Christian Dahlman

Christian Dahlman
Lund University | LU · Department of Jurisprudence

PhD

About

31
Publications
7,222
Reads
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116
Citations
Citations since 2017
18 Research Items
102 Citations
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20172018201920202021202220230510152025
Introduction

Publications

Publications (31)
Article
Full-text available
In this paper we compare causal models with reason models in the construction of Bayesian networks for legal evidence. In causal models, arrows in the network are drawn from causes to effects. In a reason model, the arrows are instead drawn towards the evidence, from factum probandum to factum probans. We explore the differences between causal mode...
Book
Philosophical Foundations of Evidence Law presents a cross-disciplinary overview of the core issues in the theory and methodology of adjudicative evidence and factfinding, assembling the major philosophical and interdisciplinary insights that define evidence theory, as related to law, in a single book. The volume presents contemporary debates on tr...
Chapter
This chapter maps out the scope of the epistemic authority of expert witnesses as interpreters and explainers of evidence and uncertainties that fall within their expertise. They argue that experts should only testify about questions of fact and ought not to express their opinions on questions of law and other ultimate adjudicative issues such as t...
Article
Full-text available
Judges should not be influenced by legally irrelevant circumstances in their legal decision making and judges generally believe that they manage legally irrelevant circumstances well. The purpose of this experimental study was to investigate whether this self-image is correct. Swedish judges (N = 256) read a vignette depicting a case of libel, wher...
Article
The problem of ‘naked statistical evidence’ is one of the most debated issues in evidence theory. Most evidence scholars agree that it is deeply problematic to base a verdict on naked statistical evidence, but they disagree on why it is problematic, and point to different characteristics of naked statistical evidence as the root of the problem. In...
Article
The authors investigate to what extent an evaluation of legal evidence in terms of coherence (suggested by Thagard, Amaya, Van Koppen and others) is reconcilable with a probabilistic (Bayesian) approach to legal evidence. The article is written by one author (Dahlman) with a background in the bayesian approach to legal evidence, and one author (Mac...
Article
Full-text available
When interpreting a natural language argument that generalizes over a contextually relevant category, audiences are likely to activate the category prototype and transfer its characteristics onto category instances. A generalized argument can thus appear more (respectively less) persuasive than one mentioning a specific category instance, provided...
Article
Research suggests that jurors misunderstand the presumption of innocence. However, past studies have not asked participants to estimate the defendant’s probability of guilt, setting aside the fact of charge and indictment. We conduct two studies to explore the impact of this question wording on estimates of the probability of guilt/innocence by jur...
Article
Full-text available
One of the greatest challenges to the use of probabilistic reasoning in the assessment of criminal evidence is the ‘problem of the prior’, i.e. the difficulty in establishing an acceptable prior probability of guilt. Even strong supporters of a Bayesian approach have often preferred to ignore priors and focus on the likelihood ratio (LR) of the evi...
Article
This article shows how Bayesian thinking can help legal fact‐finders to avoid some common fallacies and biases in the evaluation of legal evidence (false dichotomy, dependence neglect, and miss rate neglect).
Article
Full-text available
A Bayesian assessment of the probability that the defendant in a criminal trial is guilty depends on the presumed base rate for guilt and the estimated likelihoods of the evidence. This article explores how the base rate shall be determined. Bayesian scholars have recommended a base rate of 1/N, where N is the number of 'possible perpetrators', but...
Article
Full-text available
Although legal contexts are subject to biased reasoning and decision making, to identify and test debiasing techniques has largely remained an open task. We report on experimentally deploying the technique “giving reasons pro et contra” with professional (N = 239) and lay judges (N = 372) at Swedish municipal courts. Using a mock legal scenario, pa...
Conference Paper
Full-text available
One of the greatest impediments to the use of probabilistic reasoning in legal arguments is the difficulty in agreeing on an appropriate prior probability for the ultimate hypothesis, (in criminal cases this is normally "Defendant is guilty of the crime for which he/she is accused"). Even strong supporters of a Bayesian approach prefer to ignore pr...
Article
Full-text available
Arguments on legal evidence rely on generalizations, that link a certain circumstance to a certain hypothesis and warrants the claim that the circumstance makes the hypothesis more probable. Some generalizations are acceptable and others are unacceptable. A generalization can be unacceptable on at least four different grounds. A false generalizatio...
Article
Research on probabilistic reasoning has discovered several systematic errors, among which base rate neglect and the fallacy of the transposed conditional have featured prominently. This article introduces the term miss rate neglect to capture the systematic failure to properly account for false positives, i.e. the probability of evidence (E) given...
