Brian Potter
Author, Construction Physics · Senior Fellow, Institute for Progress
aka Construction Physics
“Overall, I found that federal laws mostly do what they're expected to do. But a substantial fraction of them — around 11% — diverge significantly, having either much smaller or much larger effects than originally predicted.”
“A law will create or modify some capability — an organization, a program, a rule that must be followed — aimed at accomplishing some particular thing. But once that capability is out there in the world, people might take advantage of it in different ways, finding uses for it that the creators of that capability never expected.”
“Changing the rules for designating a 'nationally recognized' credit rating agency, as the 2006 Credit Rating Agency Reform Act did, did nothing to disrupt the market share of the existing agency oligopoly.”
“It is, of course, notoriously hard to predict the long-term effects of new technologies. With laws, it seems like predictions are substantially easier. But divergences still exist.”
“Because of this, I expect there to be errors in various evaluations, and I would regard these results as preliminary.”
Brian Potter
One-line summary: Author of the Construction Physics newsletter; writes quantitative base-rate analyses of infrastructure, construction, and regulation — the source of this vault's legislative-divergence base rate.
What they're known for
Construction Physics is a long-form analytical newsletter on why building things is hard and expensive — construction productivity, infrastructure cost disease, permitting friction, and the industrial economy. Potter's method is to take a question usually argued anecdotally and put a number on it, then publish the method and the caveats. He is a senior fellow at the Institute for Progress and has co-written on NEPA with Alec Stapp.
Why they matter to stock-market
Potter supplies base rates for the policy layer of this project's chains, which is otherwise the layer most exposed to narrative reasoning. Many of this book's forcing functions are statutes — permitting, industrial policy, drug-pricing rules, retirement-account flows — and the standard failure mode is to reason from a law's stated intent straight to a market effect. Potter's scoring of 239 federal laws (legislative-divergence-base-rate) gives the distribution that reasoning should be anchored to: ~89% of laws land roughly where expected, ~11% diverge substantially, and the divergences are asymmetric rather than reliably amplifying.
His two canonical cases are directly load-bearing here: NEPA (the permitting friction now gating datacenter, grid, and fab construction, from a provision that got "neither debate, nor opposition, nor affirmative endorsement") and the 401(k) (the statutory origin of the defined-contribution flow this project trades, scored at passage as having "a 'negligible effect upon budget receipts'").
He is also unusually honest about his own method's limits, which is why the base rate is usable — he flags the AI-scoring, the rubric artifact, and calls the results "preliminary" himself.
Said
Speaker-attributed claims extracted from diarized sources. Each bullet mirrors one entry in quotes: frontmatter — keep them in sync.
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On legislative-divergence-base-rate:
"Overall, I found that federal laws mostly do what they're expected to do. But a substantial fraction of them — around 11% — diverge significantly, having either much smaller or much larger effects than originally predicted." — 2026-07-16-feed-construction-physics-how-predictable-are-laws (2026-07-16)
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On legislative-divergence-base-rate — the mechanism of divergence:
"A law will create or modify some capability — an organization, a program, a rule that must be followed — aimed at accomplishing some particular thing. But once that capability is out there in the world, people might take advantage of it in different ways, finding uses for it that the creators of that capability never expected." — 2026-07-16-feed-construction-physics-how-predictable-are-laws (2026-07-16)
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On legislative-divergence-base-rate — the converse, which is the falsifier:
"Changing the rules for designating a 'nationally recognized' credit rating agency, as the 2006 Credit Rating Agency Reform Act did, did nothing to disrupt the market share of the existing agency oligopoly." — 2026-07-16-feed-construction-physics-how-predictable-are-laws (2026-07-16)
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On legislative-divergence-base-rate — the summary judgment:
"It is, of course, notoriously hard to predict the long-term effects of new technologies. With laws, it seems like predictions are substantially easier. But divergences still exist." — 2026-07-16-feed-construction-physics-how-predictable-are-laws (2026-07-16)
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On his own method's limits — the reason the base rate is citable rather than oversold:
"Because of this, I expect there to be errors in various evaluations, and I would regard these results as preliminary." — 2026-07-16-feed-construction-physics-how-predictable-are-laws (2026-07-16)
Sources
- 2026-07-16-feed-construction-physics-how-predictable-are-laws — "How Predictable Are Laws?" (2026-07-16). Multi-context source (also
threads/politics).