect Speech Acts 
conditions associated with, the conveyed speech act(s). 
Other implications of an utterance may arise from a 
particular co-occurrence of steps within larger patterns 
of dialogue, but these implications will not be consid- 
ered to be conveyed speech acts. A very simple exam- 
ple of such an implication comes from a computer 
console session environment, where some users type 
"Thank you" in a place where others type "Thank 
you" followed by "Good-bye". When "Thank you" 
occurs alone in such a situation, it will not be consid- 
ered to be an indirect closing. Instead, the closing is 
seen as an optional step, which may be omitted in the 
presence of utterances that uniquely identify the place 
in the dialogue. Utterances that imply omitted steps 
do so based on relationships at a higher level of dia- 
logue structure than individual speech acts. 
3.3. Preconditions for Requests 
Although the rules presented in the next section are 
intended to apply to speech acts in general, examples 
will be drawn primarily from request forms. Since the 
ISA rules depend in part on the preconditions of a 
speech act, the preconditions of the speech act request 
are discussed here; preconditions for ask, state, offer, 
and suggest appear in the Appendix. 4 In these precon- 
ditions and throughout the paper, P1 is the originator 
of the utterance (or written message) and P2 is the 
receiver. If subsequent related utterances are dis- 
cussed, then P1 and P2 continue to refer to the same 
participants. Consider, then, the following precondi- 
tions for request: 
I. P1 wants P2 to take responsibility for car- 
rying out the action. 
II. P1 believes that P2 can take responsibility 
for carrying out the action. 
III. P1 believes that P2 is willing to take respon- 
sibility for carrying out the action. 
IV. P1 believes that P2 is obligated to P1 (and 
possibly to others) to take responsibility for 
carrying out the action. 
To clarify the terms used in the preconditions, I 
will outline some of the relationships that should be 
captured in a semantic network representation of 
them. 
The internal semantic node believe has a superclass 
relationship to semantic nodes for idea-holding con- 
cepts, e.g., thinking, knowing, assuming, and hypothes- 
izing. The different specializations (i.e. subclasses) of 
believe differ according to the strength of commitment 
to the belief. In addition, they differ according to 
4 In the interests of readability, preconditions and ISA rules 
are presented in this paper informally. The model of actions and 
rules have been represented in OWL-I, which implies a number of 
commitments, many shared by other representation schemes of the 
late seventies. These commitments are discussed further in Sect. 5. 
whether the belief is open to confirmation against 
some external reality (i.e., facts), will eventually be 
open to confirmation (i.e., guesses and predictions), or 
is generally considered to be a matter of taste (i.e., 
opinions). The link between the various specializa- 
tions of believe is the fact that beliefs can be partially 
supported by evidence, whether or not complete con- 
firmation of the beliefs is ultimately possible. This 
excludes idea-holding actions such as dreaming. 
In precondition I, the internal node want has a su- 
perclass relationship to semantic nodes for all goal- 
holding concepts, e.g., desiring and hoping. "Take 
responsibility" is used in the preconditions to permit 
subcontracting. Whether P2 does all the action steps 
or not, P2 still remains responsible to P1 for the re- 
suits. 
In precondition II, "can" is meant to convey the 
general notion of enablement for actions. One spe- 
cialization of the semantic node can is may, enable- 
ment through permission. The internal representation 
for "can" is discussed further in Section 5. 
In the third precondition, the internal node for "be 
willing" has a superclass in common with want 
(perhaps called "be inclined") but it differs in that if 
P2 is willing to do action A1, he or she is not disin- 
clined to do it. That is to say, P2 does not necessarily 
have A1 as a goal, but P2 has no conflicting goals 
which, when weighed against A1, result in a decision 
against adopting A1 as a goal. Precondition III is 
worded "P2 is willing to" rather than "P2 wants to," 
because P2 will not necessarily already have the action 
requested as a goal at the time that P1 makes the 
request. 
Finally, we come to the notion of obligation in 
precondition IV. The concept of obligation assumed is 
a more specific version of the generalized obligation 
that Labov and Fanshel use for requests in \[16\]. Obli- 
gation to other people is seen here as coming in three 
types: role obligation, authority obligation, and the 
general obligation to be cooperative. Role obligations 
are associated with roles, which can be seen as pat- 
terns of behavior that can be assumed by individuals 
for varying periods of time. An example of a role 
obligation would be the requirement that a bank teller 
fulfill a request to make change. Authority obligations 
are slightly more difficult to identify, since, especially 
in contemporary American society, most authority 
arises from roles. Authority obligations based on age 
differences are probably the most prevalent examples. 
The third type of obligation, the general obligation to 
be cooperative, seems to arise simply from a need, 
often in the form of a temporary inequality between 
individuals. The obligation applies in a range of situa- 
tions. A typically mundane version of the obligation is 
that questions should be answered, i.e. that inequali- 
ties of knowledge should be corrected. A more serious 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 153 
Gretchen P. Brown Characterizing Indirect Speech Acts 
version is the injunction to help someone in an emer- 
gency. Note that this obligation is not absolute (nor 
are role or authority obligations), and it may be over- 
ridden by other obligations. A point worth mentioning 
is that my notion of obligation includes the notion of 
Pl's right to invoke the obligation. (See \[16\], p. 78.) 
An obligation is seen as a three-place relationship 
between P1, P2, and the thing that P2 is obliged to do. 
Note that the specific persons P1 and P2 need not be 
named explicitly in the obligation. For example, the 
obligation to drive carefully may be an obligation to 
society in general, and hence to any individual P1 by 
inclusion in the larger set. Given this formulation, P1 
has the right to invoke the obligation to drive carefully 
because P1 is one of the parties to the obligation, even 
if P1 is not named explicitly.5 
Philosophical controversy surrounds several of 
these terms, and a complete and detailed definition for 
any of them is a research project in itself. The com- 
ments on the terms used in the preconditions are 
sketchy, but the intent of the comments is to give the 
reader enough information to evaluate the approach to 
ISA characterization proposed in this paper. 
4. A Set of General Rules for Indirect Speech Acts 
If one looks carefully at a varied group of indirect 
speech acts, an outline of a common sense view of 
rational behavior begins to emerge. This common 
sense view can be used as a conceptual organization of 
ISA forms, an approach taken here in the presentation 
of a set of general rules for ISAs. 
4.1. Some Basic Observations 
We start with some very basic observations, none 
of which should seem particularly remarkable since the 
phenomena involved lie just below the surface, and 
sometimes right at the surface, of English (and other 
languages as well). 
Strategy 1. If you believe that a proposition 
holds, you can tell someone. 
Strategy 2. If you want to know whether a 
proposition holds, you can ask someone if it 
holds. 
Strategy 3. If you want to know whether a 
proposition holds, you can ask someone if it 
does not hold. 
These three communication strategies are extensions 
of the observations made by Searle and built into Gor- 
don and Lakoff's rule for requests. "Can" is used 
above to indicate that other options do, of course, 
exist; these are merely the options of interest for ISAs. 
5 Reminders are one class of utterance in which P1 does have 
the right to invoke an obligation without being a party to it. This is 
not necessarily a problem for requests, however, because reminders 
can be treated as separate speech acts. 
The three strategies can be augmented by what will be 
called here the better-knowledge principle: if both you 
and a conversational partner have a degree of knowl- 
edge about a proposition, the decision whether to tell 
what you know (or think) or ask what the other per- 
son knows (or thinks) can be made based on which 
participant has the better knowledge of the proposi- 
tion. 
