Tribunals have come to depend increasingly on expertise for determining the facts in cases. However, current legal methods have proved problematic to work with. This paper argues that, as a special model of public understanding of science, assessing expertise should consider source credibility of expertise from internal aspects, including scientific validity and reliability, and external aspects involving the credibility of experts. Using the Carneades Argumentation System we show that the internal and the external aspects are mediated by the structure of (...) the argument from expert opinion with its matching set of critical questions. (shrink)

In this paper, it is argued that the most fruitful approach to developing normative models of argument quality is one that combines the argumentation scheme approach with Bayesian argumentation. Three sample argumentation schemes from the literature are discussed: the argument from sign, the argument from expert opinion, and the appeal to popular opinion. Limitations of the scheme-based treatment of these argument forms are identified and it is shown how a Bayesian perspective may help to overcome these. At the same time, (...) the contributions of the standard scheme-based approach are highlighted, and it is argued that only a combination of the insights of different traditions will yield a complete normative theory of argument quality. (shrink)

This paper combines three computational argumentation systems to model the sequence of argumentation in a famous murder trial and the appeal procedure that followed. The paper shows how the argumentation scheme for argument from expert opinion can be built into a testing procedure whereby an argument graph is used to interpret, analyze and evaluate evidence-based natural language argumentation of the kind found in a trial. It is shown how a computational argumentation system can do this by combining argument schemes with (...) argumentation graphs. Frighteningly, it is also shown by this example that when there are potentially confusing conflicting arguments from expert opinion, a jury can only too easily accept a conclusion prematurely before considering critical questions that need to be asked. (shrink)

The appeal to expert opinion is an argument form that uses the verdict of an expert to support a position or hypothesis. A previous scheme-based treatment of the argument form is formalized within a Bayesian network that is able to capture the critical aspects of the argument form, including the central considerations of the expert's expertise and trustworthiness. We propose this as an appropriate normative framework for the argument form, enabling the development and testing of quantitative predictions as to how (...) people evaluate this argument, suggesting that such an approach might be beneficial to argumentation research generally. We subsequently present two experiments as an example of the potential for future research in this vein, demonstrating that participants' quantitative ratings of the convincingness of a proposition that has been supported with an appeal to expert opinion were broadly consistent with the predictions of the Bayesian model. (shrink)

In place of the traditional epistemological view of knowledge as justified true belief we argue that artificial intelligence and law needs an evidence-based epistemology according to which scientific knowledge is based on critical analysis of evidence using argumentation. This new epistemology of scientific evidence (ESE) models scientific knowledge as achieved through a process of marshaling evidence in a scientific inquiry that results in a convergence of scientific theories and research results. We show how a dialogue interface of argument from expert (...) opinion, along with its set of critical questions, provides the argumentation component of the ESE. It enables internal scientific knowledge to be translated over into a wider arena in which individual nonexpert citizens and groups can make use of it. The external component shows how evidence is presented and used in a legal procedural setting that includes fact-finding, weighing the credibility of expert witnesses, and critical questioning of arguments. The paper critically reviews the standards of admissibility of scientific evidence using the ESE. (shrink)

ABSTRACTIn order to properly understand how expert disagreement should be dealt with, it is essential to grasp how expert opinion is used in the reasoning process by which humans reach conclusions and make decisions. This paper utilises the tools of argumentation theory, specifically Douglas Walton’s argument schemes, and variations upon them, in order to examine how patterns of reasoning are affected by the presence of conflicting testimony. This study suggests that although it may be supplemented with the construction of epistemic (...) hierarchies, the scheme of reasoning for the appeal to expert opinion provides no mechanism for establishing a preference for one expert statement over another, making it impossible to reach any rational conclusion as to the likely truth of the matter. Further, it is also argued that other schemes for presumptive argumentation are either unhelpful in themselves or lead to unwanted consequences. (shrink)

While courts depend on expert opinions in reaching sound judgments, the role of the expert witness in legal proceedings is associated with a litany of problems. Perhaps most prevalent is the question of under what circumstances should testimony be admitted as expert opinion. We review the changing policies adopted by American courts in an attempt to ensure the reliability and usefulness of the scientific and technical information admitted as evidence. We argue that these admissibility criteria are best seen in a (...) dialectical context as a set of critical questions of the kind commonly used in models of argumentation. (shrink)

A Bibliography of Douglas Walton’s Published Works, 1971-20.

I discuss under what conditions the objection that an expert’s argument is biased by her self-interest can be a meaningful and sound argumentative move. I suggest replacing the idea of bias qua self-interest by that of a conflict of interests, exploit the distinction between an expert context and a public context, and hold that the objection can be meaningful. Yet, the evaluation is overall negative, because the motivational role of self-interest for human behavior remains unclear. Moreover, if recent social-psychological results (...) from the “heuristics and biases” program are accepted, it is plausible to assume that humans also satisfice (rather than optimize/maximize) when identifying and then acting in their self-interest. My thesis is: insofar as the objection is sound with a particular audience, it is not needed; and insofar as the objection is needed, it is unsound. (shrink)