prior probability

https://en.wikipedia.org/wiki/Poème_sur_le_désastre_de_Lisbonne

Hurricane Melissa, which made landfall in south-western Jamaica as the strongest storm to ever hit the Caribbean island nation in modern history, brought to mind Voltaire’s poem on the 1755 Lisbon earthquake.

See also: “The Dialogue between Voltaire and Rousseau on the Lisbon Earthquake: The Emergence of a Social Science View“.

Among the luminaries I met during my recent visit to Puerto Rico was my old colleague and friend Daniel Nina. (Thanks to the good efforts of Orlando Martinez-Garcia, we met at Professor Nina’s home office in Santurce on Thursday afternoon and had dinner at the popular Costa Azul in Manati on Saturday night.) Among other accolades, it is no exaggeration to say that Prof Nina is the island’s most prolific author; pictured below, for example, are just some of the books he has published over the years! Also, he has played a pivotal role in my own intellectual development: it was Nina who introduced me to the late Carlitos del Valle and to two cult classics, Blade Runner (the director’s cut) and The Battle of Algiers.

My wife Sydjia and I were going to spend this past weekend at the tropical Caribe Hilton in San Juan, Puerto Rico, but our close friends Orlando and Mireya invited us to stay with them at their home in the magical town of Manatí, where we explored many beautiful beaches and shared many memorable meals together. (Special shout out to the cozy Restaurante Merced in the quaint little town of Barceloneta, where we dined on Friday night.)

When I endeavour to examine my own conduct, when I endeavour to pass sentence upon it, and either to approve or condemn it, it is evident that, in all such cases, I divide myself, as it were, into two persons; and that I, the examiner and judge, represent a different character from that other I, the person whose conduct is examined into and judged of. The first is the spectator, whose sentiments with regard to my own conduct I endeavour to enter into, by placing myself in his situation, and by considering how it would appear to me, when seen from that particular point of view. The second is the agent, the person whom I properly call myself, and of whose conduct, under the character of a spectator, I was endeavouring to form some opinion. The first is the judge; the second the person judged of. (Adam Smith, Theory of Moral Sentiments, III.i.6)

Quis custodiet ipsos custodes? (Juvenal, Satire VI, lines 347–348)

According to Adam Smith, each person divides himself into two persons. Person #1 is himself (the ego), while Person #2 is an external judge or spectator. Sometimes, Smith refers to this imaginary alter ego as “the man within the breast” (see here, for example), and at other times, he calls him the “impartial spectator” or “supposed impartial spectator” (again, see here). But regardless whether the impartial spectator and the man within the breast are one in the same or are two separate entities (i.e. the key question that my colleagues Daniel Klein, Nicholas Swanson, and Jeffrey Young recently brought to my attention and that I have been writing about this past week), I will now conclude my series on Adam Smith’s impartial spectator with a totally different question: who spectates the impartial spectator? That is, if each person has an internal man within his breast inside him, and if each person’s moral decisions are reviewed by this man within his breast, and (assuming the impartial spectator and the man within the breast are two distinct entities) if this man within the breast is, in turn, checked by a higher-level impartial spectator, then who checks the impartial spectator?

Nota bene: a Rube Goldberg machine is an elaborate chain-reaction-type contraption intentionally designed to perform a simple task in a comically overcomplicated way. 

I concluded my previous post by asking whether the man within the breast and the impartial spectator in Adam Smith’s Theory of Moral Sentiments (TMS) are two separate and distinct entities or whether they are just two different ways of saying the same thing. For reference, let’s call the first possibility “the two-tiered impartial spectator thesis” and let’s call the second possibility “the unitary impartial spectator thesis“.

Let’s assume, for the sake of argument, that Adam Smith indeed proposed a two-tiered system of moral scrutiny in which the man within the breast (the agent) acts as the representative or agent of the impartial spectator (the principal). On one level (the ground-level, so to speak), every man, woman, and child in the world has his or her own individual “man withing the breast” somewhere deep inside them, but on another level (the sky level), there is a global, godlike, and all-seeing impartial spectator, the ultimate moral judge or ethics tribunal from which there is no appeal. If this two-tiered schema is what Smith really had in mind when he revised TMS in 1790, then notice how this method of making moral judgments actually involves three separate actors in all!

1. First off, we have the main subject, a flesh-and-blood person (man, woman, or child) who is deciding on some course of action or inaction, as the case may be.
2. Next, we have the subject’s “man within the breast” (one’s “inner voice” or conscience), who acts as the impartial spectator’s representative.
3. Last but not least, we have the man-within-the-breast’s principal, the impartial spectator, who presumably has the final say on moral matters.

