What exactly is an epicycle supposed to translate into in a heliocentric theory?
You evaluate both theories in terms of predictive power, and then compare the two.
Ah, I see what you and Feyerabend are doing there: commensurability is supposed to allow some translation between the internal parts of the theories. I don’t see why that should be necessary, or why that would be called ‘commensurability’. Ordinarily, to say 2 things are commensurable merely requires that they are comparable by some common standard.
If you can reject it because it makes worse predictions, doesn’t that make the theories commensurable, regardless of how they relate to reality?
Not at all. What exactly is an epicycle supposed to translate into in a heliocentric theory?
You evaluate both theories in terms of predictive power, and then compare the two.
Ah, I see what you and Feyerabend are doing there: commensurability is supposed to allow some translation between the internal parts of the theories. I don’t see why that should be necessary, or why that would be called ‘commensurability’. Ordinarily, to say 2 things are commensurable merely requires that they are comparable by some common standard.