That implies that the competing theoretical frameworks overlap, right? — Srap Tasmaner
I'm not sure what you mean by that.
What I mean is that, assuming some common background theory, an observation might imply that such-and-such is the case. But of course we could always instead change the background theory so that the observation does
not imply that such-and-such is the case. As Quine points out, we're always testing the combination of whatever thing we're explicitly trying to test with an observation, plus all of the background theory that's we're not explicitly trying to test. And that's a totally unsurprising thing to me; of course we're always testing the combination of all of our beliefs.
Like, a medieval astronomer noting the retrograde motion of planets could conclude from that observation that the true motion of planets cannot be simple circles, and that we must conclude that they follow epicycles around intermediary points that in turn circle the Earth as we previously supposed the planets to.
Or, Copernicus might point out to them, we could instead modify our background assumption that planets circle the Earth at all, and instead suppose they and the Earth circle the sun, and the relative motion of the Earth and (other) planets would account for the observation of retrograde motion in the sky.
Except, that still doesn't perfectly fit the observations, so the critics might retort that we do in fact need to conclude that epicycles are real anyway, whether or not the planets circle the sun.
Unless, Kepler might point out to them all, we instead modify out background assumption that everything in the sky moves in
circles at all, and allow for the possibility that their motion is elliptical.
So the observation of retrograde motion either proves that epicycles are real, or else disproves the assumption that planets move in circles*. Either way, we're still adapting our theory to account for the observations, and so still doing empiricism.
*(Or... any of an infinite number of other possible explanations that would still fit that observation).