Abstract

Cognitive biases (or logical fallacies) are unconscious distortions of the way of thinking and are present in every human reasoning, including the juridical one. Despite cognitive biases are well known and well described in the literature, their impact on juridical decision-making is still unknown. In this article, we will rely on the well-known Human Expert Performance (HEP) model to explore the impact of cognitive biases on the clinical and juridical reasoning in cases where insanity evaluation was requested. Indeed, as the technical report on insanity evaluation is considered to be a scientific proof, it is supposed to comply with the Daubert criteria for admissibility of scientific evidence in court to support the judge in reaching a conclusion «beyond any reasonable doubt». However, recent evidence demonstrate that insanity evaluation suffers from a high error rate and low inter-rater reliability. This paper provides an in-depth analysis of the reason of such a low inter-rater reliability, focuses on the influence of cognitive biases and analyses their impact on juridical outcomes. We conclude our analysis by proposing to adopt a multidisciplinary approach that relies on converging evidence to minimize the impact of cognitive bias on the conclusion of insanity evaluation and, as a consequence, on the juridical error. Thanks to this approach it is possible to increase the inter-rater reliability of diagnosis, strengthening the conclusion about insanity with converging data from different methodologies. In this way, it will become very difficult to support the opposite conclusion without falling into logical fallacies.