This is an examination of similarities and differences between Atocha Aliseda’s semantic tableaux analysis of abduction and Dov Gabbay’s and the present author’s ignorance-preservation model of it. Also discussed is the suitability of these models for the analysis of the logical structure of legal reasoning.

The totality of evidence heard in a trial is usually collectively inconsistent, indeed often jointly incoherent. In those cases in which each party offers its own theory of the evidence, an abduction is forwarded which best explains a coherent subset of the evidence. Since these are themselves often jointly incoherent subsets S and S*, we have the following difficulty. Opposing theories are those which purport best to explain different sets of the evidence. In that sense, they aren’t rival theories. How (...) could they be, since “E best explains S” and “~E best explains S*” could both be true? How can the defence’s theory of the case answer the prosecution’s if it does not in some sense contradict it? Examination of the empirical record suggests that when faced with this kind of incommensurability, jurors form their own evidential subsets, for which they themselves try to furnish seek for the best explanation. This at once raises a difficult question. On what basis does a juror select the evidence which his eventual abduction will best explain? It is well-understood that opposing counsel select their respective evidence-sets tendentiously, with a view to facilitation of the desired abduction. But jurors are sworn to objectivity and impartiality. How, or whether, jurors manage to fulfill this obligation is the subject of this paper. A solution will be proposed that draws on Simulation Theory, which arises from recent psychological research. (shrink)

An agent-centered, goal-directed, resource-bound logic of human reasoning would do well to note that individual cognitive agency is typified by the comparative scantness of available cognitive resources—information, time, and computational capacity, to name just three. This motivates individual agents to set their cognitive agendas proportionately, that is, in ways that carry some prospect of success with the resources on which they are able to draw. It also puts a premium on cognitive strategies which make economical use of those resources. These (...) latter I callscant-resource adjustment strategies,and they supply the context for an analysis of abduction. The analysis is Peircian in tone, especially in the emphasis it places on abduction’signorance-preservingcharacter. My principal purpose here is to tie abduction’s scarce-resource adjustment capacity to its ignorance preservation. (shrink)

In criminal cases at common law, juries are permitted to convict on wholly circumstantial evidence even in the face of a reasonable case for acquittal. This generates the highly counterintuitive—if not absurd—consequence that there being reason to think that the accused didn’t do it is not reason to doubt that he did. This is the no-reason-to-doubt problem. It has a technical solution provided that the evidence on which it is reasonable to think that the accused didn’t do it is a (...) different subset of the total evidence from that on which there is no reason to doubt that he did do it. It lies in the adversarial nature of criminal proceedings in the common law tradition that the subsets of the total evidence on which counsel base their opposing arguments are themselves different from and often incompatible with one another. While this solves the no-reason-to-doubt problem, it does so at the cost of triggering a second problem just as bad. It is the no-rival problem, according to which incompatible theories of the case based on incompatible subsets of the evidence cannot be rivals of one another. If neither party’s case contradicts the other’s then, by the burden of proof requirement, criminal convictions are impossible. Once having generated the dilemma, the object of the paper is to determine how it might be escaped. (shrink)