Moving from information exchanges to actions in 
general, we can identify some basic factors in the 
process of undertaking an action (i.e. adopting the 
action as a goal, not necessarily with the intent of 
being the agent yourself). 
1. One should only undertake actions that are 
necessary. 
2. One should only undertake actions for which 
some desirable result or results can be ex- 
pected. 
3. One should only undertake actions that one 
expects to be possible. 
These three maxims, which will be referred to as the 
maxims of Necessity, Desirability, and Possibility, 
summarize factors that should be weighed in goal for- 
mation, the process of deciding to adopt some action 
as a goal. Necessity, desirability, and possibility of 
actions are not necessarily, of course, evaluated inde- 
pendently, but the maxims abstract away from the 
actual weighing procedure. Interpretation of these 
maxims is intended to be quite broad. "Necessity" is 
assumed here to include obligations, and "possibility" 
is assumed to include having permission. 
Readers familiar with the classic work of Grice on 
conversational implicature \[13\] will recognize the ap- 
proach that is being taken. Grice suggests four cate- 
gories of maxims that are applicable to linguistic ac- 
tions but which have analogues in other types of ac- 
tions. The maxims given here are applicable to actions 
in general but apply to speech acts as a special case. 
The Maxim of Necessity above has a partial counter- 
part in Grice's category of Quantity. The other two 
maxims have no direct counterparts, and they suggest 
extensions to Grice's framework. 
Given these basic observations about communica- 
tion and action in general, the question is how they 
should be incorporated into a theory. One possible 
approach is to represent the observations at essentially 
the level of generality given, then derive ISA forms by 
a uniform inference process. Here, in contrast, the 
observations will be used as a conceptual organization 
and as a guide to rule specification. The resulting 
rules will be more specialized, but they will be at a 
level closer to the ISA forms that they describe. 
The motivation for the choice of this approach can 
better be described after the rules have been present- 
ed. Accordingly, the rest of this section discusses 
154 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characterizing Indirect Speech Acts 
rules associated with the maxims of Necessity, Desira- 
bility, and Possibility. 
4.2. Rules Related to the Maxim of Necessity 
The Maxim of Necessity says that one should act 
only when necessary, avoiding extraneous actions. 
The following rules account for speech act forms relat- 
ed to this maxim: 
P1 can convey a speech act indirectly by -- 
Rule NECESSARY-ASSERT 
-- asserting that the intended speech act is neces- 
sary 
e.g., the request "I have to ask you to shut the 
door." 
Rule NECESSARY-ASK 
-- asking whether the intended speech act is neces- 
sary 
e.g., the request "Do I need to ask you to shut 
the door?" 
Rule EQUI-ASK 
-- asking whether an equivalent speech act (i.e., 
one with the same principal intended effect) has 
already been performed 
e.g., the request "Did anyone ask you to take 
out the garbage?" 
Rule FUTURE-EFFECT-ASK 
-- asking whether the principal intended effect can 
be expected to occur without the speech act 
e.g., the requests: 
"Are you planning to take out the garbage?" 
"Are you going to take out the garbage?" 
Rule PAST-EFFECT-ASK 
-- asking whether the principal intended effect of 
the speech act has already occurred 
e.g., the requests: 
"Did you take out the garbage?" 
"Have you taken out the garbage?" 
and, using additional rules (see Section 5), 
"Is the garbage out?" 
"Assert" is used in these and subsequent rules to in- 
elude the speech acts of stating a fact and giving an 
opinion, i.e., those speech acts that Searle calls repre- 
sentatives \[26\]. 
The "necessity" rules exemplify the three commu- 
nication strategies listed at the beginning of this sec- 
tion. NECESSARY-ASSERT exemplifies the first 
strategy, in which P1 tells what he or she knows about 
the necessity of the speech act. In NECESSARY- 
ASK, P1 asks whether the speech act is necessary 
(strategy 2), and in the last three rules, P1 asks 
whether the speech act is unnecessary (strategy 3). 
Note that there is no rule for the explicit version of 
the third strategy, e.g. for the form "Is it unnecessary 
for me to <speech act>?" This form is practically 
incomprehensible as a way to carry out the speech act, 
even though the reasoning involved is comparable to 
that for the EQUI-ASK form. Perhaps this gap re- 
fleets a preference for more specialized forms. The 
three strategy-3 rules for necessity, which are more 
specific, supersede the explicit "Is it unnecessary..." 
form. 
Gordon and Lakoff use a condition analogous to 
the FUTURE-EFFECT-ASK rule to account for the 
"Will you <action>?" request form. In this interpre- 
tation, the form asks if the request is unnecessary be- 
cause P2 was going to perform the desired action any- 
way. While this approach is plausible on the face of 
it, some uses of the "will" form are not motivated by 
questions of the necessity of the action. Consider, for 
example, 4.1: 
4.1 Will you accept a ride to the airport? 
One can view example 4.1 as P1 asking P2 whether 
the outcome of an offer by P1 will be successful (i.e., 
acceptance). This example can therefore be accounted 
for by the Maxim of Possibility; "will" forms are dis- 
cussed further in Section 4.4. 
Finally, note that P1 is permitted to use an ISA 
only when P1 can reasonably expect P2 to decipher 
Pl's intent, i.e., to recognize the indirection. Neither 
the "necessity" rules nor any of the other rules to be 
presented here, however, include this information. It 
appears that this constraint is part of a more general 
constraint that P1 avoid ambiguity. That is, P1 is 
obligated -- to the best of his or her ability -- to frame 
any utterance (ISA or not) in such a way that P2 can 
understand the message that P1 intended to convey. 
See Grice \[13\] for discussion of an "avoid ambiguity" 
maxim. 
4.3. Rules Related to the Maxim of Desirability 
Next we come to the Maxim of Desirability, which 
says that one should initiate actions for which some 
desirable result or results can be expected and avoid 
actions for which an undesirable result or results can 
be expected. Related to this maxim, we have the fol- 
lowing ISA rules: 
P1 can convey a speech act indirectly by -- 
Rule DESIRABLE-ASSERT 
-- asserting that some desirable result or results can 
be expected or some undesirable result or results 
can be avoided for some intended effect of the 
speech act. 
e.g., the request "I'11 be happier when you sub- 
stantiate those figures." 
Here, the desirable result is the happiness of P1, 
and the intended effect of the request is that P2 
substantiate the figures. 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 155 
Gretchen P. Brown Characterizing Indirect Speech Acts 
Rule DESIRABLE-ASK 
-- asking whether some desirable result or results 
can be expected or whether some undesirable result 
or results can be avoided for some intended effect 
of the speech act. 
e.g., the request "Will more light come in if you 
move it a little to the right?" 
Rule UNDESIRABLE-ASK 
-- asking whether some undesirable result or results 
can be expected from the intended speech act. 
e.g., the request "Will you be offended if I ask 
you to loan me some money?" 
For the first two rules, note that the intended ef- 
fect need not be an immediate result of the speech act; 
it may be several times removed in the causal chain. 
Similarly, the desirable result need not be an immedi- 
ate result of the intended effect. 
The "desirability" rules exemplify the three linguis- 
tic strategies listed at the beginning of this section. 
Again, as for the strategy-3 "necessity" rules, 
DESIRABLE-ASSERT and DESIRABLE-ASK do not 
include the most general possible forms. For example, 
no rule has been given to permit example 4.2 to be 
interpreted as an indirect request that P2 be quiet. 
