> if I asked a human cryptographer "why is there an XOR in this round?" I'm asking about the fourth one, the final cause or purpose; the cryptographer might answer "because I wanted uncorrelated input bits to stay uncorrelated after this round", or whatever. But talking about that most interesting "why?" as regards an AI's activity is... controversial, to say the least.
Really? We don't seem to have any problems with saying "your eyeball contains a lens to focus light onto the retina" or "predators have sharp teeth because that is the efficient way to handle meat, as opposed to fibrous plants", but those are both final causes. There's nothing different about an AI's activity. Any activity or quality that is pursuant to a goal, however defined, may have a final cause.
Evolutionary biologists are perfectly comfortable with the idea that focusing light is the purpose of a lens, and cutting meat is the purpose of sharp teeth, and structural support is the purpose of a skeletal system, etc. etc. etc. It's not fallacious in any sense. What they rant against is the idea that items with a purpose must have been ordained by a supernatural force.
No, answering a why question about an organism's structure with "because [purpose]" really does get a evolutionary biologist's goat.
Why do tigers have sharp teeth? To rip flesh.
No.
Why do tigers have sharp teeth? Because their ancestors who had sharper teeth produced more offspring than their relatives who did not.
In Aristotle's language, ripping teeth may be a cause, but it's not the Final cause, and that's what we're talking about.
The reason biologists don't like the teleological explanation is that (a) it tends to make people think of a creator, as you say, but also (b) it describes traits as "solutions" to specific "problems" (e.g. the problem of ripping flesh), but the issue is that, starting from the pre-sharp-toothed ancestor, there were infinitely many possible directions evolution could have taken that would never have needed to solve this "problem." The existence of the problem (cutting meat) and the random path that led to the tigers being carnivorous are actually one-and-the-same. If you didn't have sharp teeth, you wouldn't have needed them.
Really? We don't seem to have any problems with saying "your eyeball contains a lens to focus light onto the retina" or "predators have sharp teeth because that is the efficient way to handle meat, as opposed to fibrous plants", but those are both final causes. There's nothing different about an AI's activity. Any activity or quality that is pursuant to a goal, however defined, may have a final cause.