prior probability

As a gift to my loyal readers, below are a few of my favorite Internet links that I stumbled upon at various moments during the past two years:

1. Central Intelligence Agency, “Simple Sabatoge Field Manual” (1963)
2. Daniel Crane, “The Law on Christmas” (2021)
3. Jay Daigle, “Paradigms and Priors” (2019)
4. Alice Gribbin, translation of Eugène Delacroix’s “Questions on the Beautiful” (2025/1854)
5. Michael Huemer, “How to Philosophize” (2024)
6. Kevin Kelley, “101 Additional Advices” (2024)
7. Nan Ransohoff, “What virtue is undersupplied today?” (2025)
8. Joan Westenberg, “I Deleted My Second Brain” (2025)
9. Bonus link: “A Charlie Brown Christmas Live”:

Bonus Friday Funny: “Uncle Put More Thought Than Usual into this Year’s Gift Cards” via The Onion.

In my previous post, I explained why Ronald Coase’s reciprocal-harm insight should be treated as an axiom, i.e. an indemonstrable first principle or formal logical expression used in a deduction to yield further results. Today (Merry Christmas!), I will explore what I like to call the domain question: what is the scope of Coase’s axiom? Does it apply to all harms or only to economic harms like the ones discussed in Coase’s original FCC and social cost papers, i.e. the papers in which Coase first introduced his reciprocal-harm model? There are three logical possibilities: narrow, intermediate, and broad.

1. Narrow: economic harms. On one end of the reciprocal-harm domain space are so-called “externalities” or economic harms (see here, for example), i.e. the spillover effects of otherwise lawful or socially-useful business activities such as cattle trespass, noise and vibrations, railway sparks, signal interference, smoking chimneys, etc.: the examples that Coase himself surveys in his FCC and social cost papers. In support of this narrow interpretation of Coase’s axiom one need look no further than the very first sentence of Coase’s social cost paper itself, which begins thus: “This paper is concerned with those actions of business firms which have harmful effects on others.” (Coase 1960, p. 1)
2. Intermediate: involuntary harms. Although the ostensible subject matter of Coase’s FCC and social cost papers is the problem of economic harms (e.g. cattle trespass, noise and vibrations, railway sparks, signal interference, smoking chimneys, etc.), why should we limit the domain of Coase’s axiom in such an artificial or arbitrary way? Why not extend the domain of Coase’s axiom to include all involuntary or unintentional harms more generally? On this intermediate view of the problem of harmful effects, what matters is not the source of any given harm (i.e. whether the harm was generated by a business firm or not); what matters is the intent or motive of the actor who generated the harm: did he (or in the case of a business firm, it) intend to injure another party?
3. Broad: all harms. On the other extreme of the domain space are all harms, not just unintentional harms or accidents but also deliberate and intentional ones. After all, what is a “harm” — whether unintentionally or deliberately produced — but an action or omission that imposes a disutility or cost on another party? (For general philosophical definitions of the concept of harm, see Feinberg 1984; Gert 2004.) On this broad view of harms, what matters is not the intent or motive of the actor producing the harm, i.e. whether the actor acted deliberately or not. What matters is that someone has incurred a disutility or cost without consenting to the imposition of that cost.

Which of these three logical possibilities is the most plausible one? Should it matter whether the harm is an “economic” one? (If so, how does one distinguish “economic” from “non-economic” harms?) Or in the alternative, should the motive of the person or firm producing the harm matter? (If so, why should intentionality matter?) For my part, I see no reason why the domain of Coase’s axiom should be limited to options one or two above; from a purely logical perspective, the domain of an axiom (or a set of axioms) includes anything that can be derived or deduced from that axiom or set.

Feliz Nochebuena; Happy Christmas Eve! As readers of this blog may know, I have long been fascinated with Ronald Coase’s counter-intuitive insight that harms are a “reciprocal” problem. What you may not know, however, is that this simple idea has haunted me since the fall of 1990, my first semester of law school, when I was Guido Calabresi’s torts student at Yale, for it was in one of Guido’s legendary torts lectures that I was first exposed to Coase’s paper The Problem of Social Cost, the landmark work in which Coase introduces his reciprocal-harm model.

