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Robert Waldmann's avatar

Oh my oh my the exponential error is old. Malthus said population would outstrip production because it grew exponentially. In fact, since about then, output has grown exponentially (except for world wars, depressions, and growth miracles).

But the more important point is that the exponent in population can be zero*t . It can also be lower as it is here in Italy. Exponential can be constant or shrinking.

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Robert Waldmann's avatar

I am actually sincerely disappointed that the genuinely brilliant Cosmos Shalizi misused the word “exponential” to mean “very rapid”. 1% per billion years is exponential. Real GDP increasing by 1000000000000000000 a second is linear.

The idea that exponential means faster is the idea that T has gone to infinity. Asymptotically we will all be dead.

Also exponential growth is highly predictable. One of the gross errors of macroeconomists (noted just as I arrived) was assuming that macro variables were stationary around an exponential trend.

This was partly due to Anglophone hegemony no pre- eminence no, oh hell, there must be an Anglo Saxon word for it. The US, Australia, Canada, New Zealand, and the UK are the only OECD countries with merely exponential growth. The others all had exponential usually and also a growth miracle with higher than ordinary growth rates.

I would have hoped that de expert on DeLong run would have noted this. There has never been an exponential revolution - it is roughly a contradiction in terms.

Also T is not infinity yet and another (appropriately) persistent error of macro is assuming it is

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