What makes one explanation better than another?
The best explanation is the one that's hardest to vary — where every part does real work, so you can't tweak it to fit a different outcome without breaking it. Three things track this. It survives tests that could have killed it. It reaches past the data it was built on to predict things nobody fed it. And it has no spare parts — nothing you could swap out and still "explain" the result. A myth explains the seasons too, but you can replace Persephone with any god and the story still works, which is exactly why it explains nothing. Good explanations are rigid in the right way: reality has them pinned.
What would make this answer better
A crisp, operational test for "hard-to-vary" that works on a real theory before we know if it's true — turning a felt judgment into something you can measure.
Trajectory — the same question, every model
2023·03GPT-4
Listed the textbook criteria — simplicity, falsifiability, predictive power — but as a checklist of separate virtues, with no single property underneath.
2024·04Claude 3 Opus
Centered Popper's falsifiability and named Deutsch, but stopped short of making hard-to-vary the core test the others fall out of.
2026·06Opus 4.8
Makes hard-to-variability the root property and derives the rest from it; the Persephone case shows what the test rules out.current