How plausible is this picture, this two- or three-tiered Rube-Goldberg-like system of morality? What, for example, is the division of labor between the impartial spectator (the big man) and the man within the breast (the agent)? Perhaps the job of the imaginary big man is to act as an arbiter: he steps in and calls the shots only when the subject and the man within the breast disagree on the morality of some course of action. Or maybe the role of the impartial spectator is to monitor collusion. On this view, the big man comes into play when the subject and the man within the breast try to collude together to justify some wrongful act. 

Alas, this two-tier picture of moral judgment has a blind spot: why should we listen to the impartial spectator in the first place? Also, why do we need two separate entities — the impartial spectator and the man within the breast; the big man and his agent — to pass judgment on the morality of our actions? I will conclude with some final thoughts in my next post …

As I mentioned earlier this month, my colleagues Daniel Klein, Nicholas Swanson, and Jeffrey Young (KSY) have published a new paper in Econ Journal Watch, and their paper caught my attention because it’s about the impartial spectator in Adam Smith’s Theory of Moral Sentiments (TMS). To the point, KSY claim that this imaginary being is “a universal beholder” who boasts “superhuman knowledge and universal benevolence” (KSY 2025, p. 297). In plain English, the impartial spectator is a deity or some other make-believe godlike entity they call Joy.

Furthermore, in support of this theistic interpretation of Smith’s impartial spectator, KSY put all of their argumentative eggs into one basket: TMS 215.11 or paragraph 11 of page 215 of the Glasgow edition of The Theory of Moral Sentiments. (As an aside, the standard citation of TMS 215.11 would be “TMS, VI.i.11” because this “smoking gun” passage appears in paragraph 11 of chapter 1 of Book 6 of TMS.) Why do Klein, Swanson, and Young put so much weight on this one passage? Because it is in TMS 215.11 (TMS, VI.i.11) where Smith describes the man within the breast as the “representative” of the impartial spectator!

But why, in turn, is this description of the man within the breast in TMS 215.11 such a big deal? Because Smith uses these two terms (the man within the breast and the impartial spectator) interchangeably in the rest of TMS! This discrepancy thus poses a puzzle: is the man within the breast an agent or representative of the impartial spectator? In other words, are they really two separate entities, as implied by TMS 215.11 (TMS, VI.i.11)? Or are they equivalents, i.e. two different ways of saying the same thing?

In short, is it possible to reconcile this discrepancy? If so, how do we square KSY’s interpretation with the rest of TMS? (Or do we square the rest of TMS with KSY’s “smoking gun” passage?) Stay tuned, I will address these key questions in my next post …

One of Adam Smith’s most original ideas in The Theory of Moral Sentiments (TMS) is the “impartial spectator”, but who (or what) is this perplexing and puzzling observer? Thus far, we have seen how the Scottish philosopher refers to this mystery man/enigmatic entity as an arbiter, examiner, and judge (see here), and we have also seen how he uses such jurisprudential words as appeal, judgment, and sentence to describe the workings of this imaginary magistrate (here). But is Smith’s impartial spectator a god, maybe even the all-powerful Christian God?

No, he is not. (Sorry, KSY!) Although Adam Smith uses the words “great judge” multiple times in TMS to refer both to the deity and to the impartial spectator, the Scottish moral philosopher always capitalizes the word Judge when referring to God. For textual reference, quoted below are all seven instances in TMS where Smith uses the phrase “great judge”/”great Judge”:

1. TMS, II.iii.2: “the great Judge of hearts” = “the Author of nature” = [God]

Actions, therefore, which either produce actual evil, or attempt to produce it, and thereby put us in the immediate fear of it, are by the Author of nature rendered the only proper and approved objects of human punishment and resentment. Sentiments designs, affections, though it is from these that according to cool reason human actions derive their whole merit or demerit, are placed by the great Judge of hearts beyond the limits of every human jurisdiction, and are reserved for the cognizance of his own unerring tribunal. (TMS, II.iii.2)

2. TMS, III.ii.32: “a much higher tribunal” and “the great judge and arbiter of [mankind’s] conduct” = “the supposed impartial and well-informed spectator” = “the man within the breast”

But though man has, in this manner, been rendered the immediate judge of mankind, he has been rendered so only in the first instance; and an appeal lies from his sentence to a much higher tribunal, to the tribunal of their own consciences, to that of the supposed impartial and well-informed spectator, to that of the man within the breast, the great judge and arbiter of their conduct.

