But how can someone be trustworthey without intelligence? Even if they want to do what's best, they can't be relied to do what's best if they can't figure out what the best thing to do is. Generally speaking, the more intelligent someone is, the more predictable they are (there are a few exceptions, such s where a mixed strategy is optimal). The fact is that idiots can often screw things up more than selfish people. With a selfish person, all you have to worry about is "Is it in their interests to do what I want?" And if you're not worrying about that to begin with, then perhaps you are being selfish.
Intelligence is clearly correlated with expected value, and it's definitely better than nothing at all. Furthermore, smart people are better than stupid people at convincing you that they're smart. But honest people are often worse than dishonest people at convincing people that they're honest.
A lot of this seems extremely contrary to my intuitions.
Poor performance (for instance on tests) isn't the result of having a high rate of random errors, but of exhibiting repeatable bugs. This means that people with worse performance will be more predictable, not less — in order to predict the better performance, you have to actually look at the universe more, whereas to predict the worse performance you only have to look at the agent's move history.
(For that matter, we can expect this from Bayes: if you're learning poorly from your environment, you're no...
If you believe that science is about describing things mathematically, you can fall into a strange sort of trap where you come up with some numerical quantity, discover interesting facts about it, use it to analyze real-world situations - but never actually get around to measuring it. I call such things "theoretical quantities" or "fake numbers", as opposed to "measurable quantities" or "true numbers".
An example of a "true number" is mass. We can measure the mass of a person or a car, and we use these values in engineering all the time. An example of a "fake number" is utility. I've never seen a concrete utility value used anywhere, though I always hear about nice mathematical laws that it must obey.
The difference is not just about units of measurement. In economics you can see fake numbers happily coexisting with true numbers using the same units. Price is a true number measured in dollars, and you see concrete values and graphs everywhere. "Consumer surplus" is also measured in dollars, but good luck calculating the consumer surplus of a single cheeseburger, never mind drawing a graph of aggregate consumer surplus for the US! If you ask five economists to calculate it, you'll get five different indirect estimates, and it's not obvious that there's a true number to be measured in the first place.
Another example of a fake number is "complexity" or "maintainability" in software engineering. Sure, people have proposed different methods of measuring it. But if they were measuring a true number, I'd expect them to agree to the 3rd decimal place, which they don't :-) The existence of multiple measuring methods that give the same result is one of the differences between a true number and a fake one. Another sign is what happens when two of these methods disagree: do people say that they're both equally valid, or do they insist that one must be wrong and try to find the error?
It's certainly possible to improve something without measuring it. You can learn to play the piano pretty well without quantifying your progress. But we should probably try harder to find measurable components of "intelligence", "rationality", "productivity" and other such things, because we'd be better at improving them if we had true numbers in our hands.