Accepting the truth of a story about the facts of a criminal case
Bart Verheij
Artificial Intelligence, University of Groningen
Floris Bex
Centre for Law and ICT, University of Groningen
Abstract
Crombag, Van Koppen and Wagenaar have proposed the anchored narratives
theory as a tool for establishing and identifying the facts of a criminal case. The
theory emphasises the role of stories in reasoning about the facts, and the pivotal
function of anchoring generalisations. Here the anchored narratives theory isreconstructed in terms of semi-formal argumentation schemes, a method borrowed
from recent research crossing the fields of argumentation theory and artificial
intelligence. Hence we provide an elaboration and refinement of the anchorednarratives theory, and are able to show how stories can play an explicit role inreasoning about the facts. In the present approach, not only the elements of stories
are part of argumentation, but also stories as wholes. We argue that accepting one
story (typically about the facts of the crime) can depend on the acceptance of otherstories (typically about pieces of evidence) and that a more elaborate theory ofstory structures is required, one in which other story structures than only one forintentional crime is distinguished.
1

Introduction

One task in legal decision making is to decide about the facts of a case on the basisof the available evidence. This task is not always easy1; often the evidence in acase points in different directions, for example, when witnesses contradict eachother. Determining what exactly can be concluded from the evidence is also not aneasy or trivial task. For instance, when an accused's footprints are found on thescene of the crime one is tempted to assume that the accused has committed thecrime, while the footprints by themselves only point in the direction of the accused
being present.
Reasoning about the facts of a case has been studied in several disciplines.
For example, in the psychology of law Crombag, Van Koppen and Wagenaar haveproposed the anchored narratives theory (1992, 1994; 1993): legal decisions about
the facts of a case are analyzed in terms of structured stories anchored in common
knowledge.
This research raised a significant amount of discussion, both among legal
professionals in the Netherlands and among evidence theorists. The debate in thelegal profession was not a surprise, as it was one of the goals of the authors. Theirstyle, described as 'in some respects closer to 'higher journalism' than to 'scientific'
publications' (Twining 1995, p. 109), was intentionally provocative as Crombag,
Van Koppen and Wagenaar aimed at exposing a failure of the legal system: theyargue that too often errors occur when deciding about the facts in criminal cases.
Their work can be regarded as a form of social criticism in that it aims to reduce thenumber of miscarriages of justice, or 'dubious cases' as they call them.
Perhaps somewhat more of a surprise was the critical - albeit civilized reception of the anchored narratives theory among evidence theorists (e.g.,
Twining 1995, Den Boer 1995). Among the points of criticism raised were: an
1

Whether the task of deciding about the facts is well-defined (considering the
problematic, but legally relevant, distinction between questions of fact and of law)is a matter that we ignore here.

1

imprecise use of terminology, especially concerning the central notions of story andargument (Twining 1995, p. 109); the treatment of pieces of evidence as a story
instead of as a means of argument (Twining 1995, p. 110); the lack of distinction
between descriptive and prescriptive goals (Twining 1995, p. 108; Den Boer 1995,
p. 328-9), exemplified by the lack of distinction between empirical generalisations
and prescriptive rules; the presentation of too simple, over-generalized universal
rules of evidence (Twining 1995, p. 113); and an unclear role of on the one handcommonsense generic beliefs and on the other commonsense knowledge of
scenarios (Den Boer 1995, p. 334).2
One thread through these points of criticism is the allegedly insufficientprecision and detail of the presentation of the theory of anchored narratives thatformed the basis of Crombag, Van Koppen and Wagenaar's project. In the present
text this overarching point of criticism is used as a starting point; the goal is to givea treatment of the anchored narratives theory that does justice to the originaldescription by Crombag, Van Koppen and Wagenaar while increasing the precisionof its description. We do this by using a specific technique: the methodologicaldevelopment of a coherent set of semi-formal argumentation schemes (to be
explained below). Although the aim is to stay close to the original description the
result of this paper is necessarily a reconstruction, an interpretation. Certain
choices are made, some of them explicitly for reasons that will be explained, others
inadvertently by personal predisposition or biased reading. Also, by the choice of
method some themes are enlarged upon while others are neglected. For instance,
the method abstracts from procedural constraints, which nevertheless is a recurring
theme in the discussions by Crombag, Van Koppen and Wagenaar.
The method chosen is that of analyzing and developing argumentation
schemes as presented by Verheij (2003b). The method takes Walton's work onargumentation schemes (especially his 1996) as a starting point and is styled
towards formal techniques in the field of artificial intelligence and law (cf., e.g.,
Prakken 1997, Hage 2005). In the method, argumentation schemes are treated asa semi-formal generalization of the formal rules of inference of logic andargumentation schemes are specified in terms of their conclusion, premises,
exceptions and conditions of use.
By choosing this semi-formal method the paper connects to a suggestion
made by Crombag, Van Koppen and Wagenaar; when they contrast their theory
with logical inference theories, they allude to the possibility of extended logicalsystems that are better suited as models of legal decision making than thesubsumption model (1993, p. 22). Especially in the field of artificial intelligence andlaw such extended logical systems have been designed. Among the topics
addressed in these legal logics are exceptions, inconsistencies, gaps, contingent
validity and rule properties (see Sartor's comprehensive 2005 work for an overview
of the possibilities).
This text is a development of earlier work on reasoning with evidence,anchored narratives and argumentation schemes (Verheij 2000, 2003b; Bex et al.
2003; Bex, Prakken et al. 2007) in the context of the project 'Making sense ofevidence' (Bex, Van den Braak et al. 2007). Whereas previously we emphasized theformal modelling of defeasible arguments about story elements, we here use thesemi-formal approach of argumentation schemes and show how stories as wholes
can have an explicit role.
The rest of this text is organized as follows. In section 2, the theory ofanchored narratives is summarized. Section 3 is about dialectical argumentation
2

Twining (1999) has given a useful adapted and extended discussion of the pointsof agreement and disagreement between the anchored narratives approach and theschool that is inspired by Wigmore, with authors such as Anderson, Schum andTwining himself. Cf. also Anderson et al. 2005.

2

and argumentation schemes. Section 4 is the heart of this paper: it contains thereconstruction of the theory of anchored narratives in terms of argumentation
schemes. The resulting set of argumentation schemes is listed in an appendix.
Section 5 contains some concluding remarks.
2

