THE SIAMESE TWINS:
INVENTIO AND DISPOSITIO
Mark L. Knapp
University of Wisconsin in Milwaukee
James C. McCroskey
Pennsylvania State University
Traditionally rhetorical literature has reflected a distinct separation
of inventio and dispositio. One of the earliest statements supporting this
view is found in Book I of De Inventione. Cicero tells us that:
. . . when the point for decision and the arguments which must be devised
for the purpose of reaching a decision have been diligently discovered
by the rules of art, and studied with careful thought, then, and not until
then, the other parts of the oration are to be arranged in proper order.
This assumption, which is also frequently made today, suggests that the inventive process should continue until the speaker amasses a larger number of arguments, and then dispositio should ensue.
This separation, however, does not seem to be as distinct as one might be led to believe. In audience-centered rhetoric there is substantial interaction of inventional and dispositional thought processes. It is our purpose to specify this interaction and to suggest that for persuasive communication a complete dichotomization of inventio and dispositio is theoretically unsound and pedagogically impractical.
First, let us review some of the mental activities usually considered to be components of inventio and dispositio. Then we will be able to specify more clearly the interrelationship involved.
Our discussion will utilize terminology based on the model of argument
developed by the British logician, Stephen Toulmin. Three of these terms
need to be explained briefly: (1) data--informational statements believed
by an audience and employed by a speaker to secure belief in another statement;
(2) claim--an explicit conclusion that a speaker wants an audience to accept;
and (3) warrant--an inferential statement which links the data to the claim.
INVENTIO AND DISPOSITIO
A speaker's first concern in inventio is to determine what reaction
he wants to evoke from his audience. In short, what claim does he desire
them to accept? All inventio must be based upon his answer to that question.
He must discover data and warrants that will enable him to invent arguments
that will secure audience acceptance of his central idea. In essence, his
first concern is to determine his central argument. This is the argument
that culminates in the claim which represents his specific purpose for
speaking. In most cases the speaker will find it necessary to develop a
series of interrelated arguments in order to gain acceptance of this ultimate
claim. These will develop as branches from the basic argument and the need
to invent them will become apparent through audience analysis and hypothesizing
audience reaction to arguments or portions of arguments. It must be stressed
that all inventio must be based on continuing analysis of the audience.
Each argument and each datum, warrant, and claim should be checked against
an hypothesized reaction to that argument or portion of an argument by
the specific audience form whom it is being invented. The importance of
this point will be considered later, but now let us take an example to
further clarify what we mean:
The speaker is a superintendent of schools. His audience is the local
school board. His purpose, his ultimate claim, is that the board should
purchase television equipment for the classrooms in the local high school.
His invention process must begin from here. He must ask, "What data
and warrants can be used to establish this claim?" He could possibly
base his argument on his own ethos. Such an argument might go something
like this: "I say that TV equipment should be purchased for the local
high school (data), and since I am a credible source (warrant) therefore,
we should purchase the equipment (claim)." He must then analyze his
audience to determine whether they would be likely to accept such a claim
based exclusively on his ethos. If he hypothesizes that they would not,
he must strive to invent another argument. He may conclude that the audience
is primarily motivated by two factors--how education in the school can
be upgraded and how costs can be kept down. If he determines this, he will
have found two possible warrants of a motivational nature which can be
used. His basic arguments then might be something like this: "TV will
improve education (data) and since we are motivated by our desire to improve
education (warrant) we should buy the TV (claim)," and "TV will
cut costs (data) and since we are motivated by our desire to cut costs
(warrant) we should buy the TV (claim.)
From here we can see how the rest of the inventio process would proceed.
The speaker would look at the data in the above arguments as claims and
proceed to invent arguments to establish them. In each case, every part
of the argument is selected or rejected on the basis of an hypothesized
The mental operations involved in dispositio are not as easily described
in isolation. However, reasoning from the desired results of dispositio,
it seems that these ends can be met through three Ciceronian operations:
(1) selecting--the choosing of the materials to be included in the
speech; (2) arranging--the strategic maneuvering of arguments
to produce the desired effect; and (3) apportioning--the weighing
of the relative importance of materials to determine the amount of stress
they should receive in the speech.
INTERRELATION OF THE TWO
With the above mental operations of inventio and dispositio in mind,
let us examine that part of dispositional thinking which is closely interwoven
One can readily see that this dispositional process is also a vital
part of inventio. In fact, much of inventio is simply a matter of selection,
based on audience analysis. Each datum and each warrant is selected on
the basis of an hypothesized audience reaction to it and further data and
warrants are selected as validation and/or support for those selected previously.
In short, when inventio is complete, few problems of selection remain to
be considered. Only if we treat inventio as being divorced from audience
considerations can it be otherwise. If inventio is the creation of arguments
in a vacuum, then selection can follow it. However, if inventio is based
on the audience, selection is an integral part of the process.
