[brw12]

You're pointing to an important difference: between being uninformed but trying to get towards being informed, and being uninformed but fiercely protective of your certainty.

What Would Feynman Do?

In this case, I'm imagining he'd say these are some of the things we think might explain bodies' keeping or losing atmosphere, but we have to remember that almost everything we think we know about planets and moons comes from looking at the light that bounces off of them and making guesses about the underlying rules, but we still don't know do much about the underlying rules of physics, so there's probably more that we don't know than what we do know about atmosphere retention.