Anchored narratives3

In their books Dubieuze zaken (1992, 1994, p. 61f.) and Anchored narratives(1993, p. 33f.), Crombag, Van Koppen and Wagenaar present the theory ofanchored narratives as a model of legal decision making. The starting point of thetheory is that proof in a criminal trial comes down to telling a good story. In thefollowing the theory of anchored narratives is summarized. More information about
the theory and many examples illustrating it can be found in the books mentioned.
In the theory of anchored narratives courts make two judgments in criminalcases in order to establish the facts. First, they determine whether the stories ofthe parties before them (i.e., the prosecution and the defence) are plausible. Herethe quality (or goodness) of the stories is at issue. Second, courts decide whether
the available evidence is sufficiently supported by facts. This is where the anchoringof stories is examined.
Crombag, Van Koppen and Wagenaar consider their theory to be a naturaldevelopment of earlier research on stories in legal psychology. In this research,stories provide the context that gives meaning to the individual elements of thestory. This can be illustrated by the following mini-story:
Peter fired a gun. George was hurt.
When one is told this mini-story, one is inclined to assume that George was hurt byPeter shooting the gun. This is however not an explicit part of the story, and can befalse.
Crombag, Van Koppen and Wagenaar base their discussion about the qualityof stories on earlier work by Bennett and Feldman and Pennington and Hastie.
According to Bennett and Feldman, a good story has a central action, to which allelements of the story are related. In the above example, the event that Peter fired
a gun explains the action that George was hurt. A good story does not have loose
ends. That is, in a good story the setting of the action unambiguously explains why
the central action occurred as it did. If not, there are elements missing from thestory, or there are contradictions.
Pennington and Hastie extended the theory by Bennett and Feldman; theyargue that in a good story, the central actions and their consequences can becausally explained by three types of factors: physical conditions, psychologicalconditions and goals. So a good story must contain the accused's motives and showthat the accused had the opportunity to commit the crime.
An experiment by Pennington and Hastie has shown that a set of evidence
in a case does not guarantee a unique outcome. It turned out that, in a case wherea person was killed, by different selections and evaluations of the evidence test
persons reached outcomes ranging from first-degree murder, through seconddegree murder and manslaughter, to self-defence. In another experiment,
Pennington and Hastie showed the influence of story order on verdicts. The party's
positions about the event that was to be explained, in this case that a dead person
was found, were presented to the test persons either in chronological story order,
or in random order, such as the order in which witnesses gave their testimonies. It
turned out that if a party's position was told in the chronological story order thetest person more easily followed that party's position in the verdict. If the3This section is adapted from Verheij (2000).

3

prosecution's position was given in chronological story order, while the defence's
position was told in random order, the accused was convicted in 78% of the cases.
If on the other hand the prosecution's position was given in random order and thedefence's in chronological story order, the accused was convicted in 31% of thecases. Crombag, Van Koppen and Wagenaar conclude that telling the story well ishalf the work.
Crombag, Van Koppen and Wagenaar claim that story anchoring is neededin order to justify why a story is taken to be true. For instance, the statement of apoliceman that he saw that Peter fired a gun at George, can support that Peter
indeed fired a gun at George. By itself, the evidence consisting of the policeman's
statement does not prove that Peter fired a gun at George. If the policeman's
statement is considered as proof, this is the result of the acceptance of the rule4
that policemen tell the truth. Rules need not hold universally; there can be
exceptions. No one believes that policemen always tell the truth, but many hold thebelief that policemen tell the truth most of the time. According to Crombag, Van
Koppen and Wagenaar, there are common-sense generally true rules that underlie
the acceptance or rejection of a piece of evidence as proof. They refer to such rules
as anchors.
Crombag, Van Koppen and Wagenaar note that different legal systems can
not only use different rules as anchors, but even opposites. They give the exampleof the assessment of confessions. Under English law, a conviction can be based only
on the accused's confession, while in Dutch law, additional evidence is required.
This suggests that the English use the anchoring rule that confessions are usuallytrue, and the Dutch the opposite rule that confessions are often untrue.
Since the rules used as anchors can have exceptions, it can be necessary toshow that a particular exception does not occur. Crombag, Van Koppen andWagenaar discuss the example of the truthfulness of witnesses (1993, p. 38). Even
if one assumes that witnesses normally tell the truth, the rule is not a safe anchor
when the witness has a good reason to lie. Additional evidence is required, forinstance, the testimony of a second witness. Even if both witnesses are unreliable
since they have good reasons to lie, it can be argued that when their testimonies
coincide the combined statements suffice as proof. The anchor would then be thatlying witnesses do normally not tell the same lies. There is however again an
exception: if the two testimonies are not independent, for instance since thewitnesses have conferred, the anchoring is again not safe.
In the theory of anchored narratives, stories are hierarchically structured.
The main story can consist of sub-stories that on their turn contain sub-sub-stories,and so on. The idea is that each sub-story is a further specification of the story or
one of its parts. In each sub-story, a rule is used as an anchor to connect one ormore pieces of evidence to the decision of the story or to a part of the decision. A
difficulty arises from the fact that the rules used as anchors often remain implicit.
Making the naïvely adopted rule explicit can lead us to reject it (1993, p. 38).
If one goes to a deeper level in the story hierarchy, the anchors will become
more and more specific, and as such safer. For instance, at a high level, theanchoring rule could be that witnesses normally tell the truth, while at a deeper
level it could be replaced by the rule that witnesses that have no good reason forlying normally tell the truth.
Figure 1 (adapted from 1992, 1994, p. 72, 1993, p. 39) illustrates thetheory of anchored narratives.

4

Some would prefer to speak of a generalisation because of the normative, eveninstitutional connotation of the term 'rule'.

4

StorySub-story

Sub-story

Sub-sub-story

Sub-sub-story

Knowledge of
the world,
commonsense rules

Figure 1: the theory of anchored narratives
The use of rules as anchors gives the theory of anchored narratives a deductive
element. A decision follows from the evidence on the basis of a general rule.
According to Crombag, Van Koppen and Wagenaar, anchoring is not equal tosubsuming under a rule, since rules can have exceptions (1993, p. 58).
Crombag, Van Koppen and Wagenaar use their theory of anchorednarratives in order to explain what they call dubious cases (or dubious convictions).
In their terminology, a criminal conviction is dubious if the District Court's verdict
was reversed by the Court of Appeals because of a different evaluation of theevidence, or if the defence attorney remained strongly convinced of his client's
innocence, even after (repeated) conviction (1993, p. 11). Thirty-five of suchdubious cases were obtained from criminal lawyers, or were selected from among
the cases in which one of the authors served as an expert witness. Crombag, Van
Koppen and Wagenaar claim that their set of cases supports the theory of anchorednarratives, since the anomalies that occur in the cases can only be explained bytheir theory.
As a spin-off of their work on dubious cases, Crombag, Van Koppen andWagenaar present ten universal rules of evidence (1993, p. 231f.):
1.
2.
3.
4.
5.
6.

7.
8.
9.
10.

The prosecution must present at least one well-shaped narrative.
The prosecution must present a limited set of well-shaped narratives.
Essential components of the narrative must be anchored.
Anchors for different components of the charge should be independent ofeach other.
The trier of fact should give reasons for the decision by specifying thenarrative and the accompanying anchoring.
A fact-finder's decision as to the level of analysis of the evidence should
be explained through an articulation of the general beliefs used asanchors.
There should be no competing story with equally good or better anchoring.
There should be no falsifications of the indictment's narrative and nested
sub-narratives.
There should be no anchoring onto obviously false beliefs.
The indictment and the verdict should contain the same narrative.

Obviously, these universal rules of evidence cannot be applied 'as is'. Wagenaar,
Van Koppen and Crombag are fully aware of this. For instance, with respect to rule
8, they explain that it is not necessarily clear what counts as a falsification andwhat not (p. 243-4). For further qualification of these universal rules of evidence,
the reader is referred to the original source (1993, p. 231f.).