The mental process of arranging is also partially completed during inventio.
The main factor determining the strategic importance of an argument is
where the argument leads. If an argument is invented to validate data,
then it must be presented in the speech in such a manner as to lead to
that end. This rhetorical process is similar to that of an engineer building
a bridge over a river. The engineer must know the nature of both banks
and then plan a bridge which will lead from one to the other. Similarly,
the speaker must know what his audience's present position is on the issue
to be considered and what he wants it to be. Then he builds a speech that
will lead to that end. The wisdom of an engineer would be doubtful indeed
if he were to build six spans and ninety-six supports for a bridge and
then try to figure out how to arrange them for functional use. Each span
of a bridge is planned and built to fit in a certain place so as to connect
properly with the spans on either end of it, as are the supports for the
structure. The arguments of a speech need to be planned and built in the
To understand how this dispositional process interrelates with inventio we must remember that inventio is predicated on the need for argument to gain acceptance of claims. The speaker must hypothesize the probable audience response to an idea to determine how far to go in the invention of argument leading to that idea. This is actually an apportioning decision. He is deciding whether, with this particular audience, he will need one, two or seven arguments to gain acceptance of the idea; or whether he will need one, two or twenty pieces of data in a given argument. If the speaker wishes to leave all apportioning until the completion of inventio, he may never determine that he is ready to conclude inventio--at best he will have no accurate guide upon which to base a decision to terminate at a given point. He will probably find he has invented either too many or too few arguments or materials when he decides to apportion.
Thus the lines seem to be far from sharply drawn between how one thinks during inventio and how one thinks during dispositio. Rather than being two separate processes, inventio and dispositio are complementary parts of the same process--the process of analyzing the audience and developing a speech to evoke a predetermined reaction from that audience. If one chooses to consider inventio and dispositio as two completely separate and distinct rhetorical functions, he chooses to consider rhetoric apart from audience.
Although, as we have noted above, we cannot completely dichotomize these functions, we can make some distinctions. Barrett Wendell, a 19th Century professor of English at Harvard, made a distinction between "preview" and "review" dispositional thought processes. Thus far, we have been discussing primarily the "preview" operations--those inextricably bound to inventio.
Although one is still concerned with selecting, arranging and apportioning as he "reviews" the products of his original or inventional thoughts, we must note that the mind is now functioning with these processes at a different level. The reviewing process provides a more definitive focus for dispositional thought. There are obvious differences in what one has to select, apportion and arrange. For instance, a question of arrangement might now take this form: "Should the claim be stated before the data are presented or after?" A question of selection might now be: "Since this speech is too long for the time allowed, which evidence can I omit?" The mind is now manipulating information already derived from similar processes at an inventional level.
The most important thing to remember is that dispositional thought occurs
at two points in the development of audience-centered rhetoric. It may
take place during inventio as a "preview" process and again as
a distinguishably separate process in the "review" stage. While
dispositio has a function outside inventio, if the discourse is to be audience-centered,
the function of dispositio within inventio must not be overlooked.
TEACHING THE INTERRELATION
The fact that dispositio cannot be divorced from inventio has pedagogical as well as theoretical implications. For instance, one of the tasks of the speech pedagogue is to evaluate the dispositional aspects of a speech. Although the point is conspicuously simple, it seems worthwhile to point out that what often appears to be a poor job of organization may actually be a manifestation of an insufficient grasp of inventional processes. A failure to correctly identify the audience's role in relation to a particular type of speech; the perfunctory use of a Topic System; a non-specific purpose; all these inventional operations may be manifested as poor organization. Thus, in some cases, the critical comment "poor organization" ignores the real problem.
Another facet of criticizing dispositio in student speeches is concerned with the thought processes involved. If we are to assume that dispositio includes selecting, arranging, and apportioning, is it not likely that a student may be deficient in one or perhaps two of these while performing the other(s) satisfactorily? He may select the proper arguments and apportion them correctly, but make a gross error in arrangement. Or, as happens more frequently, he may select the proper arguments and arrange them correctly, but over stress the problem to the detriment of the solution. In such cases, the "poor organization" comment does not accurately specify the student's problem. The instructor must determine the specific thought process that is faulty and bring it to the student's attention.
It seems tenable that the primary pedagogical focus should be on the "preview" aspects of dispositio. It is neither practical nor desirable to de-emphasize the dispositional processes of selecting, arranging and apportioning in audience-centered inventio. One might suggest that telling students to gather their ideas and materials and then organize their speeches retards their rhetorical growth. At the very least, the instructor must be cognizant of the fact that treating dispositio as a purely "review" process fosters material-centered rather than audience-centered rhetoric. Whether we consider our rhetoric to be "Aristotelian," "Ciceronian," or "Modern," there are few among us who would prefer material-centered rhetoric to that which is audience-centered.
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