The logical foundations of forensic science: towards reliable knowledge

The generation of observations is a technical process and the advances that have been made in forensic science techniques over the last 50 years have been staggering. But science is about reasoning—about making sense from observations. For the forensic scientist, this is the challenge of interpreting a pattern of observations within the context of a legal trial. Here too, there have been major advances over recent years and there is a broad consensus among serious thinkers, both scientific and legal, that the logical framework is furnished by Bayesian inference (Aitken et al. Fundamentals of Probability and Statistical Evidence in Criminal Proceedings). This paper shows how the paradigm has matured, centred on the notion of the balanced scientist. Progress through the courts has not been always smooth and difficulties arising from recent judgments are discussed. Nevertheless, the future holds exciting prospects, in particular the opportunities for managing and calibrating the knowledge of the forensic scientists who assign the probabilities that are at the foundation of logical inference in the courtroom.