4.2 I will be happier if I ask you to be quiet. 
Whereas DESIRABLE-ASSERT is framed in terms of 
an intended effect of the speech act, example 4.2 ref- 
ers to the speech act explicitly. The same hypothesis 
applies for this gap: the more specialized 
DESIRABLE-ASSERT has displaced the explicit, and 
more general, form exemplified by 4.2. 
4.4. Rules Related to the Maxim of Possibility 
The third maxim proposed was the Maxim of Possi- 
bility: one should only initiate actions that one expects 
to be possible. This means that a speech act should 
only be initiated when: 
1. P1 has the appropriate authority or permis- 
sion for the speech act; and 
2. it appears likely that the specific precondi- 
tions associated with the action's method 
can be satisfied. 
Only the second case, preconditions, will be consid- 
ered here. The ISA forms derived from the first case 
all seem to belong to a class that Fraser has called 
hedged performatives, and which are well accounted for 
in \[11\]. 
The approach taken for ISAs based on precondi- 
tions will be to distinguish three classes of precondi- 
tion and formulate six rules using the classes distin- 
guished. The classes will be based on the better- 
knowledge principle from the beginning of this section, 
specialized in terms of preconditions. The classes of 
precondition are as follows: 
1. Pl-based preconditions 
Here P1 has inherently better knowledge of 
whether or not the topic of the precondition 
holds. The topic of preconditions that begin 
here with "P1 believes that P2" is considered to 
be the direct object of the initial "believe," i.e., 
the rest of the precondition. For other precon- 
ditions, the topic is the entire pattern. Precondi- 
tions that are Pl-based represent intentional 
states of P1, i.e., beliefs, intentions, wants, de- 
sires, and degrees of willingness. An example is 
request I, P1 wants P2 to take responsibility for 
carrying out the action. 
2. P2-based preconditions 
Here P2 has inherently better knowledge of 
whether or not the topic of the precondition 
holds. Preconditions that fit this category in- 
clude Pl's beliefs about P2's intentional states. 6 
An example of a P2-based precondition is 
request III, P1 believes that P2 is willing to take 
responsibility for carrying out the action. 
3. Unmarked preconditions 
For these preconditions, determination of which 
participant has better knowledge of the precon- 
dition depends on properties of the context or 
its particular speech act. Examples are request 
II and IV. 
Using these precondition types, we can construct 
the following six rules for ISA forms. 
P1 can convey a speech act indirectly by -- 
Rule P1-ASSERT: 
-- asserting a Pl-based precondition of the 
speech act; e.g., 
"I want you to water the plants." (request I) 
"I hope you will use common sense." 
(request I) 
Rule P2-ASK: 
-- an ask of the topic of a P2-based precondi- 
tion of the speech act. 
e.g., "Do you want to shut the door?" 
(request III) 
Rule UNMARKED-ASK: 
-- an ask of the topic of an unmarked precondi- 
tion of the speech act. 
This rule applies in a context where P1 believes 
P2 has better knowledge of the condition in the 
precondition topic. 
e.g., "Is it your turn to do the dishes?" 
(request IV) 
6 An exception is the degree of knowledge of facts, which will 
be classified as an Unmarked condition. There are cases in which 
P1 is assumed to have better knowledge about what P2 knows or 
does not know than P2. Such an assumption underlies the use of 
the form "You don't know <fact>" as a way to state the fact. 
156 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characterizing Indirect Speech Acts 
Rule UNMARKED-ASSERT: 
-- asserting the topic of an unmarked precondi- 
tion of the speech act. 
This rule applies in a context where P1 believes 
P1 has better knowledge of the condition in the 
precondition topic. 
e.g., "It's your turn to do the dishes." 
(request IV) 
Rule COMPOSITE-REQUEST: 
-- a request form of an action that is a goal of 
P1. 
This rule is applicable only when the speech act 
has preconditions that are exact matches or spe- 
cializations of the four preconditions of request. 
e.g., "Take a cookie." (offer IV-VII, in Ap- 
pendix) 
Rule COMPOSITE-ASK: 
-- an ask about whether P2 will take responsi- 
bility for carrying out an action that is a goal of 
P1. 
This rule is applicable only when the speech act 
has preconditions that are exact matches or spe- 
cializations of the four preconditions of request. 
e.g., "Will you accept a ride to the airport?" 
(offer IV-VII, in Appendix) 
The rules as written do not account for differences 
in tense and mood. That is, the UNMARKED-ASK 
rule accounts for example 4.3 but not 4.4 and 4.5. 
4.3 Are you able to drive Sarah to school? 
4.4 Will you be able to drive Sarah to school? 
4.5 Would you be able to drive Sarah to school? 
Examples 4.4 and 4.5 can be handled as legitimate 
requests if we extend the rules to account for a wider 
range of tense and mood behavior. See \[4\] for sugges- 
tions. 
The "possibility" rules given also do not derive 
"not" forms, i.e. strategy-3 rules related to whether an 
action is impossible. 
4.6 Shouldn't you shut the door? 
4.7 Can't you shut the door? 
Note, however, that the rules given can be used as 
patterns for producing rules that account for examples 
4.6 and 4.7. Any of the rules above that involve an 
ask have rule counterparts with not inserted after the 
ask. 7 
In terms of specific rules, UNMARKED-ASSERT 
may seem odd when applied to preconditions involving 
7 This is a change from \[4\], where the "not" forms were seen 
as realizations of a different speech act, with different precondi- 
tions. The "not" forms are now seen as requests with a particular 
set of connotations. The motive for the change is to make the 
"possibility" rules consistent with the rules for the maxims of Ne- 
cessity and Desirability by allowing the strategy of questioning 
whether a condition does not hold. 
capability, producing indirect requests such as example 
4.8. 
4.8 You can open the door. 
Such forms do occur, however, particularly in requests 
to children where there may be some question of the 
child's capability to perform the action requested. 
COMPOSITE-REQUEST and COMPOSITE-ASK 
differ most from rules in previous theories because 
they are based on groups of preconditions. The 
COMPOSITE-ASK rule is of special interest. In 
Searle's scheme, the very common "Will you 
<action>?" form is derived from the propositional 
content condition of directives (the class that includes 
request). This approach seems to produce the correct 
forms, but it is basically a structural account, without 
strong semantic motivation. Instead, the approach 
taken here is to appeal to the Maxim of Possibility. 
The appearance of the four request preconditions in a 
set of preconditions indicates an action that P1 wants 
done. We can think of a speech act with this precon- 
dition subset as an act with a component request. By 
using a "will" form to perform the speech act, e.g. the 
offer example 4.1, P1 is asking a question about how 
P2 will respond to the offer, i.e., whether the compo- 
nent request will have a satisfactory response. When 
the speech act is itself a request, then the question in 
the "will" form is whether the speech act as a whole 
will have a satisfactory response. 
The distinction between Pl-based, P2-based, and 
Unmarked preconditions is probably uncontroversial; 
the question is whether the categories should be given 
a primary place in the theory. The reason that the 
better-knowledge split has been given a central place 
is that there is then a distinction between knowledge 
about a precondition that is independent of context 
(P1- and P2-based) and that which is not (Unmarked). 
Instead of deriving the invariant knowledge from first 
principles each time, it is "precompiled" into the rules. 
