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Philip Trammell's avatar

> "Chad Jones calculates that, with an elasticity of 0.2, an infinite amount of what software does today would raise GDP by only about 2%, infinitely automating a third of GDP would raise it by 11%, and infinitely automating half of GDP would raise it by 19%."

Just flagging that this is under the extreme condition that the people who had been doing the automated fraction of GDP do not reallocate to the tasks that remain non-automated. At the other end of the spectrum, if they all reallocate immediately, automating half of GDP doubles GDP even if the elasticity of substitution is 0 (and raises GDP by 138% if the elasticity is 0.2). I don't doubt that if we really automated half of GDP, reallocation over the next say 5 years would be imperfect, but unless we have a strong case for thinking there would be next to none, the level effect should be somewhere well into the middle of the 19%--138% range, no?

As for how fast we should expect the reallocation to happen, to my mind the natural question is not how much we should expect AI to facilitate reallocation *relative to past reallocations*, but how fast we should expect AI to facilitate reallocation *relative to the speed at which it facilitates automation*. E.g. if we think that doubling GDP via automating ~half of it has historically taken 35 years (1.02^35=2), and that reallocating workers to the remaining half has also historically taken 35 years, then if we're imagining a scenario in which AI automates half of GDP in 5 years, do we think that the reallocation will take more or less than 5 years? Reallocation is itself an economic activity composed of tasks that can be automated or augmented with the right AI and equipment, and in principle it could be accelerated in an extreme way, e.g. with smart glasses whispering instructions into our ears about what to do with our hands in our first day on the job as a chef or construction worker.

I'm not saying the reallocation will necessarily happen as fast as the automation--I expect it will happen more quickly in some industries and more slowly in others, and that the ones in which it happens more slowly will grow in their shares of GDP and pull the growth rate down--but focusing on the zero-reallocation case seems misguided to me.

Tom C's avatar

A few quick questions:

1. It seems to me the biggest difference between your baseline model and the people you cite is that you assume full automation will take 20 years, while they assume shorter? Is that fair?

2. I'm not sure your assumption on elasticity of substitution: you state σ=0.2, but your graph shows computer hardware which illustrates σ≈1 (i.e. it's a sector where price collapsed but spending changed relatively little). How to reconcile this?

3. The demand argument I found a bit hard to follow: if it's about lower MPC, then wouldn't that increase savings and so accelerate growth? Or is this a Keynesian norminal story, so should I expect this to be a transitional/short-run effect?

4. The argument seems to flip between output growth and measured output growth. The title says "growth" and the opening asks "how much richer will you be?" But then halfway through you seem to say that your forecasts don't necessary apply to growth or to welfare but rather to *measured* growth ("4-5% measured growth could go along with (potentially very large) welfare gains.") If you think there's a significant wedge between the economically-relevant quantity, and the measured proxy, and some of your arguments apply only to the latter, then it seems worth flagging that in the title of the piece.

5. You seem skeptical of AI's effect on R&D, Ben's tweet says "There is no evidence for it so far." This surprises me -- how do you interpret the 2026 data on discovery of cyber vulnerabilities, resolution of open math problems, and optimization of algorithms?

6. You talk about the blindspots of technologists, I wonder what you would say your own blindspots are? Your tweet talks as if 4-5% annual growth is a reasonable forecast. I'm pretty sure when we talked in London last year you weren't expecting 4-5% growth, what changed? Do you think your opinions will change again?

Notable that Acemoglu was expecting 0.06% incremental growth in 2024, and was endorsed by many people. Your forecast is 50X higher, and Acemoglu seems to have disavowed his earlier analysis. Also notable that the Jones-Tonetti paper forecasts changed dramatically between late 2025 and early 2026, the first version predicted neglible growth impact for decades, the second version multiple percentage points.

There seems to be a very strong pattern of economists revising their forecasts up by more than a factor of 10. How do you account for this?

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