5

3Modelling argumentation

In this section, we will discuss the modelling of argumentation, as relevant for the
rest of this paper. The discussion is informed by interdisciplinary research in thefields of argumentation theory, artificial intelligence and law (cf., e.g., Pollock 1995,
Prakken 1997, Hage 2005, Walton 2005, Walker 2007). Here we follow theapproach by Verheij (2003a, 2003b).5 For present purposes, we have skipped
formal detail. These can be found in the sources mentioned.
3.1

Toulmin's argument model

Toulmin (1958) introduced a model for the analysis of arguments that was richer
than the traditional logical scheme focusing on premises and conclusions. His model
has been and remains influential across a variety of disciplines (cf. Hitchcock &Verheij 2006). The model is shown in Figure 2. Datum and claim are analogues ofpremise and conclusion. Toulmin's original example used "Harry was born in
Bermuda" as datum and "Harry is a British subject" as claim. The warrant is a
generic inference license underlying the step from datum to claim. In the example:"A man born in Bermuda will generally be a British subject". The backing ("Thestatutes and other legal provisions so-and-so obtain") provides support for the
warrant. The rebuttal is a form of argument attack that allows argumentation
against the claim or the support for it (e.g., "Harry has become a naturalized
American"). Toulmin also included a qualifier, in order to make explicit thatarguments can lead to a qualified conclusion ("Presumably, Harry is a British
subject").
So, Q, C

D
Since
W

UnlessR
On account ofB

D for Datum
Q for Qualifier
C for Claim

W for Warrant
B for Backing
R for Rebuttal

Figure 2: Toulmin's argument model
3.2

Datum & claim

The basic, non-trivial form of argumentation consists of a reason that supports a
conclusion. In Toulmin's terminology: a claim is supported by a datum. In thepresent approach, in order for the claim to follow, two elements are needed: thedatum and the connection between the datum and the claim. Figure 3 gives agraphical representation of the three basic situations. On top, there is the situationin which the datum and the connection between datum and claim are assumed(indicated by the thick lines). As a result of these assumptions the claim ispositively evaluated (indicated by the bold font).
5This section is adapted from Verheij (2007).

6

It can occur that the datum is considered a possible reason for the claim,
while the datum itself is not assumed (see the middle of Figure 3). In other words,
the connection between datum and claim is assumed, but not the datum itself.
Then the datum and claim are each neither positively nor negatively evaluated,which is indicated by a regular, black font and a dotted border. When the datum is
not assumed, argumentation can naturally proceed by providing a reason for thedatum (turning the datum into the claim of a second datum/claim-pair).
The bottom of Figure 3 shows the situation where the datum is assumed,
but the connection between datum and claim is not. In that case, the datum ispositively evaluated, but the corresponding claim is not.
Harry was bornin Bermuda

Harry is a
British subject

Harry was born in
BermudaHarry is a British
subject

Harry was bornin Bermuda

Harry is a British
subject

Figure 3: A datum and claim
3.3

Warrant & backing

When the conditional connection between datum and claim is not assumed (as at
the bottom of Figure 3), a natural argumentative move is to specify the warrant
that gives rise to it. A warrant is a generalized inference license and can as such inordinary language be phrased as a rule sentence. In this connection, it is important
to distinguish between the following three:
A man born in Bermuda will be a British subject.
If Person was born in Bermuda, then Person is a British subject.
If Harry was born in Bermuda, then he is a British subject.
The first is the warrant, i.e., a generic inference license phrased as a rule sentence.
The second is the scheme of specific inference licenses related to it. It is phrased asa conditional sentence with a variable (Person). The third is a specific inference
license. It is one of the instances of the scheme preceding it. The first two (thewarrant and the associated scheme) are in a specific sense equivalent since either
expresses the warrant's core meaning as a generic inference license. However
obviously only the rule phrase occurs in ordinary language.
Figure 4 (top) shows a warrant that is assumed to hold and hence ispositively evaluated. As a result of the warrant, the connection between the original
datum and claim follows. When the warrant is not assumed (Figure 4, bottom), theconnection between datum and claim does not follow. Consequently, the claim does
not follow either and is not positively evaluated.
In such a case, a backing from which the warrant follows can be given as
support for the warrant. The result is that the claim becomes positively evaluatedagain (Figure 5).

7

Harry is a
British subject

Harry was bornin Bermuda

A man born in Bermuda
will generally be a
British subject

Harry is a British
subject

Harry was bornin Bermuda

A man born in Bermuda will
generally be a British
subject

Figure 4: Adding a warrant

Harry was bornin Bermuda
The statutes
and other legal
provisions soand-so obtain

Harry is a
British subject

A man born in Bermuda
will generally be a
British subject

Figure 5: The role of a backing
3.4

AttackThe strongest deviation from classical logical analyses of argument in Toulmin's
model is the idea of argument attack, in Toulmin's terminology: rebuttal.6 The
possibility of attack involves the defeasibility of arguments: an argument thatshows why a conclusion follows can by new information (counterreasons,
exceptions to a rule, etc.) become overturned. Technically, the effect isnonmonotonicity, i.e., it can occur that conclusions that initially follow are retracted
given additional information.
The basic form of attack and its effect on argument evaluation is most easily
illustrated in a situation with only a datum and a claim, and no warrant or backing.
Figure 6 shows the effect of an attack against the connection between datum andclaim. At the top, the attacking reason is not assumed (but its undercutting effect isassumed, as is shown by the thick red arrow with a diamond end); hence the claim
is still positively evaluated. At the bottom, the attacking reason is assumed, andtherefore blocks the connection between datum and claim. As a result, the claim is
no longer positively evaluated.

6

Pollock (1995) has distinguished two kinds of argument attack, viz. rebutting andundercutting defeaters. Considering his examples, Toulmin's rebuttals can include
both kinds.

8Harry is a
British subject

Harry was bornin Bermuda

Harry has become anaturalized American

Harry is a
British subject

Harry was bornin Bermuda

Harry has become anaturalized American

Figure 6: An attacking reason (no warrant)
3.5

Reinstatement

An important phenomenon that can occur when argumentation is defeasible isreinstatement. This occurs when a conclusion follows, then by additional
information no longer follows, but subsequently - when even more information isadded - follows again. For instance, assume an unlawful act case in which someone
has broken a window. As a result, it can at first be argued that he has an obligation
to pay for the damages because of breaking the window. That conclusion no longer
follows when this argument is attacked by a ground of justification, e.g., because
the breaking of the window allowed the saving of a child in the burning house. The
obligation to pay can become reinstated again in case it turns out that breaking thewindow was not necessary for saving the child. Figure 7 shows the endpoint of thisexchange of reasons and counterreasons.
Obligation to
pay for thedamages

Break a window

Ground of justification

Save a child

Breaking window not necessary

Figure 7: Reinstatement
As a side issue, the example can be used to illustrate the need for 'attack warrants'.
In the example, it is debatable whether (in an actual legal system) the nonnecessity of the property right violation blocks the inference that saving the childgives rise to a ground of justification. It therefore can be relevant to specify theunderlying generic attack license (something like "When a property right violation is
not necessary, there is no ground of justification by force majeure"), and givebacking for that.
3.6

Argumentation schemes

Argumentation schemes can be regarded as a generalization of the rules ofinference of formal logic. The notion of argumentation schemes stems from the fieldof argumentation theory. Walton's (1996) treatment has been influential andprovides a useful overview with many examples. There also further references to9the argumentation theory literature can be found. Here are two informal versions oflogical rules of inferences:(1)

P. If P then Q.
Therefore Q.

(2)

All Ps are Qs. Some R is not a Q.
Therefore some R is not a P.

The former is an semi-formal version of Modus ponens, the latter is one of theclassically studied syllogisms. These two schemes fit in neat formal systems; theformer in many logical proof systems, but in particular in standard propositional
logic, the latter in the classification of syllogisms. Both are truth-preserving (in thesense that the truth of the schemes' conditions are taken to guarantee the truth oftheir conclusion) and allow no exceptions. Contrast these with the following two
schemes:(3)

Person E says that P. Person E is an expert with respect to facts like P.
Therefore P.

(4)

Doing act A contributes to goal G. Person P has goal G.
Therefore person P should do act A.