This choice reflects an approach that will be discussed 
in Section 6. 
4.5. The Scope of the Rules 
Starting with a general evaluation of the scope of 
the rules, note that they do not account for such phe- 
nomena as sarcasm, jokes, or failure to make standard 
choices (e.g., P1 makes an utterance and has not de- 
cided whether it is a question or a request for a non- 
verbal action). Another phenomenon specific to 
speech acts that complicates theory building is what 
can be called force shift. This occurs when one speech 
act form is used to "masquerade" as another. For 
example, one may use a suggestion form such as "How 
about picking up the blocks now?" in an environment 
where authority and role relationships make it clear 
that the utterance is functioning as a command. In 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 157 
Gretchen P. Brown Characterizing Indirect Speech Acts 
general, force shift seems to be used to give P1 the 
appearance of greater benevolence or to save face for 
P2. 
What these phenomena have in common, I think, is 
their "second order" nature. All can be seen as pre- 
supposing a set of rules and then deviating from them. 
I expect these phenomena to be modelled by the 
mechanisms for rule application, not accounted for by 
individual rules alone. Since such mechanisms could 
be expected to build on, and interact with, the "first 
order" rule application mechanism, these phenomena 
have been considered beyond the scope of the current 
investigation. 
The rules in this section are proposed to hold for 
speech acts in general. ISAs are not grounded solely 
in individual speech acts, as for Gordon and Lakoff, or 
even in types of speech acts as for Searle. Instead, 
they are related to a broader view of rational action 
analogous to that expounded by Grice. Speech acts, 
because they are actions, do have structural compo- 
nents that play an important part in the derivation of 
ISAs. The driving force behind ISAs, however, is the 
process of goal formation, i.e. the process of deciding 
whether to adopt a speech act as a goal. This process 
is reflected in the three maxims that were used as a 
conceptual organization for the presentation. This 
emphasis on the goal formation process is closely rela- 
ted to the work of Allen, Cohen, and Perrault 
\[1,8,21\]. The similarities and differences between the 
two approaches are discussed in Section 6. 
5. Relating Utterances to the General Rules 
The general ISA rules in the last section were illus- 
trated with English sentences, but nothing has as yet 
been said about the correspondence between particular 
utterances and rules. This section discusses in broad 
terms the nature of the correspondence, focusing on 
differences in complexity. Because the topic is diffi- 
cult to present in a neutral way, it will be approached 
from the point of view of language recognition, i.e., 
matching utterances against rules. Much of what is 
said, however, is relevant for generation as well. Note 
that discussion in this section is restricted to the issue 
of proposing correct matches; issues related to choos- 
ing between alternative interpretations of an utterance 
(i.e., alternative matches) are deliberately avoided. 
(See, however, \[4\]). 
5.1. Levels of Matching Complexity 
Any discussion of matching rests on a set of as- 
sumptions about the representations involved. We 
briefly outline some of the assumptions made here, 
starting with a distinction between two levels of repre- 
sentation: surface and internal. 
Each utterance is expected to have (at least) a 
surface representation and an internal representation. 
Internal representations are also used for action struc- 
tures, including preconditions, and for ISA rules and 
patterns. Internal representations are organized in a 
knowledge base according to a semantic network for- 
malism. Surface representations closely reflect the 
surface form of an utterance, and only those distinc- 
tions forced by the parsing process are made. Thus, 
noun group references not needed by the parser may 
remain unresolved (e.g., "I saw him"). Choices 
among systematically ambiguous relationships of con- 
stituents and choices among ambiguous word senses 
also need not be made unless they are forced. ISA 
forms are preserved; e.g., "Can you close the door?" 
would have a surface representation that records its 
interrogative nature and that contains a surface item 
corresponding to "can." 
An important implication of these attributes is that 
surface representation draws from a different vocabu- 
lary of semantic items than internal representation. 
For example, the surface item "believe" used in repre- 
senting "I believe you're fight" is related to, but is not 
the same as, the internal item "believe" that corre- 
sponds to the general idea-holding concept from Sec- 
tion 3.3. Surface items do, however, have associated 
internal level definitions which specify the ways that 
they can be translated into internal level representa- 
tions. These definitions include various potential 
translations; context is typically called on in each indi- 
vidual case to choose among alternatives and to speci- 
fy details. 
The problem for ISA matching, then, is to relate 
the definitions of items in the surface representation of 
an ISA to ISA patterns. The ISA patterns are pro- 
duced by applying the general rules from the last sec- 
tion to the method representations of particular speech 
acts. Matching will be discussed using as an example 
the pattern produced by applying rule UNMARKED- 
ASK to request precondition II: 
P1 asks whether P2 can take responsibility 
for carrying out action A. 
Consider, then, the following examples interpreted as 
indirect requests. 
5.1 Can you close the door? 
5.2 Are you able to close the door? 
5.3 Are you permitted to close the door? 
5.4 Can you please close the door? 
5.5 Will you be home in time to walk the dog? 
5.6 Have you got a hammer to put up that hook? 
5.7 Must you smoke? 
5.8 Can you reach the salt? 
5.9 It's cold in here. 
158 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characterizing Indirect Speech Acts 
Examples 5.1 to 5.3 can be handled by a set of 
general purpose matching rules that reflect hierarchical 
relationships in the knowledge base. The "can" in 
example 5.1 matches can in the above ISA pattern, 
since we can expect surface "can" to have internal can 
as a major part of its associated definition. (Other 
components in the definition might include the conno- 
tations of the lexical item.) Similarly, "are you able" 
in example 5.2 is an exact match, since we can also 
expect its associated definition to contain can as a 
component. In example 5.3, "permitted" has may as a 
component in its definition, and in the knowledge base 
may is a specialization (i.e., subclass) of can. 
The important point in these matches is that ele- 
ments of internal level definitions of surface items are 
related to elements of ISA patterns via the hierarchical 
relationships of the knowledge base, i.e., via prede- 
fined classification links. Thus, proposing the request 
interpretation for examples 5.1 to 5.3 involves rela- 
tively well understood knowledge base manipulations. 
Example 5.4 is a typical utterance that is not ac- 
counted for by the ISA patterns given. The problem is 
that example 5.4, a question according to its interroga- 
tive form, contains "please", a construct reserved for 
request and related speech acts. Utterances of this 
form have been much-discussed in the literature (e.g. 
Sadock \[22\], Searle \[25\], and Morgan \[20\]). The 
question is whether this form has evolved to the point 
that it is "really" a request only, no longer also a ques- 
tion. The interest is fueled by questions of the nature 
of meaning that are involved. Because I am interested 
in focusing on generalizations possible about ISAs, 
these issues will be omitted from discussion here. It is 
worth noting, however, that, whatever the ultimate 
theoretical disposition of these forms may be, they will 
probably have to be handled in a computational sys- 
tem by specialized patterns, to represent their unique 
properties. One such representation scheme, closely 
related to Morgan's notion of short-circuited 
entailment, is given in \[4\]. 
The rest of the examples above, 5.5 through 5.9, 
can be related to the "can" request pattern in a regular 
fashion, but they require a richer set of matching rela- 
tionships. Example 5.5 is typical of examples for 
which proposing a match may turn out to involve arbi- 
trarily complex inference. To begin to account for 
example 5.5, we can posit some link between can in 
the ISA pattern and a representation for being in the 
appropriate spatial proximity to do an action. This 
link may be hierarchical, or part of a definition related 
to the internal node can, or both. 
