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#5530·Dennis HackethalOP, about 20 hours agoSome variations are good (and then described as reach). I could vary the axis-tilt explanation of the seasons by replacing earth with any other tilted planet (as I did in #5526). I could do this infinitely many times, including for yet-to-be-discovered planets and even imaginary ones. But that doesn’t make the explanation worse. (That isn’t your fault, I think Deutsch just hasn’t gotten technical enough about the difference between reach vs. easy to vary.)
I think this is where the problem/question given to the program matters.
If the problem I'm trying to answer is “Why does Earth have seasons?”, then replacing Earth with Mars doesn't give me another working variation of the explanation of Earth's seasons. I've changed the phenomenon I'm trying to explain. Applying the same underlying theory to explain seasons on Mars seems to me like an example of its reach, not a variation of its explanation of Earth's seasons.
This is one reason the program asks for the question first. Whether a proposed variation still works can't be judged independently of what we're trying to explain.
As I explained in #5553, the program relies on the user's understanding of both the problem situation and the explanation. So I agree that reach and easy-to-vary shouldn't be confused, but I don't think the program requires us to confuse them. The user has to judge whether they've varied an explanation while preserving what it was supposed to explain, or instead applied the explanation to a different problem.
And of course people can disagree about that distinction, because they can understand the problem situation and explanatory argument differently. That's part of the human judgment the program deliberately leaves to the user.