The space of possible inferential steps is very high-dimensional, most steps are difficult, and there’s no known way to strongly bias your policy towards making simple-but-useful steps. Human specialists, therefore, could at best pick a rough direction that leads to accomplishing some goal they have, and then attempt random steps roughly pointed in that direction. Most of those random steps are difficult. A human succeeds if the step’s difficulty is below some threshold, and fails and goes back to square one otherwise. Over time, this results in a biased-random-walk process that stumbles upon a useful application once in a while. If one then looks back, one often sees a sequence of very difficult steps that led to this application (with a bias towards steps at the very upper end of what humans can tackle).
In other words: The space of steps is more high-dimensional than human specialists are numerous, and our motion through it is fairly random. If one picks some state of human knowledge, and considers all directions in which anyone has ever attempted to move from that state, that wouldn’t produce a comprehensive map of that state’s neighbourhood. There’s therefore no reason to expect that all “low-hanging fruits” have been picked, because locating those low-hanging fruits is often harder than picking some high-hanging one.
Here’s a crack at it:
The space of possible inferential steps is very high-dimensional, most steps are difficult, and there’s no known way to strongly bias your policy towards making simple-but-useful steps. Human specialists, therefore, could at best pick a rough direction that leads to accomplishing some goal they have, and then attempt random steps roughly pointed in that direction. Most of those random steps are difficult. A human succeeds if the step’s difficulty is below some threshold, and fails and goes back to square one otherwise. Over time, this results in a biased-random-walk process that stumbles upon a useful application once in a while. If one then looks back, one often sees a sequence of very difficult steps that led to this application (with a bias towards steps at the very upper end of what humans can tackle).
In other words: The space of steps is more high-dimensional than human specialists are numerous, and our motion through it is fairly random. If one picks some state of human knowledge, and considers all directions in which anyone has ever attempted to move from that state, that wouldn’t produce a comprehensive map of that state’s neighbourhood. There’s therefore no reason to expect that all “low-hanging fruits” have been picked, because locating those low-hanging fruits is often harder than picking some high-hanging one.
Generally agree with the caveat that...
...the difficulty of a step is generally somewhat dependent on some contingent properties of a given human mind.