Sam Enright is involved in innovation policy at Progress Ireland, a Dublin-based independent think tank. He also manages a publication called The Fitzwilliam. Of particular interest to us, on his personal blog, he shares a well-received link roundup links; the following is an edited version of his Links for April.
Blogs and Short Links
1. Mourning the loss of Robert Skidelsky. Unfortunately, I only managed to read the abridged version of his three-volume work on Keynes, which are unfortunately hard to come by in paperback. Someone really should organize a reprint. A quote from Skidelsky’s Money and Government (2018) captures his insights:
Ronald Coase reminisced about the English economist Ely Devons, who remarked, ‘If economists wanted to study horses, they wouldn’t observe horses directly. Instead, they’d theorize, “What if I were a horse?” and conclude that they would optimize for utility.’ This humorous assertion sheds light on the economic method.
I discovered this quote while exploring what Rebecca Lowe has been reading. The first selection in her roundup is this essay by T.S. Eliot on literary criticism. She read it during a mini-conference on Eliot in St. Louis, Missouri, organized by Sebastian Garren and inspired (I’m proud to add) by the Fitzwilliam Milton Friedman conference. I’m not usually one for emojis, but: 🥹
2. David Friedman responds to my essay about his father. Most sources I consulted (including biographies and The New Yorker) have stated that Milton Friedman stood at 5 feet tall. Interestingly, David claims his father was 5’3”, and I have no grounds to contest this. So what’s happening with these differing accounts? There are numerous photos of Milton alongside individuals of known heights, and three inches is no trivial difference. This could be a significant oversight. Additionally, for those who thought I was overly harsh in my initial post, I mentioned Milton Friedman’s height because he often seemed to take pride in being shorter than average. I salute all short kings.
3. Gavin Leech provides insights on the current status of Chinese AI. He suggests that they are approximately a year behind the West; however, since his post was published in November 2025, that assessment may now be outdated. Still, the read is worthwhile, especially his analysis of how China collects knowledge about cutting-edge models from the open internet.
4. Nicholas Decker argues that Steven Berry, Jerry Hausman, and Ariel Pakes deserve the Nobel Prize in economics. His piece also offers valuable insights into the Hausman test for distinguishing between fixed and random effects estimation in panel data, a topic that perplexed me as an undergraduate.
5. Stephen Malina has a collection of links. My favorite entry features Afra Wang’s story about a vibe coder in Beijing. It’s notable that this quote originates from someone named Liu Xiaopai, supporting Dan Wang’s thesis that “no two peoples are more alike” when comparing Americans and Chinese:
“For the past twenty years, my software-building journey has been heavily influenced by Paul Graham’s Hackers & Painters. His core argument is that the software industry represents the best business in the world due to its near-zero marginal costs. Similar to how painters create, so do software developers, engaging in creation rather than mere construction. These ideas have been pivotal for me. I also appreciate Tools of Titans and Tribe of Mentors by Tim Ferriss.”
6. An archive of the books mentioned on the Conversations with Tyler podcast.
7. Shruti Rajagopalan reports on Delhi’s recent AI Summit. Do check out Shruti’s Substack and her podcast, as both are invaluable resources.
Music and Podcasts
1. Tyler Cowen and Alex Tabarrok discuss the history of options pricing. I’m intrigued by how polymath economists (often French) produced work so advanced that their Anglo counterparts struggled to grasp it for decades. For instance, Augustin Cournot applied the concept of Nash equilibrium as early as the 1830s, while Louis Bachelier derived Brownian motion equations five years prior to Einstein’s independent rediscovery of them, laying down the fundamental concepts of Black-Scholes theory over seventy years earlier.
2. Joe Studwell discusses African economic development. I haven’t yet read How Africa Works, but it’s on my list. Perhaps we might hold a special edition on African economic development in the reading group.
3. Rebecca Lowe and Tyler Cowen explore the definition of freedom. The engaging format has the host and guest delve into a philosophically rich term to reach a workable ‘definition’. If I were ever a guest on such a podcast, I would enjoy discussing terms like ‘alignment’ or ‘causality’.
4. Talking Heads, Speaking in Tongues is a highlight. My top track here is Moon Rocks, while This Must Be the Place doesn’t resonate with me as much. Intriguingly, Brian Eno did not produce this album, having taken the reins for the previous three albums. I understand there was some tension since he was leaving a notable impact.
5. The Clash, Combat Rock. Critical consensus views this album as weaker than either London Calling or The Clash. However, Rock the Casbah is iconic, and it seems an apt time for satirical reflections on Ayatollah Khomeini’s decrees. I also discovered that Straight to Hell is the Vietnam protest song sampled in Paper Planes, which I find fascinating.
6. Mingus Big Band, The Charles Mingus Centennial Session. I am a huge fan of Charles Mingus; the Mingus Big Band was created by his widow over a decade after his passing. The opening performance of Work Song (Break the Chains) is extraordinary, which can be confusing as it differs from the Nat Adderley jazz standard. Interestingly, the trombonist featured in this album is the internet public intellectual Coleman Hughes.
