Psychological assessment in forensic settings: new methodological conceptions and ethical considerations

Forensic psychological and psychiatric evaluations-understood here as assessments addressing legally operative questions such as, for instance, competency to stand trial, criminal responsibility (sanity), violence risk, but also those on legal capacity and child custody-must meet stringent standards of scientific rigor, transparency, and replicability, yet the reasoning processes underlying clinical formulation require further theoretical articulation. This paper operates at an explicitly metatheoretical level: it does not propose a new clinical procedure, but an epistemological framework grounded in C. S. Peirce's theory of abduction. Abduction designates a third form of inference, irreducible to both induction and deduction: whereas deduction derives a necessary conclusion from a rule, and induction generalizes a rule from observed cases, abduction moves from a surprising fact to the most plausible explanatory hypothesis-a provisional conjecture that requires deductive and inductive testing. Within this framework, forensic case formulation is reconceptualized as an iterative, multi-level abductive process in which idiographic formulations must be systematically anchored to nomothetic data, safeguarded by dual-process reasoning and multimethod and Process-Focused assessment against distortions such as forensic confirmation bias, first-impression effects, and malingering. A novel theoretical contribution is a fractal model of abductive reasoning: clinical inference replicates its structure from micro-abductions on individual signs, through meso-abductions on diagnostic patterns, to macro-abductive formulations. Diagnostic errors can be understood as a "collapse of the fractal." Three vignettes from Italian proceedings illustrate the framework. The paper concludes with methodological and ethical recommendations, arguing that diagnostic error in forensic contexts carries both epistemic and ethical consequences.