Abstract
In criminal trials at common law there is an apparent clash of legal principles. On the one hand, a jury cannot convict an accused except on a finding of guilt “beyond a reasonable doubt.” On the other hand, juries base their verdicts on what they take to be the best “theory of the case”. A theory of a case is a conjecture that best explains the evidence led at trial. Theories of the case are therefore exercises in abduction. Since abduction is intrinsically conjectural, it is difficult to see how any theory of the case could meet the proof standard of guilt beyond a reasonable doubt. The present chapter offers a solution of this apparent paradox.
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- 1.
Although there is some overlap between them, not everything that holds in the common law tradition holds in the tradition of Germano-Roman law.
- 2.
This is undertaken in (Woods, 2007b).
- 3.
Consider a commonplace sort of case. I’ve forgotten how to spell “accommodate”. Does it have one “m” or two? If I walk from my desk to the dictionary on the other side of the study and look up its spelling, then I have availed myself of response (1). On the other hand, if I decide to replace “accommodate” with a synonym that I can spell – say “provide for” – I have made a response of type (2).
- 4.
- 5.
The thesis that activation is essential to abduction is discussed in greater detail in Gabbay and Woods, (2005).
- 6.
Non-explanatory modes of abduction appear prominently in “reverse mathematics” pioneered by Harvey Friedman and his colleagues, e.g., Friedman and Simpson (2000). The idea of reverse mathematics originates with Russell’s notion of the regressive method in mathematical logic (Russell, 1907), and is also present in some remarks of Gödel (1944, 1990).
- 7.
Informally, what this means is that H has a no more plausible and relevant rival constituting a greater degree of subjunctive attainment of T. Elucidating condition (5) is one of the more difficult tasks facing a logic of abduction, but it won’t be our focus here. See Gabbay and Woods (2006).
- 8.
One should add: “if ever”.
- 9.
Still, such cases are rare. It is much more common for defendants, in jurisdictions where it is permitted, to “plead out” in return for an antecedently agreed-upon lighter sentence.
- 10.
Actually, this touches on a vexing problem for legal theory and legal practice alike. In the common law tradition, the prosecution’s burden is to prove every element of the case required for conviction. A jury’s duty is to determine whether the prosecution has met this burden. So from this perspective, the juror’s duty is to assess the prosecution’s theory of the case, which involves determining whether the prosecution’s abduction has the requisite strength and whether the subset of the evidence it purports best to explain is an adequate evidential basis for an abduction of guilt. On the other hand, the jury also has a duty to determine whether, having heard all the evidence, it is proved beyond a reasonable doubt that the accused is guilty as charged. This is a broader mandate than the duty to determine whether the prosecution’s case has met the burden of proof. Let us say this as simply as possible. The burden of proof and the standard of proof place on jurors different and not always compatible tasks. It is easy to see that, in fulfilling its duty to ascertain whether the Crown has met its burden, a jury might well reject the Crown’s case and thereby find that the prosecution has failed to meet the burden of proof. But the jury might also, and with consistency to its total obligations, determine that the evidence heard contains an acceptable subset that supports a verdict of guilty in fulfillment of the standard of guilt beyond a reasonable doubt. Perhaps this doesn’t happen often. But it is perfectly possible for a stupid or lazy prosecutor to fail to find a winning case in his own filtering of the evidence. Upon reflection, it is right and proper that standard of proof supercede the burden of proof. And, of course, it would be neater if the burden of proof were revised to reflect the necessity that every element of the case for conviction be proved to the requisite degree by the subset of the evidence that the jury accepts as operational, never mind whether the Crown actually succeeds in making that case.
- 11.
Klotter (1992) defines circumstantial evidence as follows: “Direct evidence proves a fact without inference … Circumstantial evidence is evidence from which a fact is reasonably inferred but not directly proven.” (pp. 67–68).
- 12.
But here, too, there are contradictory rulings. Notwithstanding that the U.S. Supreme Court eliminated it from federal trials, the following instruction regarding circumstantial evidence is still in force in the state courts of California.
However, a finding of guilt as to any crime may not be based on circumstantial evidence unless the proved circumstances are not only (1) consistent with the theory that the defendant is guilty of the crime, but (2) cannot be reconciled with any other rational conclusion … Also, if the circumstantial evidence permits two reasonable interpretations, one of which points to the defendant’s guilt and the other to innocence, you must adopt that interpretation that points to the defendant’s innocence, and reject that interpretation that points to guilt. (CALJIC 2.01. Emphases added).
See Holland v. U.S. (1954) for the opinion that “the instruction on circumstantial evidence is confusing and incorrect.”
- 13.
(1999), 9 C.R. (5th) 1 (S.C.C.)
- 14.
Ennis (1996) reports the experience of its American author as a juror in a murder trial. Robert Ennis is a leading analyst of critical thinking (and, in many common law jurisdictions, would have been excluded from jury-duty on that account – perhaps the courts in Illinois don’t regard critical thinking as an expert discipline). Ennis tells us that the presiding judge refused the jury’s request for a definition of reasonable doubt, replying that “There is no definition of proven beyond a reasonable doubt. Do the best that you can” (p. 320). Ennis then proposed the following definition to his colleagues, which they accepted (and acted on):
To say that something is proven beyond a reasonable doubt is to say that it would not make sense to deny that thing (p. 320).
After the trial, Ennis thought better of this definition and replaced it with:
To say that a conclusion is proven beyond a reasonable doubt is to say that the evidence supports it so strongly that it would not make good sense to deny it (p. 326).