Since then, I have published no less than 10 scholarly papers (see here, for example) in which I explore or extend various aspects of Coase’s work, but the one idea that continues to haunt me the most is Coase’s reciprocal-harm thesis. Why has the idea of “reciprocal harms” haunted me for so long? Because if Coase is right, if harms are a reciprocal problem, this proposition would have radical and far-reaching implications for moral and political philosophy. But is Coase right? Are harms really reciprocal? Also, how would we prove (or disprove!) this claim? Is Coase’s model of reciprocal harms falsifiable in the Popperian sense?

Here is where my most recent work-in-progress on reciprocal harms (“Coase’s fable”, available here) comes into play, for I have now decided to describe Coase’s destabilizing insight that harms are a reciprocal problem as an axiom. My reason for making this move is strategic: to sidestep the truth and proof questions I posed above, for axioms are supposed to be self-evident. [On this note, see footnote 6 of my paper, where I define an axiom as “a statement of proposition that is regarded as being self-evidently true”.] I concede, however, that calling Coase’s insight an axiom now opens up a new can of pesky philosophical worms, so to speak. Among these are: why are axioms “self-evident”, and is Coase’s reciprocal-harm model really an axiom?

Regarding these deeper questions, I have found Robert G. Brown’s book-length work on the history and nature of axioms to be helpful. To the point, according to Brown, a physics professor at Duke, an axiom is just a starting point, an assertion or proposition that we simply assume to be true for the sake of argument: “an axiom is not necessarily a self-evident truth, but rather a formal logical expression used in a deduction to yield further results.” [1] In other words, axioms are exempt from the necessity of independent proof: you either accept Coase’s insight as true, as an accurate or useful model of reality, or you don’t.

But even if we are prepared to accept Coase’s reciprocal-harm model as an axiom (in order to sidestep truth and proof questions about the model), we still have an even more important question to address: what is the scope or domain of Coase’s axiom? Does the reciprocal-harm model apply only to economic harms, to involuntary harms more generally, or to all harms? I will address this deeper question in my next post …

[1] Robert G. Brown, Axioms (2007), https://webhome.phy.duke.edu/~rgb/Philosophy/Axioms/axioms/ [https://archive.ph/SrpLc]. See also Yuri Balashov and Alex Rosenberg (editors), Philosophy of Science, London and New York: Routledge (2002), pp. 129-131.

I mentioned in a previous post that my latest work-in-progress “Coase’s fable” is a follow-up to two previous papers I wrote, one titled “Coase’s parable”; the other, “Modelling the Coase Theorem.” Now, as a follow-up to my follow-up (!), I am going to address two additional research questions in my fable paper based on some of the feedback I received this past weekend at the University of Austin:

1. A theorem or an “axiom”? It was the Chicago economist George Stigler who credited Ronald Coase with developing a “theorem”: Coase’s insight about costless bargaining. My focus, by contrast, is on the underlying premise of this so-called theorem — specifically, on Coase’s insight that harms are a reciprocal problem. I will therefore explain why we should refer to this novel insight as an axiom.

2. What is the domain or scope of Coase’s axiom? Next, I will explore the domain of Coase’s reciprocal-harm premise. Does the reciprocal-harm model apply only to economics harms (e.g. so-called “spillover effects” generated by individuals and firms); does it apply to involuntary harms more generally (e.g. cases of mere negligence); or does it apply to all harms?

Stay tuned, for I will further address both of these key questions in my next two posts …

1. Interview with Tyler Cowen, prolific author, globetrotter, and “information monster” extraordinaire.
2. Interview with Alex Guerrero, political theorist and author of Lottocracy (pictured below).
3. Interview with Timothy Snyder, the professor who cried wolf.

That is the title of the paper, available here via SSRN, that I will be presenting this weekend at the Winter Institute for the History and Philosophy of Economics at the University of Austin (UATX). My paper is an updated version of two previous paper I wrote: one titled “Coase’s Parable,” which was published in the Mercer Law Review in 2023; the other, “Modelling the Coase Theorem,” published in the European Journal of Legal Studies in 2013. In my updated paper, I revisit Ronald Coase’s cattle trespass hypothetical and explore the origins of his counter-intuitive insight that harms are a reciprocal problem, an idea that I now call “Coase’s axiom.”

This weekend, I will be attending and presenting my work on Ronald Coase, who is considered the founder of “law & economics,” at the Winter Institute for the History and Philosophy of Economics at the University of Austin (UATX), a private non-profit university founded in 2021 whose motto is “the fearless pursuit of truth.” Stay tuned. I will provide additional updates soon.