This treatment does not, however, fully solve the 
problem exemplified by example 5.5. There is still a 
good distance between the relationship of being at 
home with a dog and the idea of being in the fight 
range to perform the action of taking it for a walk. 
The level of detail in the utterance is so much more 
specific than the level of detail in the pattern that we 
cannot expect a match by merely traversing precom- 
puted links in a knowledge base. Another difference 
between 5.5 and the previous examples is that the 
knowledge needed to propose the match may go be- 
yond information conveyed by the utterance to infor- 
mation from the surrounding context. Either of these 
two factors has the potential to turn the process of 
proposing interpretations for utterances such as exam- 
ple 5.5 into a full-blown inference process, with all the 
attendant difficulties in controlling the inference. 
The rest of the examples can be expected to be 
more tractable, because we can take advantage of 
specialized links in the model of actions introduced in 
Section 3. Example 5.6 makes a "can you" request by 
asking whether P2 has an assignment (the hammer) 
for the instrument semantic case of the action (putting 
up a hook). Several different types of semantic cases 
can be queried in this way (see \[4\]); the structural 
model of actions supplies links between actions and 
their cases that can be traversed in this match. 
For examples 5.7 to 5.9, we can again exploit the 
model of actions to propose matches. The three ex- 
amples may have request interpretations where the 
actions intended are, respectively, that P2 stop smok- 
ing, pass the salt, and close the window. Note that 
none of the three examples describes these actions 
explicitly, and for that reason I have called utterances 
of this class implicit-action ISAs. These three exam- 
ples represent three classes of implicit-action ISAs, 
which differ in the complexity of the search needed to 
propose a match. For example 5.7 there is essentially 
no search; the implicit action is merely that P2 stop or 
avoid the action named. Example 5.8 names a prere- 
quisite of the implicit salt passing action. Recall from 
Section 3.1 that prerequisites are among the basic 
parts of methods. Other components of actions, in- 
cluding semantic input cases, steps, and principal re- 
suits, may also be used in implicit-action ISAs. All of 
these are related to the action by the explicit links of 
the method representation. Finally, example 5.9 al- 
ludes to the intended action by stating a basis for the 
action, i.e., a condition seen as sufficient to warrant 
the action. "Basis for action" can be related to the 
structural links of methods (see \[4\]), but the relation- 
ship between the condition named in the utterance and 
the implicit action is relatively complex. Implicit- 
action ISAs are discussed in more detail in \[5\]. 
We have, then, classes of utterances that obey rela- 
tively constrained matching relationships and classes 
that could involve an arbitrary inference process to 
propose interpretations. In between is a set of utter- 
ances for which proposal of interpretations can utilize 
structural links within action representations. Difficult 
problems of search and knowledge structuring remain 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 159 
Gretchen P. Brown Characterizing Indirect Speech Acts 
unsolved, but the links identified at least specify the 
types of paths that we can expect to see in matches of 
ISA patterns. 
5.2. Embedded ISAs 
In the discussion of matching, the initial assumption 
was that matching of surface representations occurred 
against patterns produced by single applications of 
rules to speech act methods. This assumption makes 
no provision for embedded forms. Some evidence 
does exist for this approach. For example, Sadock 
\[22\], in another context, observes that 5.10 is not a 
request for the hearer to move over, even though the 
similar form 5.11 is. 
5.10 Tell me if you can move over. 
5.11 Can you move over? 
In terms of the rules presented in Section 4, a request 
interpretation for 5.10 could only come from an em- 
bedded rule application: the UNMARKED-ASK rule 
applied to request II, resulting in ask, then the 
COMPOSITE-REQUEST rule applied to four of the 
preconditions of ask (see the Appendix). Forbidding 
such a double application effectively blocks a request 
interpretation, leaving only the information-seeking 
alternative. 
This straightforward solution, augmented by vari- 
ous classes of exceptions, was adopted in \[4\]. The 
embedded examples that have accumulated since, how- 
ever, are too numerous to be accounted for simply as 
exceptions. Consider the following indirect requests: 
5.12 I wonder if you can move over. 
5.13 I believe it's your turn to do the dishes. 
For 5.12, the internal level definition of wonder would 
include the following information: 
P1 wonder if <action or state> 
1. P1 wants to know if <action or state> 
2. P1 is speculating if <action or state> 
Example 5.12 is eharacterizable by applying rule P1- 
ASSERT to ask I (P1 wants to know the answer to the 
question) after applying rule UNMARKED-ASK to 
request II. Example 5.13 is eharacterizable by apply- 
ing rule P1-ASSERT to state I (P1 believes X is a 
fact) after applying rule UNMARKED-ASSERT to 
request IV. 
These examples, and others like them, seem to be 
best accounted for by politeness conditions. 8 In partic- 
ular, I suggest the following hypothesis: embedding of 
general ISA rules is permitted when it furthers the 
politeness intentions of P1, either to heighten polite- 
8 "Politeness" is used here quite broadly to include not only 
observation of the conventions of etiquette, but also the expression 
of respect for the other participant and the expression only of 
emotions harmonious with the social expectations associated with 
the conversational environment. 
ness or to lessen it. These processes are referred to 
here as mitigation and aggravation, respectively. (The 
terms are borrowed from Labov and Fanshel \[16\] but 
apply to a somewhat broader range of phenomena 
here.) Embeddings within rules that are unmarked for 
politeness are forbidden, as are embeddings where the 
rules involved have conflicting politeness markings. 
Evidence for this hypothesis is found in comparing 
example 5.12 to 5.14: 
5.14 I want to know if you can move over. 
Example 5.14 is derivable from the same set of rules 
as 5.12, but 5.12 conveys a request force while 5.14 
does not. The reason for this, I suggest, is that the 
UNMARKED-ASK rule is a mitigator: questions, in 
general, promote politeness by giving P2 an opportuni- 
ty to answer, allowing P2 to refuse to accept Pl's 
goals in uttering the speech act. "I wonder" is similar- 
ly undemanding: the emphasis is more on the specula- 
tion process P1 is involved in than the "wanting to 
know" aspect. In contrast, the "I want to know" in 
5.14 works in the direction of aggravation. A goal 
stated explicitly leaves P2 very little room to refuse P1 
without doing so explicitly. In narrowing P2's options, 
P1 has lowered the level of politeness. Example 5.12, 
then, with both rule applications working in the direc- 
tion of mitigation, is a permitted embedding. Example 
5.14, with one rule application producing mitigation 
and one aggravation, is blocked as an indirect request. 
This approach can also be used to explain the block 
on embedding in example 5.10. The COMPOSITE- 
REQUEST rule realized with an imperative is not a 
mitigator, while the UNMARKED-ASK rule realized 
with a question is. Thus, the indirect request interpre- 
tation is blocked. 
The examples presented make a case for the use of 
politeness conditions to govern ISA rule embedding, 
but it must be emphasized that more work is needed. 
Despite the work on politeness conditions, much of 
this area is not well understood. (For three different 
perspectives on the implications of ISA choices, see 
Lakoff \[17\], Davison \[9\], and Ervin-Tripp \[10\].) Con- 
elusive proof or disproof of the hypothesis awaits an 
analysis of the implications of ISA choices at a level of 
detail and completeness that is not yet available. 
6. Computational Implications 
This paper has characterized a significant number 
of ISA forms, with attention to representational issues. 
