prior probability

It’s my favorite week of the spring semester. I get to stay home, ignore emails, and spend time with my family. I can also devour as many books and scholarly papers as I want. Among many other things, I am reading the following works during my spring break:

1. “La tregua” by Mario Benedetti (a beautiful novella by one of my favorite late Latin American authors).
2. “On inequality” by Harry G. Frankfurt. (Professor Frankfurt is one of my favorite contemporary philosophers. In fact, I have already read three of his short books, including “The reasons of love”, “On truth”, and “On bullshit”, so I am looking forward to reading his latest tome as well.)
3. “Frank Ramsey: a sheer excess of powers” by Cheryl Misak. (I just finished this intellectual biography and will be writing a review shortly.)
4. “Acknowledgements as a window into legal academia” by Price & Tietz (an “empirical study” of acknowledgment footnotes in law review articles).
5. “The ethical algorithm” by Roth & Kearns (waiting for my copy to arrive).

To understand the “base rate fallacy” in the Coronavirus context, compare the frequency of “media mentions” of various recent viruses (top image) with the actual number of infections (bottom image) caused by each of these viruses. See also this recent essay on “probability neglect” by my colleague Cass Sunstein.

Why does politics make people so damn stupid? Shout out to Frederick M. Hess and Brendan Bell for their compelling critique of socialist statistics and progressive naiveté. Here is my favorite quote from their excellent piece: “Like data on Chinese economic growth or North Korean voting rates, Cuban literacy-rate data are only compelling to those inclined to believe authoritarian regimes.” File under: we won’t get fooled again (with apologies to my all-time favorite rock band).

In honor of International Women’s Day (8 March 2020), I am posting Nelson Shanks’s oil-on-canvas portrait of Ruth Bader Ginsburg, Elena Kagan, Sandra Day O’Connor, and Sonia Sotomayor, the first four women to serve on the Supreme Court of the United States. More details about this elegant portrait are available here, via Politico.

Having now finished the first half of Cheryl Misak’s intellectual biography of Frank Ramsey (“A Sheer Excess of Powers”), I am especially struck by what Ramsey (pictured below) accomplished before reaching his 19th birthday. In particular, in the space of one month (January of 1922), Ramsey published a devastating critique of left-wing “social credit” proposals, akin to the “universal basic income” schemes of our times; he published a detailed review of John Maynard Keynes’s Treatise on Probability, a review that demolished Keynes’s approach to probability; and he not only translated Ludwig Wittgenstein’s now-famous Tractatus–which is considered to be one of the most important works of modern philosophy–his translation was approved by the demanding and ornery Wittgenstein himself!

Over a century ago, the legal giant Oliver Wendell Holmes invited us to look at the law through the lens of probability theory, or in Holmes’s own immortal words: “The prophecies of what the courts will do in fact, and nothing more pretentious, are what I mean by the law.” Ironically, few legal scholars have taken up Holmes’s intriguing invitation. During the last ten years (2011-2020), however, I authored the following papers in which I applied Bayesian probability to various aspects of law and culture:

1. A Bayesian Model of the Litigation Game (2011), in which I develop a Bayesian model of litigation.
2. Visualizing Probabilistic Proof (2013), in which I use Bayesian methods to solve the “blue bus problem” in evidence law.
3. Finding Santiago (2015), in which I focus on Hemingway’s hero in “The Old Man and the Sea” and explore the inner workings of the old man’s mind through a probabilistic or Bayesian lens.
4. Judge Hercules or Judge Bayes? (2016), in which I use Bayesian methods to solve Newcomb’s Problem.
5. Probabilistic Interpretation II: The Case of the Speluncean Explorers (2017), in which I examine Lon Fuller’s famous fictional case from a Bayesian perspective.
6. A Bayesian Analysis of the Hadley Rule (2019), one of the papers in this fine collection of essays, in which I examine the rule of Hadley v. Baxendale from a Bayesian perspective.
7. The Case for Bayesian Judges: Putting Posner and Vermeule into Practice (in press), in which I develop a simple Bayesian model of adjudication.