Books and Papers
1. Dave Donaldson, Railroads of the Raj: Estimating the Impact of Transportation Infrastructure. This paper stands as one of the most remarkable in recent economics literature; here’s what Kevin Bryan says regarding Dave Donaldson’s well-deserved John Bates Clark Medal. This work also made Nicholas Decker’s list of 11 favorite economics papers. During his PhD, which spanned eight years, Donaldson painstakingly digitized 1.5 million data points from (largely handwritten) colonial archives. This effort focused on determining transportation costs in British India by analyzing local price variations in salt, a remarkably uniform good. With this information, he estimates a parameter θ, indicating the elasticity of trade volume concerning price. By integrating this data with an existing general equilibrium model of trade, he accurately gauges the welfare effects of railroad expansion in the Raj.
While the methodology is brilliant, the challenge remains that railroad placement can be endogenous; perhaps railways were only constructed in prosperous regions that would fare well anyway. A more compelling approach would involve demonstrating that equal candidates for railroads that weren’t developed—perhaps due to random circumstances—did not experience corresponding benefits. This is essentially how Donaldson conducts a placebo test. However, this part of the paper still raises skepticism, as the reasoning for why certain lines were not built could distort the income picture.
2. Dave Donaldson and Richard Hornbeck, Railroads and American Economic Growth: A “Market Access” Approach. This paper revisits Robert Fogel’s seminal 1964 study on railroads’ role in American economic history. Fogel argued that railroads were not essential for growth in the 19th century, utilizing the “social savings” approach. By contrasting the actual quantity moved by new technologies with what it would have cost using the next-best transportation method, he demonstrated that railroads and canals had a surprising degree of substitute compatibility. Fogel estimated that the absence of railroads in 1890 would have reduced GNP by only 2.7%, a significantly lower figure than many economists predicted.
3. Tyler Cowen’s The Marginal Revolution: Rise and Decline, and the Pending AI Revolution. More of a monograph than a book, it can be accessed for free here. I’m still trying to optimize how to leverage Tyler’s AI integration beyond merely uploading the EPUB and asking questions.
The first section of The Marginal Revolution offers an intellectual history of the ‘marginal revolution’ of 1870s economics, led by William Stanley Jevons, Léon Walras, and Carl Menger. Hollis Robbins’ review offers a succinct overview:
As the 19th century progressed, statistics evolved along two paths: the rise of marginalism, highlighting that economic value stems from the impact of additional units under fixed conditions (such as an extra loaf of bread or hour of labor), and averageism, which posits that aggregates are best represented by averages. Innovations like Adolphe Quetelet’s “average man” and William Stanley Jevons’s index number calculations exemplify this evolution. Tyler believes that marginalism and averageism function as a cohesive unit, enhancing one another, with averages becoming central to measurement while marginal reasoning aids in interpreting those measurements.
The third chapter elucidates why the development of marginalism, despite its apparent simplicity, took considerable time. Tyler draws parallels between economics and geology as fields that, while conceptually straightforward, are characterized by historical inertia. He also raises a sociological perspective: since every competent economist recognized marginalism, the field veered towards more technical pursuits such as econometrics and empirical analysis.
Additionally, Tyler touches on early influencers of marginalism, including Jules Dupuit. Notably, much of marginalist theory reemerged independently through the contributions of Irish polymath Dionysius Lardner in his 1850 work focused on railway economics. It’s astonishing that this detail didn’t surface during our Irish railway economics event. If anyone is interested in writing about Lardner for The Fitzwilliam, please reach out!
A particularly engaging anecdote appears on page 43:
In the 1860s, Jevons created a Logical Abacus, or “logical piano,” an early computing device capable of performing certain logical operations faster than humans. Today, it resides at the Museum of the History of Science in Oxford.
As is typical with Tyler’s writing, his intentions can sometimes be elusive. Nonetheless, I gathered that the ‘marginal revolution’ made economic concepts feel more comprehensible than they truly are. While sophisticated economic models may hold utility temporarily, they often lose their predictive capacity. The capital asset pricing model (CAPM), a significant model in 20th-century asset pricing, holds a critical parameter, β, representing an asset’s sensitivity to market movements. A substantial body of literature culminating in Fama and French (1992) indicates that β lacks predictive power. Today, machine learning algorithms that identify statistical patterns and incorporate minimal theoretical frameworks outperform traditional financial models.
Two possible explanations arise:
- CAPM has always been flawed.
- CAPM accurately described the past, but no longer applies.
It’s a bit of both. Artificial intelligence reveals that our previous understanding was not as robust as we assumed; conversely, economics remains a viable discipline, contributing to our grasp of certain topics. It’s plausible that the world has genuinely become less interpretable over time.