The former is a variant of argumentation from expert opinion, the latter a variant ofmeans-end reasoning. Although these schemes are recognizable as patterns thatcan occur in actual reasoning and are also - to some extent - reasonable, it isimmediately clear that the neatness and safeness of the schemes (1) and (2) does
not apply to (3) and (4). There is no clean formal system associated with (3) and(4), nor is one to be expected. They are not truth-preserving. For (3), it suffices tonote that an expert can be wrong and, for (4), it is even unclear how to establish
the truth of its conclusion. Furthermore, (3) and (4) allow exceptions. For instance,
an exception to scheme (3) occurs when an expert has a personal interest in sayingthat P. For scheme (4) it can be the case that there are other, better ways toachieve goal G, or it may be impossible to do A.
Argumentation schemes are context-dependent, defeasible and concrete
instead of universal, strict and abstract. To some, these properties may seem tomake argumentation schemes a useless tool of analysis, but it turns out that theproperties are in fact what makes argumentation schemes useful. At the sametime, argumentation schemes require a way of approaching the analysis ofreasoning different from one in terms of neat logical systems. And although a fullformalistic approach is not feasible given the nature of argumentation schemes, it is
not necessary to proceed without any systematicity. As argued by Verheij (2003b),
it is possible to approach argumentation schemes in a way that resembles thepractice of knowledge engineering, in which knowledge is extracted from domain
experts and represented in such a way that a machine can process it.
Argumentation schemes can be characterized using a format with four elements:
consequent, antecedent, exceptions and conditions of use.
Here is an example of the format for simple arguments based on expert
testimony:Consequent: P.
Antecedent: Person E says that P.
Person E is an expert with respect to facts like P.
Exception:
Person E is lying.

10

Condition:

Experts with respect to the facts like P provide reliable
information concerning the truth of P.

The format seems to abstract completely from the dialogue setting ofargumentation. For instance, the format does not have a slot for critical questions,although in the literature on argumentation schemes these play a central role. The
reason for this is that in our opinion the critical questions can be determined on thebasis of the format. In fact, the format suggests the following four kinds of criticalquestions:
1.

2.

3.
4.

Critical questions concerning the consequent of an argumentation scheme.
In the example: Are there other reasons, based on other argumentation
schemes for or against P?
Critical questions concerning the elements of the antecedent of anargumentation scheme.
In the example: Did person E say that P? Is person E an expert with respect
to facts like E?
Critical questions based on the exceptions of an argumentation scheme.
In the example: Is person E lying?
Critical questions based on the conditions of use of an argumentation
scheme.
In the example: Do experts with respect to the facts like P provide reliable
information concerning the truth of P?

This classification of critical questions shows that the proposed argumentation
scheme format can provide relevant insights for the dialogue setting ofargumentation. In a similar way, the format can be applied to the topic of burden of
proof. For instance, the proponent of a claim that P will have the burden to answer
questions by an opponent concerning the elements of the antecedent, whereas an
opponent will have to substantiate an exception. With respect to the consequent, it
is natural that a proponent of P has the burden of giving additional reasons for it,
whereas the opponent has the burden of giving reasons against it. Prakken andSartor (2008) and Gordon, Walton and Prakken (2007) provide further discussion of
burden of proof in relation with argumentation schemes.
For present purposes, the format is relevant because it provides a natural,
systematic approach to develop a set of argumentation schemes with respect to acertain topic. It consists of the following four-steps:
1.
2.
3.
4.

Determine the relevant types of sentences
Determine the conditional relations, i.e., the antecedents and consequentsof the argumentation schemes
Determine the exceptions, i.e, the arguments against the use of theargumentation schemes
Determine the conditions of use for the argumentation schemes

The four steps need not be followed in this order. It even often occurs that goesback to an earlier step and makes adaptations, until finally a set of argumentation
schemes is reached that serves one's purposes. This will be illustrated by theapplication of the method to the anchored narratives theory in the next section.
4

Argumentation schemes for the anchored narratives theory

In the following, the theory of anchored narratives (referred to as ANT from nowon) will be reconstructed in terms of argumentation schemes. As was said in the
introduction, Crombag, van Koppen and Wagenaar's theory met with some amount11

of criticism from evidence theorists. We suggested that this criticism could in partbe repaired by adding precision and detail to the use of terminology and by further
development of a number of key concepts in the theory. For example, Figure 1
which plays a central expository role in ANT, suggests that in ANT stories are only
anchored in general commonsense knowledge of the world, without a clear role forthe pieces of evidence themselves. During our research, we found that over theyears the original version of ANT has been subject to changes and interpretations,both by other researchers in the field as well as by its original authors. For ourreconstruction of ANT we have drawn from numerous written sources (Crombag etal. 1992, 1994, Wagenaar et al. 1993, De Poot et al. 2004, Wagenaar & Crombag2006) and from personal discussions with one of the original authors, Peter van
Koppen, in the context of the project 'Making sense of evidence' (Bex, Van den
Braak et al. 2007).
For expository reasons, the reconstruction will be performed step-by-step andcontains a number of retracings in the form of adaptations of results attained atearlier steps. For ease of reference, the final set of argumentation schemes that in
our view best expresses ANT has therefore been listed in the appendix.
4.1

Accepting the truth of a true story

The first step in the argumentation scheme method is to determine the relevant
types of sentences. In ANT, accepting a story as the true account of the facts
involves story quality and story anchoring. So here is a first shot at relevant
sentence types:
Story S is true.
Story S is good.
Story S is anchored.
The second step of the method is formulating argumentation schemes, i.e., theconditional relations that exist between the sentence types. For these sentences,
this is straightforward: the latter two taken together, when accepted as true, cangive support for accepting the truth of the former. Hence, an initial formulation of
ANT's central argumentation scheme is this:(1)

ANCHORED NARRATIVES: ACCEPTING A STORY AS TRUE
Consequent: Story S is true.
Antecedent: Story S is good.
Story S is anchored.

The scheme makes a fundamental distinction underlying ANT explicit: everythingthat has to do with the evidential support of a story is dealt with under the headingof anchoring, whereas story quality is related to the overall shape andcompleteness of the story. In ANT, story quality is a kind of pre-evidential
plausibility of a story. It is important and characteristic for ANT that story quality is
considered to be independent of the available evidence.
It should be noted that - although the scheme's consequent refers to thetruth of story S - the scheme is not intended to guarantee that its consequentobtains when its antecedent does. Clearly, it doesn't, for the truth of a story cannot
be ensured by its quality (goodness) and anchoring. This is in line with the natureof argumentation schemes, which point to defeasible reasons and make no claim totruth-preservation. The scheme purports to show how according to ANT the truth ofa story can be reasonably accepted as true. ANT is pragmatic in this respect, andtreats reasoning on the basis of evidence as a kind of pragmatic judgment, not as aguarantee of truth. In ANT, quality and anchoring provide a reason for accepting a

12story as being true. In addition, it is relevant to note that, in ANT, this scheme isthe only route to accepting the truth of a story.
How can the acceptance of the truth of a story be undermined in ANT? There
are three ways of doing that. First, one can argue that the story is not good, second
that it is not anchored, and third that there is an exception to the application of thescheme. Before we continue with the former two in our reconstruction of ANT's
treatment of story quality and anchoring (in the following two subsections), we turnto the possibility of exceptions to the application of the scheme (cf. step 3 of themethod). When there is an exception, the scheme's conclusion doesn't follow, eventhough the scheme's antecedent is fulfilled. So the question is: when a story isgood and anchored, which exceptional situations can - according to ANT - have theeffect that it is nevertheless unreasonable to accept the story's truth?
In ANT, one central exception to the scheme is recognized: the occurrenceof another story with equally good or better anchoring. This exception corresponds
to number 7 of the universal rules of evidence. Including this exception in thescheme leads to the following adaptation:(1')

ANCHORED NARRATIVES: ACCEPTING A STORY AS TRUE
Consequent: Story S about topic T is true.
Antecedent: Story S is good.
Story S is anchored.
Exception:
Story S' about topic T (unequal to S) has equally good or
better anchoring.

