Induced Innovation and the Habakkuk Thesis — reading pack

Page: https://gautsch.org/research/induced-innovation-and-the-habakkuk-thesis/

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The short version

When Cowen calls Acemoglu a real business cycle theorist, Acemoglu reaches past him for a different ancestor: “Habakkuk was the first one who was about this.” H.J. Habakkuk argued in 1962 that America out-innovated Britain in the 19th century because American labor was scarce and expensive, which pushed American firms toward labor-saving machinery. That is the seed of the whole induced-innovation idea, and it is the intellectual root of Acemoglu’s optimism about falling birth rates.

Relevant transcript excerpt

Source: https://conversationswithtyler.com/episodes/daron-acemoglu-2/

Annotated transcript: https://gautsch.org/research/#a19

COWEN: Does that mean you’re not really such a Keynesian? Because the fertility crisis, aggregate demand, aggregate supply, they’re shrinking forever. A Keynesian or a supply-sider could get quite worried. Paul Romer, the market size is shrinking, he should get quite worried. In a funny way, you end up at a real business cycle point of view where as long as the induced innovation is positive, the macro will go fine. You’re like Long and Plosser, King and Plosser in your macro. Is that wrong?

Research commentary

Adam asked: implicitly, via “Who?” and the request to explain the paragraph — see King and Plosser - Real Business Cycles

Habakkuk’s argument

Sir John Habakkuk, American and British Technology in the Nineteenth Century (1962) — Acemoglu links this exact edition in the transcript.

The puzzle: why did the United States, poorer and less industrially mature than Britain, adopt more mechanized production methods?

Habakkuk’s answer: abundant land made labor scarce. A worker could always go west and farm, which put a floor under wages. Expensive labor made machinery relatively cheap, so American manufacturers mechanized aggressively — interchangeable parts, the “American system of manufactures” — while British firms, with cheap abundant labor, had less reason to.

The general principle: the direction of technical change responds to relative factor prices. Technology isn’t an exogenous rain of ideas; it points wherever the expensive input is.

The lineage

An intellectual history · dates are not to scale

Scarcity changes what is worth inventing.

Follow one question through the literature: when labor becomes scarce or expensive, does innovation turn toward saving it?

01 The intuition and the early models

1932

Hicks · The Theory of Wages

Relative factor prices can influence the direction of invention.

1962

Habakkuk · American and British Technology

A historical argument: scarce American labor encouraged mechanization. The thesis remains contested.

1964–1966

Kennedy, Samuelson, Drandakis & Phelps

Formal models turn induced innovation from a historical intuition into an economic mechanism.

1969

Kamien & Schwartz

Further modeling of induced technical progress.

02 Directed technology and demographic change

1998–2002

Acemoglu · Directed technical change

Market size and relative prices help explain which technologies innovators develop.

2018–2022

Acemoglu & Restrepo · Demographics and Automation

From working paper to publication: aging is associated with more automation. Productivity effects depend on the setting.

2026

Acemoglu, Autor, Beirne & Scott · Baby Busts and Growth Booms

The paper Cowen invokes when asking whether fewer young workers can induce a technological response.

What to take away Incentives can redirect technology. They do not guarantee that every society will adapt, or that the benefits will be shared.

Sources & context: Acemoglu, Factor Prices and Technical Change: review of the earlier literature · Demographics and Automation · Baby Busts and Growth Booms

Acemoglu’s own line — “The models that I’ve been working on for the last 25 years on this topic always said that’s a possibility” — refers to his directed technical change work of the late 1990s and early 2000s, which supplied the market-size and price effects that make induced innovation work formally rather than as an intuition.

Why it matters for the fertility argument

If technology is exogenous, fewer young workers simply means less output and a shrinking economy — the demographic panic.

If technology is directed, scarcity of young workers raises their relative price, which pushes innovation toward labor-saving methods, which raises output per worker. The demographic shock partly answers itself.

That is precisely what Baby Busts and Growth Booms claims to find empirically: regions and countries with fewer young workers show more labor-saving patents, more high-tech activity, and higher TFP growth.

The caution Acemoglu himself puts on it

Twice, and both are important:

“it’s not a certainty, but it’s only after seeing the evidence that I’m more in that camp.”

and, on choice:

“In both papers, you also see the element of choice. You have to do the technology, and not every society does that technology in the same way. We could get that wrong.”

This is the load-bearing connection to the rest of his work. Induced innovation is a tendency, not a law. Automation that responds to genuine scarcity is good; the same automation deployed where labor is abundant is the displacement story of Automation and the Labor Share. Same mechanism, opposite welfare consequence, depending on conditions.

It is also why the Habakkuk framing is a better fit for him than the RBC framing Cowen offered. RBC says the economy self-corrects. Habakkuk-via-Acemoglu says the economy responds to incentives, and whether the response is good depends on what the incentives are — which leaves plenty of room for policy and for getting it wrong.

Reading

Working notes

Habakkuk’s thesis is contested and I should say so plainly: economic historians have pushed back for sixty years, notably on whether American labor really was that much scarcer once you account for skill mix, and on whether British firms were as unmechanized as the story requires. Peter Temin and others have argued the wage-gap evidence is weaker than Habakkuk claimed. Acemoglu calls it “intriguing,” which is doing some work. Draft 2 should give the counter-literature a proper paragraph rather than the sentence it has here.

Checked against the book: Habakkuk is not in it, and neither is the nineteenth-century labor-scarcity literature. The book’s version of “technology responds to conditions” is contemporary and institutional rather than historical — Chapter 6 on German versus American robot adoption, where the difference is union bargaining and apprenticeship rather than relative wages, and Chapter 9 on why business models and AGI ideology push AI toward automation. That is induced innovation with the inducement coming from institutions and beliefs instead of factor prices, which is a meaningfully different claim and arguably a more defensible one. Worth noting in draft 2 alongside the counter-literature: Acemoglu calls Habakkuk “intriguing” on air and builds on something else in print.

Checked against the audiobook edition (Penguin Random House Audio, narrated by John Lee), machine-transcribed; references are by chapter.

Related: King and Plosser - Real Business Cycles · The Lucas Critique · Acemoglu and Restrepo - The Task Framework · Automation and the Labor Share

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