On Thursday Matt Ridley presented his new book The Rational Optimist at CATO, and I commented (vid available).  Here’s roughly what I said:

The formula for a successful popular non-fiction book these days is a sandwich: meat between bread slices. The bread is a general thesis that can be explained in a paragraph, with both a normative part to let readers take sides, and a positive part to let readers display sophistication. The meat is 400 pages of entertaining and vaguely-related but mostly unnecessary detail. Most readers would be overwhelmed if all this material were actually required to understand the thesis, but would also be insulted by a 40 page book.

Ridley achieves this formula well, and his meat is unusually dense and informative; I learned lots. But since reviews are supposed to focus on the bread, so let’s go there.

Ridley’s positive thesis is that specialization and trade among non-relatives was the key driver of innovation that let humans advance far beyond other animals. We have good evidence of trade over 100 mile distances about 80,000 years ago, and it may go back much further.  I completely agree with Matt here; trade was a key. And since people tend to think that whatever made humans unique must be great, since we humans are of course great, this should lead folks to think trade is great.

Ridley attributes the farming and industry growth speedups to humans recruiting more living species via domestication, and then recruiting dead species via fossil fuels.  I instead attribute those speedups to percolation transitions that increased network scales, first for trade and then for expert talk.

Ridley’s normative thesis is optimism, that things have long been getting better, and this will long continue. While I mostly agree, Ridley overstates his case. For example:

Knowledge … is genuinely limitless. There is not even a theoretical possibility of exhausting the supply of ideas, discoveries, and inventions. This is the biggest cause of all for my optimism. … The combinatorial vastness of the universe of possible ideas dwarfs the puny universe of physical things. (p.276)

Well possibilities may be inexhaustible, but their value is not. Within a million years we’ll find pretty much all combos that give value to creatures like us, and for trillions of years thereafter they’ll be little net gain.  Balking at paying large costs to avoid small risks of climate change catastrophe, Ridley says:

The trouble with this reasoning is that it applies to all risks, not just climate change …. Why are we not spending large sums stockpiling food caches in cities so that people can survive the risks from North Korean missiles, rogue robots, alien invaders, nuclear war, pandemics, super-volcanos? (p. 333)

But we should spend such sums. Just as we get more careful with our kids as we live longer, the more optimistic we are about our long term future, the more we should spend now to safeguard it.

Ridley is also too tempted to conflate optimism about the total power of our civilization with about optimism about individual quality of life.   While he accepts that totalitarian governments have at times reduced quality of life, and may do so again, he doesn’t directly acknowledge that farming reduced life quality, via wars, slavery, nutrition constraints, etc. And I envision that, within a century or so, new em tech will allow far more rapid population growth, reducing per capita wealth.

Overall though, Ridley is right: optimism is rational, even if uncool.