In the end, the jury acquitted the defendant of murder but found her guilty of voluntary manslaughter. Ennis writes “[t]he definition I gave, despite its defects, enabled us to discuss the matter [of the justification of the defendant’s use of force]. In this situation, I believe that the defects in the definition did not affect the argument” (p. 321). Why would this be so? Because, says Ennis, in “giving that definition in that situation, I was not telling people anything they did not already know” (p. 320).
- 15.
It is not too much to say that in common law jurisdictions the question of the teachability of the criminal standard of proof is in substantial disarray. In a significant ruling, the Supreme Court of the United States (In re Winship) found that there was a constitutional obligation that criminal juries were, without exception, to be instructed that guilt beyond a reasonable doubt is necessary for conviction. Given that judges must now tell juries that they are subject to this standard, a question naturally enough arises as to whether judges should also go on to tell juries what the standard means. It bears on this that recently England has abandoned a practice of two centuries of having judges instruct jurors about the meaning of the standard. What brought this about was pressure from legal theorists to the effect that “reasonable doubt could be neither defined, nor uniformly understood, nor consistently applied.” (Laudan, 2006, p. 76) Much the same view prevails in a number of U.S. state jurisdictions. In Oklahoma and Wyoming, to take just two examples, a judge’s instruction on the meaning of the standard is automatic grounds for reversal (Pennell v. Oklahoma,640 P.2d 568 at 570 (1982), and Cosco v. Wyoming, 521 P. 2d 1345 (1974) at 1346). On the other hand, 15 states require that the standard be defined, while most appellate courts discourage the practice. Again, the Seventh Circuit Court of Appeal “admonished district courts not to define ‘reasonable doubt’.” (U.S. v. Martin-Tregora 684 F. 2d 485, at 493 (7th Cir. 1982). In 1994, the Fourth Circuit Court ruled that when a jury asks for a definition of the standard, a judge is at liberty to refuse. (U.S. v. Reives, 114 S. Ct. at 2679 (1994). The U.S. Supreme Court has never managed to decide whether reasonable doubt should be defined, finding that the American constitution is non-committal about whether a definitional obligation exists (Victor v. Nebraska, 114 S. Ct. at 1243 (1980).
- 16.
- 17.
Consider an example from Gigerenzer (2005). An outfielder is making to catch a well-hit fly fall. There are two models for this, only one of which comports with the empirical record. In the one model – not unlike the RDM – he seeks to predict where the ball will land, and moves himself accordingly. This involves calculations of trajectories and the like that no one can make in the time it takes to catch the ball. So instead – this approximates to the NHMM – the fielder moves himself in such a way as to keep the moving ball in the centre of his field of vision. In so doing, he moves to where he needs to be when the ball falls. No doubt what he does conforms to all the mathematical requirements for charting the point of impact, but in actually catching the ball, none of these requirements was actually implemented.
- 18.
See here Woods (2005).
- 19.
- 20.
The qualifier “somewhat” is explained below in Section 9.
- 21.
Notably in judicial determinations of the admissibility of evidence, the Crown’s burden of proof and the presumption of innocence.
- 22.
- 23.
Nor should we lose sight that in common law jurisdictions, most criminal convictions are not appealed, and most appeals are lost. So much for the reversibility of wrongful convictions.
- 24.
For a discussion of The Sleight of Hand Effect (though not under that name) as a general epistemological regularity, see Woods (2005) and Gabbay and Woods (2007).
- 25.
In Ennis (1996), Prof. Ennis reports as follows. Having proferred a definition of proof beyond a reasonable doubt (see note 12), it became apparent that the “other jurors had a degree of special respect for me because they knew me to be a professor and teacher of critical thinking …. So they took my word.” (pp. 320–321). It would appear that, in effect, the jurors found that, although they themselves were mired in model (1), Prof. Ennis operated in the loftier climes of model (2) and, moreover, that the jurors were ready to subordinate their efforts to understand the proof standard to Ennis’ superior command of it. If I am not mistaken, Ennis himself didn’t think this confidence to be misplaced. Of course, with respect to the proof standard itself, Ennis was not operating in the manner of model (2), since, in his own words, he “was not telling people anything they did not already know.” (p. 320) We have no record of any other suggestions that Ennis might have made in the course of their deliberations; so it is not possible to determine whether he presented his fellow jurors with any methods about how to negotiate the requirements of the standard – for example, did he teach them the probability calculus? But it is unlikely that he did. This reflects not so much on the difficulty of bringing NHMM-reasoners up to RDM-speed as on the likelihood that even the author of Critical Thinking was not up to RDM-speed either. None of this is said with the least whiff of criticism. Critical Thinking makes a valuable contribution to sharpening up NHMM-thinking, but it does nothing to set out the routines for negotiating the proof standard. This contrasts, as we saw, with even the elementary example of proof in a simple axiomatic presentation of propositional logic, which is RDM-thinking at full bore. But there is nothing like it in jury rooms.
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Acknowledgement
For helpful correspondence or conversations, I warmly thank the late L.J. Cohen, Robert Ennis, Eveline Feteris, Maurice Finocchiaro, Dov Gabbay, Gerd Gigerenzer, David Godden, David Hitchcock, Erik Krabbe, Lorenzo Magnani, and Patrick Suppes. For technical support, Carol Woods was invaluable, as always.
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Woods, J. (2010). Abduction and Proof: A Criminal Paradox. In: Gabbay, D., Canivez, P., Rahman, S., Thiercelin, A. (eds) Approaches to Legal Rationality. Logic, Epistemology, and the Unity of Science, vol 20. Springer, Dordrecht. https://doi.org/10.1007/978-90-481-9588-6_11
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