I'm going to do my gosh darned best to recap each session of the seminar this yr. Here's Session 1 ...
The objective of session 1 was two-fold: first, to introduce Pennington & Hastie’s “Story Telling Model” (STM) as a mechanism of jury information processing; and second, to establish the “missing likelihood ratio” (MLR) as the heuristic foundation for engaging mechanisms of jury information processing generally.
In the “Self-defense?” problem puts the MLR problem in stark terms.
In the problem, we are presented with a series of facts the significance of which is simultaneously indisputableand highly disputed. What’s undeniable is that each of these facts plainly matters for the outcome. What’s unclear, though, is how.
Rick paused for a period of time after exiting the building and viewed Frank as he approached him from across the street. Was Rick frozen in fear? Adopting a stance of cautious circumspection? Or was he effectively laying a trap, allowing Frank to advance close enough to enable a point-blank fatal shot and create a credible claim of his need to have fired it?
Likewise, Rick emerged from a secured building lobby accessible only by use of an electronic key. Was his failure to seek immediate refuge in it upon spying Frank evidence of his intention to lure Frank close enough to him to make a deadly encounter appear imminent—or would it possibly have put Rick in deadly peril to turn his back on Frank in order to re-enter with use of the electric key?
Were Frank’s words—“What are you looking at, you freak? I’m going to cut your damned throat!”—a ground for perceiving Frank as harboring violent intentions? Or was the very audacity and openness of the threat inconsistent with the stealth that one would associate with an actor intent on robbing another?
Frank had begun to lurch toward Rick moments before Rick fired the shot. Was Frank’s erratic advance grounds for viewing him as a lethal risk or for seeing him as too stupefied by drink to reach Rick at all, much less apprehend him had Rick made any effort to escape?
Rick immediately called 911; doesn’t that show he harbored law-abiding intentions? But doesn’t the calm matter-of-fact tone of his communication show he wasn’t genuinely in fear for his life?
What if we roll back the tape? Rick had read of the string of robberies in his neighborhood; didn’t that give him grounds for fearing Frank? But what did it give him grounds for fear of? One cannot lawfully resort to deadly force to repel the taking of one's property, even the forcible taking of it.
Rick started to carry a concaled gun after reading of the robberies. Was that the reaction of a person who honestly feared for his life—or one of a person who lacked regard for the supreme value of life embodied in the self-defense standard, which confines use of deadly force to protection of one’s own vital physical interests?
In the face of these competing views of the facts, “Bayesian fact-finding” is an exercise in cognitive wheel spinning.
Formally, Bayes Theorem says that a factfinder should revise his prior estimate of some factual proposition or like hypothesis (expressed in odds) by multiplying it by a factor equivalent to how much more consistent a new piece of information is with that proposition than with an alternative one: posterior odds = prior odds x likelihood ratio.
Legal theorists argue about whether this is a psychologically realistic picture of juror decisionmaking in even a rough-and-ready sense.
But as a problem like self-dense helps to show, the Bayesian fact-finding instruction is bootless in a case like Self-Defense.
There the decisionmaking issue there is all about what “likelihood ratio” or weight to assign all the various pieces of evidence in the case.
Do we assign a likelihood ratio “greater than 1” or “less” to Rick’s behavior in buying the gun, in standing motionless outside the building as Frank approached, in failing to seek protection inside the lobby, in placing a call to 911 in the manner he did; ditto for Frank’s tottering advance and his bombastic threat?
Bayes’s Theorem tells us what to do with the likelihood ratio but only after we have derived it—and has nothing to say about how to do that.
This is the MLR dilemma. It’s endemic to dynamics of juror decisionmaking. And it’s the problem that theories like Hastie and Pennington’s Story Telling Model (STM) are trying to solve.
STM says that jurors are narrative processors. They assimilate the facts to a pre-existing story template, one replete with accounts of human goals and intensions, the states of affairs that trigger them, and the consequences they give rise to.
In a rational reconstruction of jury fact-finding, the story template is cognitively prior to any Bayesian updating. That is, rather than being an outcome constructed after jurors perform a Bayesian appraisal of all the pieces of evidence in the case, the template exists before the jurors hear the case, and once activated functions as an orienting guide that motivates the jury to conform the individual pieces of evidenced adduced by the parties to the outcome it envisions.
Indeed, it also operates to fill in the inevitable interstitial gaps relating to intentionality, causation, and other unobservables that form the muscle and sinew necessary to transform the always skeletal trial proof into a full-bodied reconstruction of some real-world past event.
Schematically, we can think of the story template as shaping juror’s priors, as supplying information or evidence over and above what is introduced at trial, and then determining the likelihood ratio or weight to be assigned to all the elements of the trial proof.
Whence the template? Every juror, P&H suggest, comes equipped with an inventory of templates stocked by personal experience and social learning.
The trial is not a conveyor belt of facts presented to the jury for it to use, one-by-one, to fabricate a trial outcome.
It is a contest in which each litigant endavors to trigger as quickly and decisively as possible selection of the most favorable case-shaping template from the jury’s inventory . . . .
Or so one would gather from P&H.
The questions for us, always, about such an account are always 3: (1) is it true; if so (2) what use is it for a lawyer; and (3) what significance does it have for those intent on making the law work as well as it ppossibly can?
What are the answers?
You tell me!