When I was a kid, my parents, especially my dad, used to talk about difficulties he had in raising me, and how they were related to difficulties that he had as a kid with his parents.
And I thought "that means I'll get to grow up better than my dad. And when I grow up and have kids, I'll have an advantage, and my kids will be able to grow up better off than me. And eventually my children's children's children will be rad as all get-out."
And while I hadn't really noticed until now, that was my point of reference for "intelligence explosion." It now seems clear to me that (a) most people haven't even begun to advance along this line, and/or see it as having some bounded destination, and (b) other types of changes will blow these out of the water, in the way that memetic evolution in humans blew genetic evolution out of the water. And honestly, that's scary. Because the improved-parenting intelligence improvement comes with a responsibility and morality improvement as well, built right in. Because it's a people-improvement, rather than mind-improvement.
But this type of intelligence increase, not really an explosion, seems pretty Greek-accessible to me, in the same way that "Science must pass Judaism" was accessible to Eliezer as a kid.
You correctly claim this inference to be Greek-accessible, while not an explosion, because it is explicitly mentioned in Plato's "The Republic" - although the measurement of good bringing up is defined as morality, not intelligence.
Also see: History of the Friendly AI concept.
The ancient atomists reasoned their way from first principles to materialism and atomic theory before Socrates began his life's work of making people look stupid in the marketplace of Athens. Why didn't they discover natural selection, too? After all, natural selection follows necessarily from heritability, variation, and selection, and the Greeks had plenty of evidence for all three pieces. Natural selection is obvious once you understand it, but it took us a long time to discover it.
I get the same vibe from intelligence explosion. The hypothesis wasn't stated clearly until 1965, but in hindsight it seems obvious. (Michael Vassar once told me that once he became a physicalist he said "Oh! Intelligence explosion!" Except of course he didn't know the term "intelligence explosion." And he was probably exaggerating.)
Intelligence explosion follows from physicalism and scientific progress and not much else. Since materialists had to believe that human intelligence resulted from the operation of mechanical systems located in the human body, they could have realized that scientists would eventually come to understand these systems so long as scientific progress continued. (Herophilos and Erasistratus were already mapping which nerves and veins did what back in the 4th century B.C.)
And once human intelligence is understood, it can be improved upon, and this improvement in intelligence can be used to improve intelligence even further. And the ancient Greeks certainly had good evidence that there was plenty of room above us when it came to intelligence.
The major hang-up for predicting intelligence explosion may have been the the inability to imagine that this intelligence-engineering could leave the limitations of the human skull and move to a speedier, more dependable and scalable substrate. And that's why Good's paper had to wait until the age of the computer.
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