participants implement for achieving their opposite
communicative goals and their movement in
communicative space. Section 4 discusses the
analysed dispute and proposes a communicative
strategy that can be effective in a computer system
for argumentation. In section 5 we draw conclusions.
2 A MODEL OF DISPUTE
2.1 Components of the Model
Let us consider a dialogue between two participants
A and B (humans or artificial agents) in a natural
language (Koit and Õim, 2013; 2014b). Let the
communicative goal of A be “B decides to do the
action D”. A has a partner model at his disposal – an
image about B – which gives him an opportunity to
believe that B will agree to do the action. In
constructing his first turn, A plans the dialogue acts
(e.g. proposal, request, etc. depending on his partner
model) and determines their verbal form (i.e. the
utterances). The partner B interprets A’s turn and
generating her response, she triggers a reasoning
procedure in her mind in order to make a decision –
to do D or not. In the reasoning process, B weighs
her resources, positive and negative outcomes of
doing D and finally, she makes a decision. Then she
in her turn plans the dialogue acts (e.g. agreement,
refusal, refusal with argument, etc.) and their verbal
form in order to inform A about her decision. If B
agrees to do D then the dialogue finishes (A has
reached his communicative goal). If B’s response is
refusal then A must change his partner model (which
did not correspond to the reality because A supposed
that B will agree to do D) and he has to find out new
arguments to convince B to make the decision.
B can add arguments to her refusal. These
(counter)arguments give information to A about the
reasoning process that brought B to the (negative)
decision.
Then A has to find a new argument for doing D
by B and the process continues in a similar way.
2.1.1 Reasoning Model
Our reasoning model consists of two parts: (1) a
model of human motivational sphere; (2) reasoning
procedures (Koit and Õim, 2014b). In the
motivational sphere of a reasoning person some
basic factors can be found that regulate reasoning
about doing an action D. We call these factors
WISH-, NEEDED- and MUST-determinants,
respectively. First, a subject has a wish to do D if the
pleasant aspects of D outweigh the unpleasant ones;
second, doing D is needed for the subject if the
useful aspects of D outweigh the harmful ones; and
third, a subject must to do D if not doing implies
some punishment.
We represent the model of motivational sphere
of a subject by the following vector of ‘weights’
(with numerical values of its components):
w = (w(resources), w(pleasant),
w(unpleasant), w(useful), w(harmful),
w(obligatory), w(prohibited),
w(punishment-do), w(punishment-not)).
In the description, w(pleasant), etc. mean the
weight of pleasant, etc. aspects of D; w(punishment-
do) – weight of punishment for doing D if it is
prohibited, and w(punishment-not) – weight of
punishment for not doing D if it is obligatory. Here
w(resources) = 1, if subject has the resources
necessary to do D (otherwise 0, i.e. we suppose that
all the needed resources either exist or not);
w(obligatory) = 1, if D is obligatory for the
reasoning subject (otherwise 0); w(prohibited) = 1, if
D is prohibited (otherwise 0). The values of other
weights can be non-negative natural numbers.
Although in reality people do not operate with
numbers but use words for characterising different
aspects of an action (e.g. extremely useful, not much
useful, neither useful nor harmful, etc.), the
existence of certain scales also in human everyday
reasoning is apparent.
The second part of the reasoning model consists
of reasoning procedures that supposedly regulate
human action-oriented reasoning. A reasoning
procedure depends on the determinant which
triggers it (in our model, WISH, NEEDED or
MUST). Every reasoning procedure represents steps
that the subject goes through in his/her reasoning
process; these consist in computing and comparing
the summarized weights of different aspects of D;
and the result is the decision: to do D or not (Koit
and Õim, 2013).
We use two different vectors of weights in our
model of dispute: w
B
(B’s idiosyncratic model which
represents B’s actual evaluations of D’s aspects) and
w
AB
(the partner model – A’s beliefs concerning B’s
evaluations).
2.1.2 Communicative Space
Communication between two participants can be
different: collaborative or confrontational, polite or
impolite, friendly or unfriendly, etc. Moreover, a
dialogue which has started violently can finish
peacefully if the participants achieve a compromise,
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