As noted in the introduction, these are the only claims 
made, although the ultimate motivation of the work 
was not only computational but was directed by a 
particular computational philosophy of language recog- 
nition. This philosophy will be described briefly here, 
with emphasis on the way that the theory presented 
fits into it. Due to the number of issues involved, I 
160 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characterizing Indirect Speech Acts 
will again consider only ISA pattern identification, i.e. 
proposing the candidate matches for a particular utter- 
ance form. Issues related to choosing between alter- 
natives are discussed in \[4\], along with a framework 
for using dialogue context to aid in this choice. The 
approach to ISA pattern identification suggested will 
be contrasted with two other computational ap- 
proaches, that of Moore, Levin, and Mann \[18,19\] and 
Allen, Cohen, and Perrault \[1,8,21\]. We start with a 
summary of each approach. 
The central structure in the process model of dia- 
logue developed by Moore, Levin, and Mann is called 
the dialogue game. Dialogue games are procedures 
that include steps for speech acts and their standard 
range of responses. Indirect speech act forms are 
related to these larger structures according to the gen- 
eral principle that any utterance that can establish the 
parameters of a dialogue game can serve as an ISA. 
For recognition, the correspondence between particu- 
lar ISAs and parameters is done by applying rule-like 
transformations using partial match and plausible in- 
ference techniques. Representations of utterances are 
placed in a pool of facts about the dialogue where 
correspondences are drawn by highly parallel 
"anarchic" control structures. 
The second computational approach to ISAs, that 
of Allen et al., focuses on the speech act planning 
process. Allen's work is most relevant here, because it 
deals in detail with ISA recognition. Alien introduces 
the notion of an obstacle, a type of condition in the 
speech act planning process that provides the subject 
matter for many varieties of ISAs. This approach 
appears to generate a more constrained set of possible 
ISA forms than the approach of Moore et al. and gives 
more basis for an explanation of the variety of forms. 
To draw the correspondence between ISAs and speech 
act plans, Allen et al. propose a general inference 
process guided by heuristics such as the principle that 
inference stops when a non-obvious condition is pro- 
posed as the topic of the ISA. 
These approaches and the one advocated here have 
in common the reliance on representation of actions to 
characteihze indirect speech acts. Allen, Cohen, and 
Perrault view the speech act as an independent unit; 
Moore, Levin and Mann relate ISAs to larger units of 
activity that have speech act components and that are 
defined according to the goals achieved by the speech 
acts. This difference between the approaches of Allen 
et al. and Moore et al. is, I think, primarily one of 
presentation rather than substance. The approach 
advocated here is a combination of the two perspec- 
tives. A complete system would need both the ability 
to handle the prototype speech act plus response se- 
quences (called core dialogue methods in \[4\]) and the 
ability to treat speech acts as basic building blocks 
within other sequences. By focusing on independent 
speech acts in this paper, I do not intend to rule out 
their incorporation within larger actions. 
A more substantive difference among the ap- 
proaches is the mechanism envisioned for drawing 
correspondences between individual ISAs and ISA 
patterns. Both of the approaches summarized above 
are theoretical in a traditional sense, in that they posit 
one mechanism powerful enough to account for any 
utterance, i.e., a mechanism powerful enough to han- 
dle the most difficult case. Coupled with the interest 
in maximizing power is the interest in maximizing sim- 
plicity; redundancy in the representation structure is 
not expected or exploited. 
In contrast, the proposals in this paper are motivat- 
ed by an "appropriate technology" view of ISA pat- 
tern identification. From this perspective, ISA pat- 
terns are assumed to be particularly adapted to com- 
munication, so that identifying candidate ISA patterns 
is not typically a general problem solving process. (I 
emphasize here pattern identification; choosing be- 
tween the alternative candidates identified appears to 
be a more open-ended process.) Given these assump- 
tions, the search is for a way to identify the most fre- 
quently used ISA forms simply, short of full-blown 
problem solving. The solution could include a hier- 
archy of processing strategies, differentiated to handle 
different levels of complexity. 
The descriptive model presented in the preceding 
sections relates to this philosophy on two counts: 
matching processes and the choice of levels of repre- 
sentation. Each is considered in turn. 
Section 5 described several different types of match 
between particular ISA representations and patterns: 
first, those matches using only predefined classification 
links in the knowledge base; second, those requiring 
evaluation of representations, possibly augmented by 
contextual information, to establish classification links; 
and, third, those using definition and method compo- 
nent links, again with or without the use of additional 
contextual information. While these distinctions can 
be used to guide a general inference mechanism, they 
could also be used in the development of specialized 
matching strategies, to take advantage of properties of 
the representations and links involved. 
Along with the use of specialized processors for 
ISA pattern identification can come the use of special- 
ized, and to an extent redundant, representations. 
This is most evident in the preceding pages in the dis- 
tinction between using the goal formation process as a 
conceptual organization of ISAs (and, hence, to an 
extent as an explanation) versus its use as a direct 
basis for drawing correspondences with individual 
ISAs. The ISA patterns assumed are at least three 
levels removed from any actual goal formation proce- 
dure: the use of maxims is an abstraction of the proce- 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 161 
Gretchen P. Brown Characterizing Indirect Speech Acts 
dure; generalized rules are based on maxims; and then 
ISA patterns are produced by applying rules to indi- 
vidual speech acts. This is in contrast to plan deduc- 
tion of Allen et al., which uses only very general rules 
coupled with the representations of the plan deduction 
process. Similarly, what was called the better- 
knowledge principle was "precompiled" into rules, 
rather than combined with more general rules by infer- 
ence. The thrust of the effort is to push ISA patterns 
to a level as close as possible to the representations of 
particular ISAs; in fact, in many cases this paper has 
not gone as far as possible, and I think, as ultimately 
desirable, in producing highly specific ISA patterns. 
This representational style is expected to have three 
effects. First, for many cases, it avoids problems in- 
herent in general inference processes of controlling the 
direction of inference toward the "interesting" cases. 
Second, the more specialized the patterns, the simpler 
the individual match processes, and the more forms 
can be handled by cheaper processes. Third, the vari- 
ous ISA patterns give a natural place to associate in- 
formation about idiomaticity and specialized informa- 
tion about implications of ISA choice. 
Note that these various mechanisms and represent- 
ations cannot be introduced arbitrarily. To be effec- 
tive, they must be chosen based on an understanding 
of the structure of indirect speech act classes, i.e. on 
an appropriate descriptive theory. This brings us back 
to the original claims of the paper; it is hoped that the 
proposals made are a step toward such a theory. 
Finally, it should be emphasized that the computa- 
tional apparatus sketched here complements, rather 
than seeks to replace, a generalized problem solving 
mechanism for ISA pattern identification. The hy- 
pothesis is that only a relatively small proportion of 
ISAs require the more general (and more expensive) 
mechanism. It is possible that the use of redundant 
mechanisms and representations can lead to good com- 
putational solutions to the problem of modelling a 
large body of indirect speech acts. 
Appendix. Indirect Forms for Sample Speech Acts 
• ask 
propositional content: some question 
performative: I ask you ... 
other direct form: 
<interrogative> e.g., Where's the mustard? 
principal intended effect: that P2 tell P1 the answer to 
the question in the propositional content 
Rule NECESSARY-ASSERT: 
I have to ask you where the mustard is. 
Rule NECESSARY-ASK: 
Do I need to ask you where the mustard is? 
Rule EQUI-ASK: 
Did I ask you where the mustard is? 