Looking at this formulation of the scheme leads to a suggestion for refinement: it
seems natural to assume that the requirement of goodness should hold both forstories taken to be true and for their competitors. In other words, the suggestion isthat alternative stories that are better or equally anchored, but that are notthemselves good, are not genuine competitors. Otherwise a rambling, ambiguousstory full of contradictions could preclude that an otherwise good and anchoredstory is taken to be true.
Incorporating this idea in the scheme, we get:
(1'')

ANCHORED NARRATIVES: ACCEPTING A STORY AS TRUE
Consequent: Story S about topic T is true.
Antecedent: Story S is good.
Story S is anchored.
Exception:
Story S' about topic T (unequal to S) is good, andStory S' (unequal to S) has equally good or better anchoring.

We discuss the adaptation (1'') here merely as a suggestion. We have modelledscheme 1'' in such a way that a story need not be better to push out a good story:
it suffices that story S' is good and has equally good anchoring. It is conceivablethat version (1') is closer to the original intention of Crombag, Van Koppen andWagenaar (but note the phrasing of universal rule of evidence no. 7). One reason
for preferring (1') could for instance be that even a bad, but better anchored story
might give sufficient doubt to reject an otherwise good story. Note however that
this may depend on the party that presents a story: stories by the prosecutor may
need a treatment different from those by the defendant. Here it is not a goal tosettle this issue. It is noteworthy however that the issue has naturally presented
itself as a side effect of the argumentation scheme method.

13

4.2

Story quality

Let us continue on the issue of story quality: how is story quality established in
ANT? A number of themes occur regularly in this respect. Following our method, we
express them in terms of sentence types:
Story S has a central action to which all elements are related.
Story S explains how the central action was performed.
Story S explains why the central action was performed.
Story S is unambiguous.
Story S contains the accused's motive.
Story S tells that the accused had the opportunity to commit the crime.
Story S does not contain contradictions.
In general, the central action of a prosecutor's story is the crime itself, though
there are examples discussed in ANT's main sources, in which the crime is not itself
the central action in the story that is the issue of the debate.7 Hence the accused's
motive (the fifth sentence type in the list above) is just one instance of a reason
why the central action was performed (the third sentence type). It therefore seems
reasonable that, in a generic scheme, the motive is left out. Similarly, opportunity(the sixth type) can be taken as an instance of the general constraint of internal
coherence of the story (the seventh type). A first version of an argumentation
scheme capturing these points is the following:(2)

ANCHORED NARRATIVES: STORY QUALITY
Consequent: Story S is good.
Antecedent: Story S has a central action to which all elements are related.
Story S explains how the central action was performed.
Story S explains why the central action was performed.
Story S is unambiguous.
Story S does not contain contradictions.

In section 4.4, we will have more to say about the scheme of story quality (which
will lead to refinements), but first we continue with the second central theme of
ANT, viz. story anchoring.
4.3

Story anchoring

It is especially in the part of story anchoring that ANT has occasionally led tomisunderstandings: why consider commonsense generalizations as anchors and not
the pieces of evidence themselves? Isn't providing good evidence the mostimportant way of justifying one's belief in the truth of a story? Certainly, andpresumably Crombag, Van Koppen and Wagenaar don't disagree, or at least notradically. Clearly they have not defended that believing a story is just a matter ofthe right ("safest") commonsense generalizations, while leaving aside the pieces ofevidence. Instead, what they have argued for, is that the value of a piece of
7

For instance, in the Haaknat case (discussed by Crombag et al. 1992, 1994 andWagenaar et al. 1993) the crime was a robbery, but the point at issue was why
Haaknat was found hiding for the police in a moat. Was Haaknat hiding because of
his involvement in a fight (as he himself claimed) or was it because of the robbery?
From the perspective of the crime, Haaknat's hiding is not a central action, but fromthe perspective of the decision making it was. In this way, if the identity of theperpetrator is at issue, the actual crime is always one of the possible stories that
explains some kind of (strange) behaviour by the suspect.

14evidence as proof for the occurrence of an event cannot be estimated independentof the commonsense generalization that connects the piece of evidence to theevent. For example, a story can only be reasonably believed on the basis of aconfession if confessions normally contain true stories. Moreover, ANT emphasizes
that the value of a piece of evidence is a function of the safeness of thecorresponding anchoring generalization. For instance, if the proof criterion is"beyond a reasonable doubt" (and not merely "reasonable"), the generalization "if
confessions normally contain true stories" does not seem to suffice. Thensomething stronger like "confessions almost always contain true stories" should betrue. One reason why ANT's authors elaborate at length on the importance ofanchoring generalizations is that their safe use can require consultation of experts,
for instance on the empirical findings about the safeness of witness testimony.
In a benevolent reading of ANT, there is no serious misconception withrespect to the relation between the justification of belief in a story, pieces ofevidence and the commonsense generalizations connecting them. ANT's use of themetaphor of anchors is not incoherent. Perhaps the specific version of the metaphor
is somewhat infelicitous, given the following observation: when discussing ANT, wehave repeatedly encountered that people tend to think of the pieces of evidence asanchors, and that it takes effort to instead think of the generalizations as anchors.
A slight change of the use of the metaphor seems in place: perhaps thegeneralizations should be thought of as the anchor chains. This adaptation of themetaphor does justice to the idea that the generalizations connect the piece ofevidence (in the metaphor: the anchor) to the story (the 'ship').
Let us continue with determining how the anchoring of a story can be dealt
with in our argumentation scheme reconstruction of ANT. A central type of sentencein anchoring is the following. It is phrased in such a way that it avoids the pitfalls of
the different interpretations of the anchors metaphor just described:(*)

Component C of story S is anchored to piece of evidence E by anchoring
generalization G.

Different phrasings of the same idea, less tied to ANT's preferred choice of words,
are of course possible, e.g.:(†)

Component C of story S finds support in piece of evidence E on the basis of
warranting generalization G.

Here the term "warranting" is related to Toulmin's (1958) warrants, viz. genericinference licenses (discussed in section 3). In certain circumstances, it can beworthwhile to split (†) into two parts, as follows:
Component C of story S finds support in piece of evidence E.
The support of component C of story S by piece of evidence E is warranted
by generalization G.
As we are reconstructing ANT, we will stay close to its terminology and use (*). It is
tempting to propose the following argumentation scheme:(3)

ANCHORED NARRATIVES: ANCHORING
Consequent: Story S is anchored.
Antecedent: There is a piece of evidence E.
Component C of story S is anchored to piece of evidence E byanchoring generalization G.
Anchoring generalization G is safe.

15

Indeed (3) expresses the core idea underlying ANT that anchoring a story involves
that some component of the story S is supported by a piece of evidence E, when asafe generalization connects E and C. However, the present scheme suggests thatfor a story's anchoring it suffices that one component is supported by evidence.
This is in general not correct: in a murder case it does not suffice to have evidence
for the victim being killed (although a murder case without a body is in trouble),while there is nothing to support who did the killing. On the other hand, it is also
not necessary (nor in general feasible) that all components of a story are directly
supported by evidence. For instance, sometimes even a murder case without abody can lead to a life sentence for the murderer (Court of Appeal Leeuwarden, July19, 2006; the victim had been burnt). ANT takes a middle way: not one, not all,but the essential components of a story must be supported by evidence (universal
rule of evidence no. 3).
One way of capturing these ideas in an argumentation scheme is in terms of
the specification of a reason against a story's anchoring: a story is not wellanchored when there is an essential component that is not safely anchored.8 A
story component is safely anchored when it is anchored to a piece of evidence anda corresponding safe generalization. Scheme 3 is split into two:
(3a)

ANCHORED NARRATIVES: ATTACKING THE ANCHORING OF A STORY
Consequent: Story S is not well-anchored.
Antecedent: Component C of story S is essential.
Component C of story S is not safely anchored.

