Followup to: Archimedes's Chronophone.

Suppose you could send messages back in time to Archimedes of Syracuse, using a chronophone which - to avoid transmitting anachronistic information - transmits the results of executing cognitive strategies, rather than words. If you say "Women should have the vote", it comes out as "Install a tyrant of great personal virtue", because you repeated what your culture considers a wise form of political arrangement, and what comes out of the chronophone is the result of executing the same cognitive policy in Archimedes's era.

The chronophone won't transmit arguments you rationalize using your home culture's foreknowledge of the desired conclusion - it will substitute the result of executing that cognitive policy using Archimedes's culture's belief as the intended conclusion. A basic principle of the chronophone is that if you say something considered obvious in your home culture, it comes out as something considered obvious in Archimedes's culture.

The challenge was to say something useful under this restriction. This challenge is supposed to be difficult. It's really hard to get somewhere when you don't already know your destination. If there were some simple cognitive policy you could follow to spark moral and technological revolutions, without your home culture having advance knowledge of the destination, you could execute that cognitive policy today - which is what the whole parable is about!

A surprising number of respondents seemed to completely miss the point of the chronophone, just thinking up things they would like to say directly to Archimedes. The classic question of "If you went back in time, how would you start up an industrial civilization?" has been done many times in science fiction (Lord Kalvan of Otherwhen, The Cross-Time Engineer). There are thousands of things we'd like to say to the Past. The difficult part of the question is: How do you get it to come out of the chronophone?

Ger suggested teaching Archimedes decimal notation. Well, if you speak decimal notation - our home culture's standard representation of numbers - into the chronophone, then the chronophone outputs the standard representation of numbers used in Syracuse. To get a culturally nonobvious output, you need a culturally nonobvious input. Place notation is revolutionary because it makes it easier for ordinary people, not just trained accountants, to manipulate large numbers. Maybe an equivalent new idea in our own era would be Python, which makes it easier for novices to program computers - or a mathematician trying to standardize on category theory instead of set theory as a foundation for mathematics. Coming up with that chronophone input suggests that maybe we should pay more attention, in this era, to Python or category theory! A new representation that makes math easier can add up to a lot of benefit over time.

Hertzlinger remarked: "Some of Archimedes's most potentially-important research involved things he regarded as trivial toys. So if we advise him to get interested in Rubik's cube..." Of course you cannot directly describe a Rubik's Cube into the chronophone. So I asked what corresponding input Hertzlinger would say into the chronophone - has Hertzlinger followed the cognitive policy of playing with toy ideas? Maybe if this would have been such a good policy for Archimedes to follow, we should follow it ourselves.

Robin Hanson proposed an (admittedly clever) meta-trick for fine-tuning the chronophone's output. If that worked, Robin wanted to suggest trying to make useful devices that make money, and creating a tradition of this activity. I asked Robin if he'd ever tried to make such useful devices himself - if this is so important to human progress, why isn't Robin doing it? Perhaps Robin could reply that we've already gotten a huge amount of progress out of inventing gadgets, so now this no longer offers the greatest marginal returns. But that, in turn, points up one of the essential difficulties of the challenge. In this era it is culturally obvious - a non-surprising idea - that money-making new technologies benefit humanity. What could you say into the chronophone that would correspond to the nonobviousness of that idea in Archimedes's era? I don't know if it's important enough to qualify, but, for example, Robin's thoughts about prediction markets are not considered obvious in modern culture. That makes them a better bet for chronophone input than if Robin were to describe his efforts to invent a fancy new gadget. Everyone's doing that these days; it would probably come out of the chronophone as a suggestion to become a great warrior.

Richard Hamming used to ask his fellow researchers two questions: "What are the most important problems of your field?" and "Why aren't you working on them?"

What kind of ideas have provided the greatest benefit to humanity? Why aren't you thinking them?

Most of what we desperately want to say to Archimedes is not obvious relative to Archimedes's culture. This strongly suggests that the most important things the Future would want to say to us are, amazingly enough, not things that everyone already knows. If you want to really benefit humanity, you've got to do some original thinking - come up with the sort of nonobvious idea that you would speak into a chronophone. And you have to do some hard thinking about areas of application, directions of effort. You can't just run off in the direction of what your contemporary culture has instilled as the reflex answer to the question "How can I benefit humanity?" In those orchards the low-hanging fruit is gone.

The point of the chronophone dilemma is to make us think about what kind of cognitive policies are good to follow when you don't know your destination in advance. If you can just tell Archimedes to build a capitalist society because your culture already knows this is a good idea, it defeats the purpose of the dilemma. The chronophone transmits cognitive policies, not sentences. What sort of thinking are we doing now that is analogous to the kind of thinking we wish Archimedes had done then?