Rule FUTURE-EFFECT-ASK: 
Do you intend to tell me where the mustard is? 
Rule PAST-EFFECT-ASK: 
Did you tell me where the mustard is? 
Rule DESIRABLE-ASSERT: 
I'll be able to finish these sandwiches if you tell 
me where the mustard is. 
Rule DESIRABLE-ASK: 
Will you feel better if you tell me where the mus- 
tard is? 
Rule UNDESIRABLE-ASK: 
Will you be angry if I ask you where the mustard 
is? 
Precondition-Based Examples 
I. P1 wants to know the answer to the question. 
(Want here and in IV implies that P1 does not al- 
ready know the answer. The case where P1 does 
know and merely wants to know if P2 knows -- and 
where P2 knows that P1 knows -- is classed as an- 
other speech act. Know is considered to be a re- 
stricted form of believe; while anything can be be- 
lieved, only facts can be known. For ask, the 
"fact" is that some proposition is the answer to the 
question.) 
Rule P1-ASSERT: 
I want to know where the mustard is. 
II. P1 believes that P2 can tell the answer to the ques- 
tion. 
(Tell is used here and below to mean "utter a repre- 
sentative"; see Searle \[26\].) 
Rule UNMARKED-ASK: 
Can you tell me where the mustard is? 
Rule UNMARKED-ASSERT: 
You can tell me where the mustard is. 
III. P1 believes that P2 is willing to tell the answer to 
the question. 
Rule P2-ASK: 
Would you be willing to tell me where the mus- 
tard is? 
IV. P1 wants P2 to tell P1 the answer to the question. 
Rule P1-ASSERT: 
I'd like you to tell me where the mustard is. 
V. P1 believes that P2 has some obligation (a role 
obligation, authority obligation, or general obligation 
to be cooperative) to P1 to tell P1 the answer to the 
question. 
Rule UNMARKED-ASK: 
? Should you tell me where the mustard is? 
(Although it is possible to construct contexts in 
which this form can be used, it seems to be 
only marginal. Forms such as "Shouldn't you 
162 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characterizing Indirect Speech Acts 
tell me ...?" and "Don't you think you should 
tell me...?" are far more common. Perhaps this 
is because the "should" form is too neutral 
with respect to the obligation. To the extent 
that the obligation is motivated by Pl's wants 
or needs, then P1 defines the obligation. Even 
for other obligations, situations are scarce in 
which P1 can reasonably be presented as neu- 
tral about the existence of the obligation. In 
most cases, to successfully carry out the speech 
act, P1 must use a form that conveys Pl's be- 
lief that the obligation exists.) 
Rule UNMARKED-ASSERT: 
You ought to tell me where the mustard is. 
II-V together: 
Rule COMPOSITE-REQUEST: 
Tell me where the mustard is. 
Rule COMPOSITE-ASK: 
Will you tell me where the mustard is? 
• state 
propositional content: some proposition that P1 be- 
lieves to be open to confirmation against what P1 
believes is commonly held to be reality 
(This is contrasted with opinions, e.g., judgments 
about tastes, which are assumed to be conveyed 
by a different type of speech act.) 
performative: I state that ... 
other direct form: <declarative> e.g., Your candidate 
is a convicted felon. 
principal intended effect: that P2 come to know the 
proposition at the same level of detail and certainty as 
P1 
Rule NECESSARY-ASSERT: 
I have to tell you that your candidate is a convict- 
ed felon. 
Rule NECESSARY-ASK: 
Do I need to tell you that your candidate is a 
convicted felon? 
Rule EQUI-ASK: 
Has anybody told you that your candidate is a 
convicted felon? 
Rule FUTURE-EFFECT-ASK: GAP 
(Once a fact is mentioned, inquiry about future 
knowledge of that fact is irrelevant. This rules 
out forms such as "Will you hear that...?" and 
"Will you know that ...?") 
Rule PAST-EFFECT-ASK: 
Did you hear that your candidate is a convicted 
felon? 
Rule DESIRABLE-ASSERT: 
It's important that you hear that your candidate is 
a convicted felon. 
Rule DESIRABLE-ASK: 
? Is it helpful for you to hear that your candidate 
is a convicted felon? 
(The stative form "Is it helpful for you to know 
that...?" is much more acceptable. This form 
would be derived using DESIRABLE-ASK and an 
implicit-action rule. See Section 5 for general 
discussion.) 
Rule UNDESIRABLE-ASK: 
Will you be angry if I tell you that your candidate 
is a convicted felon? 
Precondition-Based Examples 
I. P1 believes that some proposition is a fact. 
Rule P1-ASSERT: 
I think that your candidate is a convicted felon. 
II. P1 believes that P2 does not know the proposition 
at the same level of detail and certainty that P 1 does. 
(The mention of "level of detail" here is motivated 
by an interest in including statements which could 
otherwise be mistakenly classed as redundant. For 
example, if P2 knows that it is raining, then the 
statement "It's raining" should be a violation of 
precondition II; a statement such as "It's pouring," 
however, should not.) 
Rule UNMARKED-ASK: 
Are you unaware that your candidate is a con- 
victed felon? 
Rule UNMARKED-ASSERT: 
You don't know that your candidate is a con- 
victed felon. 
III. P1 wants P2 to know the proposition at the same 
level of detail and certainty that P1 does. 
Rule P1-ASSERT: 
I want you to know that your candidate is a 
convicted felon. 
IV. P1 believes that it is in Pl's, P2's, or someone 
else's interest that P2 know the proposition at the 
same level of detail and certainty that P1 does. 
Rule UNMARKED-ASK: 
Should you know that your candidate is a con- 
victed felon? 
Rule UNMARKED-ASSERT: 
You should know that your candidate is a con- 
victed felon. 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 163 
Gretchen P. Brown Characterizing Indirect Speech Acts 
• offer 
propositional content: some action that P1 believes 
will be of benefit to P2 
performative: I offer you ... 
other direct form: none 
principal intended effect: that P2 accept Pl's commit- 
ment to take responsibility for the action in the propo- 
sitional content 
Rule NECESSARY-ASSERT: 
? I must offer you a ride to the airport. 
(In general, necessity alone is not considered to 
be enough to motivate an offer, although in prac- 
tice, of course, it may be the sole motivation. 
The propositional content specification of offer 
includes the notion of benefit to P2, so P1 is ex- 
pected to have the well-being of P2 in mind. The 
statement of necessity alone clashes with this ex- 
pected benevolence. The only way that this ex- 
ample form could be used for a sincere offer is if 
must is used in the same way as in the polite offer 
cited by R.Lakoff, "You must have some cake.") 
Rule NECESSARY-ASK: 
?Do I need to offer you a ride to the airport? 
(Beyond the considerations noted for the 
NECESSARY-ASSERT example, this form seems 
to be marginal due to the conflict between its 
angry connotations and the level of politeness 
involved in an offer.) 
Rule EQUI-ASK: 
Has anybody offered you a ride to the airport? 
Rule FUTURE-EFFECT-ASK: GAP 
(This gap is explained by the fact that the princi- 
pal intended effect for offer can be brought about 
only by the speech act; there is no independent 
means of achieving it.) 
Rule PAST-EFFECT-ASK: 
Have you already accepted a ride to the airport? 
Rule DESIRABLE-ASSERT: 
I'd feel a lot better if you'd accept a ride to the 
airport. 