(3b)

ANCHORED NARRATIVES: COMPONENT ANCHORING
Consequent: Component C of story S is safely anchored.
Antecedent: There is a piece of evidence E.
Component C of story S is anchored to piece of evidence E byanchoring generalization G.
Anchoring generalization G is safe.

Four differences with the original scheme (3) are worth mentioning. First thescheme's direction of support has flipped: instead of a scheme that expresses how
to support a story's anchoring, it is now replaced by scheme (3a) expressing how to
attack a story's anchoring. Second it now is made explicit that a subset of story
elements needs support by evidence, namely the essential components. Third the
choice of words in the consequent is now more normatively loaded: instead ofsimply speaking of anchoring, we now speak of well-anchoring. In this way, it isclearer that story anchoring is a matter of degree and of judgment. This also leads
to a slight adaptation of scheme (1''). The requirement for accepting a story as true
now becomes that a story is well-anchored, instead of merely being anchored:(1''')ANCHORED NARRATIVES: ACCEPTING A STORY AS TRUE
Consequent: Story S about topic T is true.
Antecedent: Story S is good.
Story S is well-anchored.
Exception:
Story S' about topic T (unequal to S) is good, andStory S' (unequal to S) has equally good or better anchoring.

Fourth, we have now two kinds of anchoring: the anchoring of stories (scheme(3a)) and the anchoring of story components (scheme (3b)).

8

Another way is the use of a universal quantifier: supporting a story's wellanchoring requires that all essential components are safely anchored.

16

There is no general method for determining the safeness of anchoring
generalizations. It is for instance always possible to argue that the case underconsideration is an exception. ANT gives some advice, though. Specificity isrelevant for determining safeness in the sense that it is easier to decide about arule's correctness when it is more specific, but specificity cannot warrant
correctness (Wagenaar et al. 1993, p. 40). ANT has one general attack against thesafety of anchoring generalizations, viz. their obvious falsity (cf. universal rule ofevidence no. 7):(4)

ANCHORED NARRATIVES: OBVIOUSLY FALSE GENERALIZATIONS
Consequent: Anchoring generalization G is not safe.
Antecedent: Anchoring generalization G is obviously false.

Scheme (3a) is the attack of a story being well-anchored that is most characteristic
for ANT: only stories of which the essential components are safely anchored are
well-anchored. Besides this attack, ANT has two other attacks of a story being wellanchored. One is based on the interdependence of anchoring (scheme (5) below
based on universal rule of evidence no. 4), the other on the falsification of a story(scheme (6) below based on universal rule of evidence no. 8):(5)

ANCHORED NARRATIVES: ATTACK BY INTERDEPENDENCE OF ANCHORING
Consequent: Story S is not well-anchored.
Antecedent: The anchoring of (unequal) components C
interdependent.
Component C of story S is essential.
Component C' of story S is essential.

and

C'

is

Interdependent anchoring for instance occurs when the case against a suspect(including identity, actus reus and mens rea) is based only on his confession or only
on the testimony by the victim.
(6)

ANCHORED NARRATIVES: ATTACK BY FALSIFICATION
Consequent: Story S is not well-anchored.
Antecedent: Story S is falsified.

There does not seem to be an explicit description of what story falsification
amounts to in ANT. The following scheme suggests one approach:(7)

ANCHORED NARRATIVES: FALSIFICATION
Consequent: Story S is falsified.
Antecedent: Component C of story S is essential.
The opposite of component C of story S is anchored to pieceof evidence E by anchoring generalization G.
Anchoring generalization G is safe.

It may be worthwhile to emphasize one difference between the antecedents of (7)and (3a): whereas (3a)'s antecedent involves an essential component that is notsafely anchored, in (7)'s antecedent the opposite of an essential component issafely anchored.
4.4

Recursiveness of stories in reasoning about evidence

We now turn to an issue related to ANT that we did not learn directly by reading its
main sources, but by conversations with one of its authors: Peter van Koppen. The
conversations took place in the context of the already mentioned project 'Making

17

sense of evidence'. Van Koppen emphasized again and again that not only the factsof a crime are stories, but also the pieces of evidence that support or attack thetruth of a story themselves.9 For us, Van Koppen's position was rather surprising as
we tended to think of pieces of evidence as giving rise to the reasons that support
or attack crime stories. So in our minds there was a dichotomy between reasonsand stories, a dichotomy that did not seem to exist (or at least not in the sameway) in Van Koppen's conceptualisation.
The point is related to the issue of real evidence, in Wigmore's terminology:'autoptic proference'. With real evidence, no inference is required; the thing itself is
its proof. For example, to prove that there is a knife by means of autoptic
proference, one only has to show the knife itself. There is however a problem with
the idea that the thing proves itself: it only proves itself. Peter Tillers wrote aninteresting piece about this in his web log.10 Showing a knife and saying 'there is aknife' may prove that there is a knife, but it could just as well be the knife thejudge used to cut his steak with the day before. What has to be proved, that the
knife was used in a brutal murder, cannot be proved by just the knife itself. We
need forensic expertise on fingerprints, police reports about where the knife wasfound and so on. In other words, it has to be shown why and how the knife is partof the evidence for the event that a person was brutally murdered with the knife.
Van Koppen's position can be regarded as an answer to this problem of real
evidence. On one occasion, he argued that finding a hair on the crime scene thatmatches the accused's DNA does not mean that the accused committed the crime;a good and properly anchored story has to be constructed that tells us that the hair
was in fact left on the scene of the crime at the moment that the accusedcommitted the crime.
However, Van Koppen's position that a piece of evidence is a story provides
a theoretical complication: are pieces of evidence not first and foremost (sourcesfor) reasons that support or attack crime stories? What happens to this idea whenpieces of evidence are to be regarded as stories? Are then piece-of-evidence stories
supportive for facts-of-the-crime stories? Are piece-of-evidence stories of "thesame kind" as facts-of-the-crime stories? Are they to be evaluated in the same
way? And so on.
In this section, an approach to the resolution of this theoretical complication
is proposed. The provided solution leads to the main clarification (perhaps:
adaptation) of ANT resulting from our reconstruction, while retaining ANT's spirit.11
The approach is based on recursiveness. In argumentation, one version ofrecursiveness meets the eye immediately. It is the recursiveness of reasons. To
defend (or attack) a claim, one gives reasons, but for these reasons on their turnreasons can be given, and so on. Recursiveness of reasons occurs in any kind ofargumentation, hence also in the context of evidential argumentation (see, e.g.,Anderson et al. 2005 and our own previous work Bex, Van den Braak et al. 2007).
However, in our reconstruction of ANT another kind of recursiveness is used,
one that fits Van Koppen's position that pieces of evidence are stories. This
recursiveness is the recursiveness of stories in reasoning about evidence:12 to
9This theoretical position nicely fits Van Koppen's conversation style: he is a gifted
teller of stories.
10
'The
Chain
Saw
Did
Not
Speak
Clearly',
June
09,
2005,
tillerstillers.blogspot.com/2005/06/chain-saw-did-not-speak-clearly.html.
Page
accessed on March 31, 2008.
11
It is our hunch that the authors of ANT will not consider what will follow to be agenuine adaptation, but at best a clarification. If so, the reconstruction has
succeeded.
12This kind of recursiveness of stories is different from the recursiveness of story
schemes mentioned by (Bex 2008). There, the events of a sub-story are essentially18

