Rational Justice

geebee2

I'm interested in how courts and juries might use rational techniques to arrive at correct decisions on guilt.

In a complex case, it would seem to sensible to assess each component of the prosecution and defence case, and estimate the relative likelihood. If the prosecution case is (say) 100 times more likely than the defence case, then you can say the defendant is guilty beyond reasonable doubt.

I never heard of this being done though. I recently made an analysis of the Massei report into the Amanda Knox case. It looked like this ( see http://massei-report-analysis.wikispaces.com/ for the entire analysis and some insight into the numbers below ).

Event	Prosecution Probability	Defence Probability
Phone at cottage at 22:13	1%	99%
DNA evidence correct	50%	50%
Break in staged to look like Rudy did it vs unstaged break-in	10%	90%
Conspiracy among 3 near strangers with no apparent motive vs burglary gone wrong	5%	95%
Murder weapon was two knives rather than one	10%	90%
Time of death 23:30 vs 21:10 according to empty duodenum	10%	90%

This is perhaps a bit vague. It's not a great example, because in the end I didn't find any credible prosecution evidence. It's not entirely clear what the "probability" numbers here actually are, and whether two columns are needed. But hopefully it shows that the Massei's account of the murder is quite improbable, and there is considerable doubt.

I'm interested in possibly devising a more complete framework for how such an assessment should be done, the pitfalls that need to be guarded against (how uncertain are the probability estimates?), and even views as to how "reasonable doubt" should be quantified.

Perhaps readers would like to make an assessment of other interesting cases, to explore the issues.

Or how would you approach this problem?

I'm interested in how courts and juries might use rational techniques to arrive at correct decisions on guilt.

Event	Prosecution Probability	Defence Probability
Phone at cottage at 22:13	1%	99%
DNA evidence correct	50%	50%
Break in staged to look like Rudy did it vs unstaged break-in	10%	90%
Conspiracy among 3 near strangers with no apparent motive vs burglary gone wrong	5%	95%
Murder weapon was two knives rather than one	10%	90%
Time of death 23:30 vs 21:10 according to empty duodenum	10%	90%

Perhaps readers would like to make an assessment of other interesting cases, to explore the issues.

Or how would you approach this problem?

What is the difference between a cognitive bias and a bound on rationality? I thought those were two ways of framing the same phenomenon.

I like your theory of efficient dark arts. (I hope you call it the efficient-darkart hypothesis.) I think you're right that lawyers are already strongly motivated to exploit all effective dark-arts techniques. I was not suggesting the existence of unexploited yet effective techniques. I was suggesting that changing the "baseline" (is this a specific application of raising the sanity waterline?) may increase the effectiveness of certain techniques, from pointlessness to practicability.

Here it is again, more concretely. There would be no point in constructing a fallacious argument, in the language of Bayesian probability, to persuade someone who had no previous understanding of that language. In the present world, that's almost everyone. So lawyers don't spend much time concocting pseudo-Bayesian sophisms. But if enough people learn about probability theory, it might pay for lawyers to do just that.

Thus educating lots of people in probability could usher in new fallacies. This is what we should expect from giving motivated thinkers new ways to think--they'll think in new ways, motivatedly.

As I understand the term, bounded rationality (a.k.a. rational ignorance) refers to the theory that a person might make the rational (perhaps not our definition of rational) decision not to learn more about some topic. Consider Alice. On balance, she has reason to trust the reliability of her education, and her education did not mention existential risk from AI going FOOM (which she has reason to expect would be mentioned if it was a "major" risk). Therefore, she does not educate herself about AI development or advocate for sensible AI policie... (read more)