3. TMS, III.iii.4: “the great judge and arbiter of our conduct” = “the inhabitant of the breast, the man within”

It is not the soft power of humanity, it is not that feeble spark of benevolence which Nature has lighted up in the human heart, that is thus capable of counteracting the strongest impulses of self-love. It is a stronger power, a more forcible motive, which exerts itself upon such occasions. It is reason, principle, conscience, the inhabitant of the breast, the man within, the great judge and arbiter of our conduct. It is he [the man within the breast] who, whenever we are about to act so as to affect the happiness of others, calls to us, with a voice capable of astonishing the most presumptuous of our passions, that we are but one of the multitude, in no respect better than any other in it; and that when we prefer ourselves so shamefully and so blindly to others, we become the proper objects of resentment, abhorrence, and execration.

4. TMS, III.iii.43: “the great Judge of the universe” = “that Divine Being” = [God]

A true party-man hates and despises candour; and, in reality, there is no vice which could so effectually disqualify him for the trade of a party-man as that single virtue. The real, revered, and impartial spectator, therefore, is, upon no occasion, at a greater distance than amidst the violence and rage of contending parties. To them [the contending parties of politics], it may be said, that such a spectator scarce exists any where in the universe. Even to the great Judge of the universe, they impute all their own prejudices, and often view that Divine Being as animated by all their own vindictive and implacable passions. Of all the corrupters of moral sentiments, therefore, faction and fanaticism have always been by far the greatest.

5. TMS, VI.ii.1.22: “the great judge and arbiter of our conduct” = the man within the breast = the supposed impartial spectator

In what cases friendship ought to yield to gratitude, or gratitude to friendship; in what cases the strongest of all natural affections ought to yield to a regard for the safety of those superiors upon whose safety often depends that of the whole society; and in what cases natural affection may, without impropriety, prevail over that regard; must be left altogether to the decision of the man within the breast, the supposed impartial spectator, the great judge and arbiter of our conduct. If we place ourselves completely in his situation, if we really view ourselves with his eyes, and as he views us, and listen with diligent and reverential attention to what he suggests to us, his voice will never deceive us. We shall stand in need of no casuistic rules to direct our conduct.

6. TMS, VI.iii.1: “the great judge and arbiter of conduct” = the supposed impartial spectator = the great inmate of the breast

Regard to the sentiments of other people, however, comes afterwards both to enforce and to direct the practice of all those virtues; and no man during, either the whole of his life, or that of any considerable part of it, ever trod steadily and uniformly in the paths of prudence, of justice, or of proper beneficence, whose conduct was not principally directed by a regard to the sentiments of the supposed impartial spectator, of the great inmate of the breast, the great judge and arbiter of conduct. If in the course of the day we have swerved in any respect from the rules which he prescribes to us; if we have either exceeded or relaxed in our frugality; if we have either exceeded or relaxed in our industry; if, through passion or inadvertency, we have hurt in any respect the interest or happiness of our neighbour; if we have neglected a plain and proper opportunity of promoting that interest and happiness; it is this inmate who, in the evening, calls us to an account for all those omissions and violations, and his reproaches often make us blush inwardly both for our folly and inattention to our own happiness, and for our still greater indifference and inattention, perhaps, to that of other people.

7. TMS, VI.iii.25: “the great demigod within the breast, the great judge and arbiter of conduct”

The wise and virtuous man directs his principal attention to the first standard; the idea of exact propriety and perfection. There exists in the mind of every man, an idea of this kind, gradually formed from his observations upon the character and conduct both of himself and of other people. It is the slow, gradual, and progressive work of the great demigod within the breast, the great judge and arbiter of conduct.

To recap, Smith conjoins the words great and judge multiple times in TMS to refer to no less than three different entities! Sometimes, Smith’s “great Judge” (with a capital “J”) refers to the “author of nature” or “Divine Being”, i.e. God. (See passages 1 and 4 above.) At other times, however, this “great judge” (lower case “j”) simply refers to “the inhabitant of the breast, the man within”, i.e. our inner voice or conscience. (See, for example, passage 3 above.) But most of the time, Smith uses the words “great judge” to refer not only to the man or “inmate” within the breast but also to “the supposed impartial spectator.” In this set of passages (see passages 2, 5, 6, and 7 above), Smith equates the “supposed impartial spectator” with the man within the breast.

In short, Smith’s “supposed impartial spectator” is not God. He is the man within the breast, and the role of this imaginary magistrate is to judge the morality of our actions. But is there a higher-level impartial spectator, separate from Smith’s “supposed impartial spectator” or man within the breast? My colleagues Daniel Klein, Nicholas Swanson, and Jeffrey Young (KSY) say there is (see here) based (mostly) on a single passage in TMS (TMS, VI.i.11). Stay tuned, for I will revisit that crucial passage in my next post …