Marginalism largely consists of mathematical identities concerning first-order conditions and optimization. Tyler refers to this as “tautological marginalism.” He presents the idea of “intuitive marginalism,” proposing that these tautological elements are indeed significant and that reasoning “at the margin” proves useful across various applications, such as Jevons paradox. While our intuitive understanding of marginalism may wane in explaining the world, Tyler posits that it will persist in future models’ frameworks (page 119):
“The training of Large Language Models (as with other forms of AI) will enshrine marginalism into their foundational concepts, as these models train on texts that acknowledge marginalist principles… marginalism will endure, but we will automate it.”
The Straussian interpretation of this monograph suggests that Tyler wrestles with his identity as an economist in his sixties, having witnessed the transformative impact of software consumption across all spheres, including in his professional realm. Many of my economist friends now lament not pursuing mathematics or computer science during their undergraduate years. Economics has seen various intellectual paradigms rise and fall, whether due to their intrinsic flaws or their confined applicability to specific phenomena throughout particular timeframes. This includes schools Tyler holds in high regard, such as Chicago price theory and Mason public choice theory. His sense of wistfulness surfaces prominently on page 106:
“Sadly, price theory is diminishing in relevance, taking marginalism along with it. Previously, certain graduate programs emphasized the axiomatic approach to microeconomics, while others (like the University of Chicago, UCLA, and the University of Virginia) preferred price theory. These days, the axiomatic methods seem to dominate, with my own George Mason University being something of an exception.”
Lastly, here are some interesting snippets: regarding the increasing mathematical complexity of economics, we find this quote from Shengwu Li:
“When someone asks you to provide an economic intuition for that result, what they really mean is, ‘Can you explain that using mathematical concepts introduced to economics over twenty years ago?’”
Corollary: Topkis’ theorem counts as economic intuition, along with virtual values and eigenvalues.
On the elasticity of abortions (page 31):
“A hundred-mile increase in distance to the nearest abortion clinic correlates with a 25% reduction in abortions.”
In the latest instance of “economists have predicted nine out of the last five recessions,” I learned that there is indeed a sunspot theory related to macroeconomics (page 59):
“William Stanley Jevons had posited that business cycles occur with a typical regularity of about ten and a half years. Jevons matched this cycle duration with those of solar periods, theorizing a connection that he could never adequately substantiate.”
I declare William Whewell as the Victorian polymath of the month (page 103):
“Alfred Lord Tennyson referred to him as ‘a lion-like man.’ [William] Whewell was a true polymath with contributions spanning mechanics, physics, geology, astronomy, mathematics, and poetry. As an Anglican priest, he translated works by Goethe and Grotius and spearheaded a groundbreaking citizen science initiative to study ocean tides. He was instrumental in persuading Darwin to assume the duties of secretary for the Geological Society of London, acknowledging geology’s importance to Darwin’s evolutionary theory. Whewell’s significant work was his 1837 multi-volume History of the Inductive Sciences, from their Earliest to the Present Times, which, although largely forgotten today, held immense influence in its time. He also coined terms like scientist (in 1833), physicist, linguistics, consilience, catastrophism, uniformitarianism, and astigmatism, showcasing an impressive legacy. Notably, he proposed the terms anode, cathode, and ion to Michael Faraday.”
Films and Videos
1. Tom Moore and Nora Twomey’s The Secret of Kells. This beautifully crafted animated film tells the story of the Book of Kells’ creation, resting on the legend that the manuscript began on the isle of Iona, led by St. Colmcille, before its relocation to Kells in County Meath during the 9th century. This film is the initial entry in a trilogy informed by Celtic mythology, inspired by my affinity for the third film, Wolfwalkers. Eventually, I hope to write a more extensive piece about Irish cinema, which boasts many stellar contributions. One standout aspect is that renowned international actors often agree to be part of local projects, possibly for less pay, such as Brendan Gleeson lending his voice to the Abbot of Kells in this production.
Endnotes:
[1] One reason Bachelier struggled is that his thesis advisor, Henri Poincaré, was not impressed by him. Legend has it that Leonard Savage (the figure behind the Savage axioms) once raved about Bachelier in a postcard to Paul Samuelson, which later reached Fischer Black and Myron Scholes, as well as Robert Merton. There’s quite a bit of value in sending postal correspondence!
[2] Interestingly, the unofficial marriage ceremony for Charles and Sue Mingus was “officiated” by poet Allen Ginsberg.
[3] If I’ve understood correctly, Coleman Hughes plays on tracks 1, 2, 9, and 11.
[4] Remarkably, the timeline for top-tier economics journal publications has stretched beyond belief. ‘Railroads of the Raj’ circulated as a working paper since 2010 but wasn’t published in the American Economic Review until 2018, following 17 years of research. Interestingly, this was a year after Donaldson received the John Bates Clark medal, largely due to this paper’s significance.
[5] While detailed info may be sparse online, the Indian government’s railway page contains some fascinating resources regarding expansion under the Raj. However, as has been my experience with Indian trains, that page is currently broken.
[6] There are informative discussions about Jevons’ contribution to constructing price indices, particularly his preference for the geometric mean over the arithmetic mean in this context. Refer to page 58 for further insights.
