Since materialists had to believe that human intelligence resulted from the operation of mechanical systems located in the human body . . .
What little I know about ancient Greek thought makes me doubt that they would have been equipped to follow up on the full implications of "materialism" in the modern sense. Following Newton, we're now all completely accustomed to the idea that everything on Earth is governed by the same basic principles as everything else in the universe. We're used to the idea of matter and energy and forces being quantified into precise algebraic formulas, and even random events can be described with some precision. But the Greeks, for all their knowledge of geometry, did not know algebra or probability.
As I understand it, the prevailing view in those days was that the things above the moon -- the stars and planets -- followed mathematical patterns (moving in circles, of course, because circles are so obviously terrific). However, on Earth, in our imperfect sublunary sphere, things had tendencies and impulses. Fire more or less wanted to go up, and water down, more or less in the same way that a squirrel wants to run away from a dog.
According to Wikipedia :
Aristotle also argues that the mind (only the agent intellect) is immaterial, able to exist without the body, and immortal. ...One argument for its immaterial existence runs like this: if the mind were material, then it would have to possess a corresponding thinking-organ. And since all the senses have their corresponding sense-organs, thinking would then be like sensing. But sensing can never be false, and therefore thinking could never be false. And this is of course untrue. Therefore, Aristotle concludes, the mind is immaterial.
Why did he believe sensing could never be false? Surely he must have known about say mirages or camouflage.
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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