Galileo's argument is actually quite slipshod and is based on the ambiguity of language and the narrowness of what-we-commonly-experience as a slice of all-that-really-is.<p>If Aristotle were right then the rocks would EITHER fall slower or faster together. There is no "knowing" if they are one object or two.<p>But Aristotle is wrong. Which means Galileo's thought experiment is irrelevant to reality and should be ignored. The picture is very simple: gravity pulls down, air resistance pushes up. Gravity is constant but air resistance is higher for faster moving objects. That's all you need.