Rule DESIRABLE-ASK: 
? Will you stop worrying if you accept a ride to 
the airport? 
(An elaboration of this rule may be warranted, 
since a form that explicitly names the speech act 
is much more acceptable, e.g., "Will you stop 
worrying if I offer you a ride to the airport?" It is 
not clear, however, exactly how to proceed, since 
comparable "explicit speech act" forms for request 
and suggest do not seem to exist.) 
Rule UNDESIRABLE-ASK: 
Will you be offended if I offer to loan you some 
money? 
Precondition-Based Examples 
I. P1 wants to take responsibility for the action. 
Rule P1-ASSERT: 
I want to drive you to the airport. 
II. P1 believes that P1 can take responsibility for Pl's 
part of the action. 
Rule UNMARKED-ASK: 
Can I drive you to the airport? 
Rule UNMARKED-ASSERT: 
I can drive you to the airport. 
III. P1 is willing to take responsibility for Pl's part of 
the action. 
Rule P1-ASSERT: 
I'm more than willing to drive you to the air- 
port. 
IV. P1 wants P2 to perform some action that comple- 
ments Pl's part of the action. 
(Examples of complementary actions would be 
physically taking food offered by a hostess or get- 
ting into a car and sitting in response to an offer of 
a ride from a friend. A general way to refer to P2's 
performance of a complementary action in response 
to an offered action is to say that P2 accepted, e.g., 
"Jane thanked Paula and accepted the gift.") 
Rule P1-ASSERT: 
I want you to accept a ride to the airport. 
V. P1 believes P2 can perform some action that com- 
plements Pl's part of the action. 
Rule UNMARKED-ASK: 
Can you accept a ride to the airport? 
Rule UNMARKED-ASSERT: 
You can accept a ride to the airport. 
VI. P1 believes that P2 would be willing to perform 
some action that complements Pl's part of the action. 
Rule P2-ASK: 
Would you be willing to accept a ride to the 
airport? 
VII. P1 believes that P2 has an obligation (to "be 
cooperative") to P1 to perform some action that com- 
plements Pl's part of the action. 
(It is generally in P2's interest to accept an offer, 
and so one of the obligations involved in accepting 
an offer is P2's obligation to further his or her own 
self interest. Beyond, this, however, P2 has an obli- 
gation to help further P1 's goals by virtue of a gen- 
eral social obligation to be cooperative. In accept- 
ing an offer, P2 is enhancing Pl's image as a benev- 
olent person, Pl's satisfaction in giving, etc. By 
accepting, then, P2 is furthering Pl's goals and be- 
ing "cooperative.") 
Rule UNMARKED-ASK: 
? Should you accept a ride to the airport? 
(See discussion for ask V.) 
Rule UNMARKED-ASSERT: 
You must accept a ride to the airport. 
164 American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 
Gretchen P. Brown Characterizing Indirect Speech Acts 
VIII. P1 believes that P2 has an obligation to P2 (by 
virtue of P2's own self-interest) to perform some ac- 
tion that complements Pl's part of the action. 
Rule UNMARKED-ASK: 
? That suitcase is heavy. Should you let me 
drive you to the airport? 
(See discussion for ask V.) 
Rule UNMARKED-ASSERT: 
That suitcase is heavy. You should let me drive 
you to the airport. 
IV-VII together: 
Rule COMPOSITE-REQUEST: 
Please accept a ride to the airport. 
Rule COMPOSITE-ASK: 
Will you accept a ride to the airport? 
• suggest 
propositional content: an action 
except for: actions in which P1 and P2 share com- 
mon agency 
(In excluding actions where P1 and P2 share com- 
mon agency, I am merely arguing for a separate 
type of speech act, e.g., suggest-common-action, to 
cover such cases.) 
performative: I suggest ... 
other direct forms: 
1. What about <action>? e.g., What about join- 
ing the Marines? 
2. How about <action>? e.g., How about joining 
the Marines? 
principal intended effect: that P2 consider taking 
responsibility for the action in the propositional 
content. 
Rule NECESSARY-ASSERT: 
I must suggest that you join the Marines. 
Rule NECESSARY-ASK: 
Need I suggest that you join the Marines? 
Rule EQUI-ASK: 
Has anyone suggested that you join the Ma- 
rines? 
Rule FUTURE-EFFECT-ASK: 
Are you thinking about joining the Marines? 
Rule PAST-EFFECT-ASK: 
Have you considered joining the Marines? 
Rule DESIRABLE-ASSERT: 
I'd be pleased if you'd consider joining the Ma- 
rines. 
Rule DESIRABLE-ASK: 
Would your parents be happy if you considered 
joining the Marines? 
Rule UNDESIRABLE-ASK: 
Would you be offended if I suggested that you 
join the Marines? 
Precondition-Based Examples 
I. P1 wants P2 to consider taking responsibility for 
the action. 
Rule P1-ASSERT: 
I want you to think about joining the Ma- 
rines. 
II. P1 believes that P2 can consider taking responsi- 
bility for the action. 
Rule UNMARKED-ASK: 
Could you think about joining the Marines? 
Rule UNMARKED-ASSERT: 
You could think about joining the Marines. 
III. P1 believes that P2 is willing to consider taking 
responsibility for the action. 
Rule P2-ASK: 
Are you willing to consider joining the Ma- 
rines? 
IV. P1 believes that P2 has an obligation (to "be 
cooperative") to P1 to consider the action. 
(The "be cooperative" obligation is similar to that 
for offer VII. The obligation arises from the fact 
that a goal of P1 is involved in a suggest, via pre- 
condition I.) 
Rule UNMARKED-ASK: 
? Should you think about joining the Ma- 
rines? 
(See discussion for ask V.) 
Rule UNMARKED-ASSERT: 
You must think about joining the Marines. 
V. P1 believes that P2 can take responsibility for 
the action. 
Rule UNMARKED-ASK: 
Can you join the Marines? 
Rule UNMARKED-ASSERT: 
You can join the Marines. 
VI. P1 believes that P2 is willing to take responsibil- 
ity for the action. 
Rule P2-ASK: 
Are you willing to join the Marines? 
VII. P1 believes that there are some reasons why 
the action is desirable. 
Rule UNMARKED-ASK: 
Would it be good for you to join the Ma- 
rines? 
Rule UNMARKED-ASSERT: 
You'd be a credit to your sorority if you 
joined the Marines. 
American Journal of Computational Linguistics, Volume 6, Number 3-4, July-December 1980 165 
Gretchen P. Brown Characterizing Indirect Speech Acts 
VIII. P1 believes that P2 has an obligation to P2 
(by virtue of P2's own self-interest) to consider 
taking responsibility for the action. 
Rule UNMARKED-ASK: 
You need a new experience. Should you join 
the Marines? 
Rule UNMARKED-ASSERT: 
You need a new experience. You should join 
the Marines. 
I-IV together: 
Rule COMPOSITE-REQUEST: 
Think about joining the Marines. 
Rule COMPOSITE-ASK: 
Will you consider joining the Marines? 
Acknowledgements 
This paper builds on work in knowledge repre- 
sentation done by William A. Martin and members 
of the Knowledge Based Systems Group at the 
M.I.T. Laboratory for Computer Science. I am also 
grateful to William Mark, Candace Sidner, Peter 
Szolovits, James Weiner, and the referees for many 
helpful comments. Special thanks to Michael 
McCord and George Heidorn for substantial con- 
tributions to the presentation. 

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