establish the truth of a facts-of-the crime story, its essential components must be
safely anchored (to a piece of evidence by an anchoring generalization; cf. scheme(3') above). But for this component anchoring, a story about a piece of evidence
must be provided, and this story must be accepted as true. The recursion arises
since accepting the truth of a piece-of-evidence story is analogous to accepting thetruth of a facts-of-the-crime story: like a facts-of-the-crime story, a piece-ofevidence story is accepted as true when it is good and well-anchored, and there isno competing story (cf. scheme (1''')). The recursion can continue, since arguingfor the truth of a piece-of-evidence story can involve further piece-of-evidence
stories, and so on.
If we apply this idea of the recursiveness of stories in our reconstruction of
ANT, scheme (3b) about component anchoring only needs a slight adaptation:(3b')

ANCHORED NARRATIVES: COMPONENT ANCHORING
Consequent: Component C of story S is safely anchored.
Antecedent: There is a piece of evidence E.
Story SE about piece of evidence E is true.
Component C of story S is anchored to piece of evidence E byanchoring generalization G.
Anchoring generalization G is safe.

We simply added a conjunct to the scheme's antecedent, viz. 'Story SE about pieceof evidence E is true'. Note that the scheme now refers to two stories: a story S
and a story SE about a piece of evidence used to support a component of story S.
The story S can be about the facts of a crime, or, recursively, about a piece ofevidence. The effect of this adaptation is that the truth of stories about pieces ofevidence is now treated on a par with other stories, viz. by story quality and bystory anchoring.
As an illustration, we return to the example of a hair found on the scene of
the crime, and use it to establish whether the accused was at the scene of thecrime. Initially, there is a very simple story about the hair, so simple that the term'story' is somewhat unbefitting:A hair is found on the scene of the crime and the hair's DNA matches that of
the accused.
If this story would be used to defend that the accused was at the scene of thecrime, the following anchoring generalization is needed:
If a hair is found on the scene of the crime and the hair's DNA matches thatof the accused, then the accused was at the scene of the crime.
The defence could for instance argue that this generalization is not sufficiently safe
to conclude (using (3b')) that the story component 'The accused was at the sceneof the crime' is safely anchored.
Let's next consider the more complicated situation of the frustrated
investigator. Here is the story:
A hair is found on the scene of the crime and the hair's DNA matches that of
the accused. The hair was planted on the scene of the crime by a frustrated
investigator.

a subset of the main story, while here one story (typically about a piece ofevidence) plays a role in accepting another (typically about the facts of the crime).

19

If we were to use this story for anchoring, we would need the following anchoring
generalization:
If a hair is found on the scene of the crime and the hair's DNA matches thatof the accused and it is planted there, then the accused was at the scene of
the crime.
This generalization is obviously false, and scheme (4) could be used to attack its
use for safe anchoring. As a result, applying scheme (3b') to the planted hair does
not lead to the safe anchoring of the story component that the accused was at thescene of the crime.
One may wonder whether (3b') isn't an unnecessarily involved version of(3b). Why treat pieces of evidence as stories in the first place? Can't they betreated as elementary propositions (as is in a way the case in (3b))? The answer is:that depends on the circumstances, but in this respect the situation for the facts ofthe crime is analogous to that of pieces of evidence. For simple stories, either about
the facts of the crime or about pieces of evidence, a story approach as in ANT, inwhich story quality and story anchoring are established, is indeed often overly
involved. Then an approach with propositions and reasons (e.g., styled as in section3) suffices. As soon as a story gets more complex, or establishing its truth becomes
more involved, a story approach as in ANT can come in useful. This can for instanceoccur when there are several good, hence plausible, but competing stories, or when
discussion is possible about the plausibility of a story or about one of thegeneralizations used. A defence of a story-based approach against (or incomparison with) a reason-based approach is however beyond the goals of thepresent paper (see, e.g., Twining's (1999) reflections that are very relevant in thisrespect).
4.5

Other story structures

Looking back at the schemes proposed, after having introduced the recursivenessof stories, it turns out that with hindsight one scheme requires adaptation, namely
scheme (2). In fact, the specifics of scheme (2) may be a reason why therecursiveness of stories underlying ANT was not so readily clear: scheme (2) isabout stories that involve an intentional crime, and stories about pieces of evidence
are not in general about intentional crime. It is noteworthy that scheme (2) isalready somewhat more general than the main descriptions of ANT since scheme(2) is in fact a scheme about intentional action in general, and not just about
intentional crime.
Our example illustrates the problem: the simple story about the hair does
not contain an intentional action, whereas the extended story does. Although themore complex story involves intentional action, this is not in general the case formore complex piece-of-evidence stories. For instance, there is no intentional actionin the situation that the accused's hair was accidentally dragged to the scene of thecrime (e.g., the accused, living in the same street as the scene of the crime, haslost a hair on the street, which subsequently got stuck to the victim's shoe, etc.). In
sum, there are other stories than those about intentional action, of which it can berelevant to establish truth in terms of story quality (hence plausibility) andanchoring.
The reason why intentional action was so explicitly built into scheme (2) isthat intentional action is so explicitly built into ANT. In ANT, story quality isconnected to story structures (also called story grammars), and these in turn areconnected to intentional action, at least in the main sources of inspiration for ANT(Bennett & Feldman and Pennington & Hastie). For stories about the facts ofintentional crime, this is a wholly natural approach. For other stories that are20

relevant in reasoning about evidence, such as stories about unintentional crime(e.g., criminally negligent homicide) or about pieces of evidence, this is not soclear.
What is needed is a way to incorporate other story structures than one forintentional action or crime in ANT's main approach. Here is a proposal to adapt
scheme (2) to allow different story structures:(2')

ANCHORED NARRATIVES: STORY QUALITY
Consequent: Story S is good.
Antecedent: Story S fits story structure G .
Story S is unambiguous.
Story S does not contain contradictions.

In this scheme, we have deleted all references to intentional crime. Instead, theexistence of a fitting story structure (such as one for intentional crime) has been
given an explicit place. We have done this as it seems reasonable that different
kinds of stories have different story structures. For instance, it is to be expectedthat a murder story has a story structure different from a story about a hair on thescene of the crime. One could say that different story structures represent "factual
types". For instance, a murder story S belongs to the factual type of murders. A
hair on the scene of the crime belongs to the factual type of forensic evidence, or
perhaps even of hairs on the scene of the crime.
We will not develop a theory of factual types and their story structures here.
We will suggest, however, how the story structure for intentional action (the oneused in ANT) can be integrated into our argumentation scheme reconstruction. A
further scheme is needed that specifies the elements of a story type:(8)

ANCHORED NARRATIVES: FITTING THE STORY STRUCTURE OF INTENTIONAL CRIME
Consequent: Story S fits story structure G.
Antecedent: Story structure G requires a central action to which allelements are related.
Story structure G requires an explanation of how the central
action was performed.
Story structure G requires an explanation of why the central
action was performed.
Story S has a central action to which all elements are related.
Story S explains how the central action was performed.
Story S explains why the central action was performed.