Article
This article is concerned with criminal trials where the defendant is a convicted felon with a prior conviction for the same offence. The article investigates a probabilistic argument that I will call the felony argument . According to the felony argument, the fact that the defendant has been previously convicted for the same offence has probative...
Article
Full-text available
An argument that makes use of a generalization activates the prototype for the category used in the generalization. We conducted two experiments that investigated how the activation of the prototype affects the persuasiveness of the argument. The results of the experiments suggest that the features of the prototype overshadow and partly overwrite t...
Article
Full-text available
The standard of proof in criminal trials should require that the evidence presented by the prosecution is robust. This requirement of robustness says that it must be unlikely that additional information would change the probability that the defendant is guilty. Robustness is difficult for a judge to estimate, as it requires the judge to assess the...
Chapter
In this chapter, we offer a Bayesian model for evaluating expert testimony in the court room. Statements from a putative expert are difficult for a legal decision maker to assess, as the legal decision maker – who lacks expert knowledge on the subject issue – must distinguish between experts that are highly reliable and experts that are less reliab...
Book
This book provides theoretical tools for evaluating the soundness of arguments in the context of legal argumentation. It deals with a number of general argument types and their particular use in legal argumentation. It provides detailed analyses of argument from authority, argument ad hominem, argument from ignorance, slippery slope argument and ot...
Chapter
Arguments ad hominem are common in political debates, legal argumentation and everyday conversations. In this article, we propose a general definition of ad hominem arguments. An argument ad hominem is an argument that makes a claim about the reliability of a person in the performance of a certain function, based on some attribute relating to the p...
Book
This book offers its readers an overview of recent developments in the theory of legal argumentation written by representatives from various disciplines, including argumentation theory, philosophy of law, logic and artificial intelligence. It presents an overview of contributions representative of different academic and legal cultures, and differen...
Article
Full-text available
This article claims that the requirement of Opinio Juris in the formation of customary international law means that a general practice must be generally accepted among states to become customary law. The article argues that Opinio Juris serves an important function. It prevents generally unwanted general practice from becoming customary law.
Article
Legal positivism used to be a lean theory. When it first entered the arena,challenging natural law theory, it was strikingly lean compared to itsopponent. It offered a thin concept of law, to replace the thick, value-ladenconcept developed in the natural law theory. And this was its strength. Thechampions of legal positivism argued convincingly that...
Article
The analysis of legal statements that are made from an “internal point of view” must distinguish statements where legal obedience is accepted from statements where legal obedience is only assumed. Statements that are based on accepted obedience supply reasons for action, but statements where obedience is merely assumed can never provide reasons for...
Article
According to Svein Eng there are propositions concerning the law which are descriptive as well as normative, but cannot be separated into one descriptive and one normative proposition. Eng calls these propositions "fused" ("sammensmeltede"). In Eng's theory a proposition with "fused modality" is partly descriptive and partly normative, but cannot b...

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Projects

Projects (2)
Project
The project aims to improve evidence-based decision-making in areas such as medicine, law, forensics, and transport. What makes it radical is that it plans to do this in situations (common for critical risk assessment problems) where there is little or even no data, and hence where traditional statistics cannot be used. Our solution is to develop a method to systemize the way expert driven causal (Bayesian Network) models can be built and used effectively either in the absence of data or as a means of determining what future data is really required. Working with relevant domain experts, along with cognitive psychologists, our methods will be developed and tested experimentally on real-world critical decision-problems. The proposed research has the potential to both reduce at source much unnecessary data collection and improve the results of analysis of data that is collected. It has the potential to provide rigorous, rational, auditable, visible and quantified probabilistic arguments to support decision-making and recommendations in areas where currently only ‘gut-feel’ is possible. This could lead to: more rational and defensible strategic policy making by decision makers in government, financial, and other organisations; better medical diagnostics; better understanding of the impact of different types of legal and forensic evidence. The project will enable scientists, statisticians, medics and lawyers, to be better able to reason about probability and understand the role and limitations of data, making better decisions with less data. http://bayes-knowledge.com/