One topic I find intriguing as a forensic document examiner, and forensic scientist, is the process of reasoning as it applies to evidence evaluation. This site and blog discusses various topics but many relate to reasoning as it applies to FDE and, more generally, forensic science activities.

I use the term ‘logical reasoning’ to refer broadly to the basic process of evaluation used by an examiner when examining evidence as they attempt to address questions posed to them. For obvious reasons it also relates to any actual decision-making that might occur in during that process.  Ultimately, the approach an examiner takes in their reasoning and evaluation will have an impact on all facets of the work.  This includes the choice of wording used to express a ‘conclusion’, ‘outcome’, or ‘opinion’ deriving from the evaluation process.

I hope everyone can and will agree that the evaluation of evidence should be done in a logically coherent manner. One’s beliefs can be considered coherent if, when expressed in terms of probabilities, they conform to the three rules of probability.  Those are the convexity rule, the addition rule and the multiplication rule, in accordance with Lindsey (2007).  More generally, I use the term for reasoning that is both logically sound and applied consistently throughout the entire process.

Of course, any forensic evaluation must be relevant to the specific matter at hand (otherwise, why do it?), explicable, and functionally useful to the recipient of the resulting expert opinion.  All of these are embodied in what is known today as the logical approach to evidence evaluation. 1

I have found that these topics and concepts benefit greatly from discussion and debate.  The blog and FAQ sections of this website is where I intend to put down my thoughts on these, and other, topics.  I will be using the blog or the FAQs to answer questions I have received when giving workshops and via e-mail queries.  Ultimately, I hope the site will be a forum for discussion by practitioners and other interested parties.

Thanks very much, Brent.


  1. Many other terms can be used to describe this including evaluative reporting.