Bex (2008) describes further work on fitting story structures.
5

Concluding remarks

The present reconstruction of ANT relates to our previous work on reasoning withevidence (Bex, Prakken et al. 2007, Bex, Van den Braak et al. 2007), as follows. In
the previous work, stories are modelled as causal networks that explain the central
event. Pieces of evidence are connected to the events in the story using defeasible
arguments, thus creating a formal framework for an argumentative story-based
analysis of evidence. Several features of ANT also occur in this formal framework.
Component anchoring and attacking a story's anchoring, here schemes (3a), (3b')
and (4), are modelled using defeasible arguments, where an event or component ofa story is anchored if it follows from an undefeated argument based on a piece ofevidence. Story falsification, schemes (6) and (7), is also modelled, as the opposite
of a story component can be the conclusion of an argument based on a piece ofevidence. Furthermore, the causal networks that model stories are not allowed to21

contain contradictions and implausible or unambiguous causal links can be defeatedby arguments, thus ensuring that a story does not contain contradictions and that it
is unambiguous (scheme (2')). Stories can be compared by looking at how many
components of a story are anchored in evidence (cf. the exception of scheme (1''')).
Anderson et al. (2005) also discuss stories in the context of reasoning withevidence. They give a protocol for analysing the plausibility, coherence andevidential support of stories. This protocol consists of a list of questions. Somepoint to the evidential support for the story, for example, 'To what extent does theevidence support the story?' and 'Is there evidence that conflicts with the story?'
Other questions are meant for analysing the plausibility of the story, for example,'Is the story supported by plausible background generalizations?' and 'Does thestory fit a familiar story such as Cinderella and what is the relevance of this?'In this text we have developed a reconstruction of the theory of anchorednarratives (ANT) in terms of argumentation schemes. The schemes are listed in the
appendix. Our contribution can be summarized as follows.
-

-

-

-

-

ANT's central metaphor of stories anchored by generalisations that connect
pieces of evidence with story components can be confusing, especially since
many intuitively think of the pieces of evidence as anchors, and not thegeneralisations. Still ANT's message that justifying one's belief in a story is afunction of the safeness of the generalizations used is sound. Our
reconstruction has shown one way to bypass the confusion.
Our reconstruction in terms of argumentation schemes shows how ANT's
story-based approach can be treated in a context of argumentation, while
retaining the emphasis on stories as wholes. It provides an integration ofargumentation and stories different from the one by Bex et al (2007). There
we discussed the use of stories in terms of causal networks and abductive
reasoning. The emphasis was on formalized defeasible arguments about
elements of stories. In contrast, here the focus is on semi-formal
argumentation schemes in which the role of stories (as wholes) is madeexplicit.
On the basis of the reconstruction we proposed some refinements andclarifications of ANT. A minor one is incorporated in scheme (1'''). We
suggested that only good, i.e., plausible, stories with equal or betteranchoring can exclude one's acceptance of a story.
A further clarification is more fundamental: it is the recursive use of stories.
Not only the acceptance of stories about the facts of the crime, but also
about other factual situations, such as those about a piece of evidence, canbe treated in ANT. The clarification is incorporated in scheme (3b'), in which
the safe anchoring of a story component requires a story about a supporting
piece of evidence. In section 4.4, it is explained that such extended,recursive use of stories is natural, but may be too complex for simple cases.
The recursive use of stories led to a further relevant refinement, namely theneed for other story structures than only a story structure for intentional
crime. When stories cannot only be about the facts of a case of intentional
crime, but also about the facts of unintentional crime and pieces ofevidence, then different story structures are needed in order to establish
their plausibility, or, in ANT's preferred terminology: quality. This refinementis specified in scheme (2').

In sum, we conclude that an argumentation schemes reconstruction of the theoryof anchored narratives is possible, and that the exercise leads to a number of
relevant clarifications and refinements.
The result helps to clarify the criticisms against ANT mentioned in the
introduction: The notions of stories and arguments have been given a clear and22

separate role when considering the truth of a story about the facts. There is adefinite distinction between reasons based on pieces of evidence and stories about
pieces of evidence. The relation between common-sense generalisations and piecesof evidence and the way in which they help (and don't help) accepting or rejecting
facts and stories as true has been clarified. ANT's universal rules of evidence haveshown their usefulness for developing the set of argumentation schemes. A place
has been found for on the one hand commonsense generic beliefs (viz. ANT's
anchoring generalisations) and on the other commonsense knowledge of scenarios(viz. story structures for different factual types).
As theoretical contribution, we have provided an account of reasoning about
the facts in which not only the elements of stories are part of argumentation, butalso stories as wholes. We have argued that accepting the truth of a story candepend on accepting the truth of other stories (cf. the recursiveness of stories;
section 4.4) and that story structures different from one for intentional crime areneeded (section 4.5).
We conclude that the explicit nature of the set of argumentation schemes(cf. the list in the appendix) can be the basis for further discussion about the theoryof anchored narratives in relation to other approaches towards reasoning about thefacts of criminal cases, and for the future development of our knowledge about how
such reasoning can and should be done as well as possible. The topic deserves ourongoing attention, since the task of the rational choosing of truth, facing our courts,
is both necessary and dangerous.13
Appendix: the set of argumentation schemes(1''')ANCHORED NARRATIVES: ACCEPTING A STORY AS TRUE
Consequent: Story S about topic T is true.
Antecedent: Story S is good.
Story S is well-anchored.
Exception:
Story S' about topic T (unequal to S) is good.
Story S' (unequal to S) has equally good or better anchoring.

(2')

ANCHORED NARRATIVES: STORY QUALITY
Consequent: Story S is good.
Antecedent: Story S fits story structure G .
Story S is unambiguous.
Story S does not contain contradictions.

(3a)

ANCHORED NARRATIVES: ATTACKING THE ANCHORING OF A STORY
Consequent: Story S is not well-anchored.
Antecedent: Component C of story S is essential.
Component C of story S is not safely anchored.

(3b')

ANCHORED NARRATIVES: COMPONENT ANCHORING
Consequent: Component C of story S is safely anchored.
Antecedent: There is a piece of evidence E.
Story SE about piece of evidence E is true.
Component C of story S is anchored to piece of evidence E byanchoring generalization G.
Anchoring generalization G is safe.

(4)

ANCHORED NARRATIVES: OBVIOUSLY FALSE GENERALIZATIONS
Consequent: Anchoring generalization G is not safe.

13

Cf. Twining (1999).

23

Antecedent:(5)

Anchoring generalization G is obviously false.

ANCHORED NARRATIVES: ATTACK BY INTERDEPENDENCE OF ANCHORING
Consequent: Story S is not well-anchored.
Antecedent: The anchoring of (unequal) components C
interdependent.
Component C of story S is essential.
Component C' of story S is essential.

and

C'

is

(6)

ANCHORED NARRATIVES: ATTACK BY FALSIFICATION
Consequent: Story S is not well-anchored.
Antecedent: Story S is falsified.

(7)

ANCHORED NARRATIVES: FALSIFICATION
Consequent: Story S is falsified.
Antecedent: Component C of story S is essential.
The opposite of component C of story S is anchored to pieceof evidence E by anchoring generalization G.
Anchoring generalization G is safe.

(8)

ANCHORED NARRATIVES: FITTING THE STORY STRUCTURE OF INTENTIONAL CRIME
Consequent: Story S fits story structure G.
Antecedent: Story structure G requires a central action to which allelements are related.
Story structure G requires an explanation of how the central
action was performed.
Story structure G requires an explanation of why the central
action was performed.
Story S has a central action to which all elements are related.
Story S explains how the central action was performed.
Story S explains why the central action was performed.

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