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Naively, (and endorsed by Aristotle) one expects heavier things to fall more quickly, Galileo Galilei showed in fact this is not correct, and that in fact how they fell as independent of mass (if air resistance remained negligible). Did he offer an explanation of this observation?

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Yes, but I take objection to calling Aristotle "naive". It was Galileo who was naive--- his naivete is what makes modern science successful, since we all are naive in the same way today. – Ron Maimon May 9 '12 at 23:23
I'm not calling Aristotle naive, but the hypothetical layman. I'm saying that Aristotle claimed that heavier objects fell more quickly than lighter ones. – Mozibur Ullah May 9 '12 at 23:41
I am saying that thousands of naive laymen probably knew Aristotle was full of crap for centuries, just by dropping heavy and light objects next to each other. Aristotle was a poweful influential moron, the naive laymen (this includes Galileo) are the ones who were right, then as now as always. The difference between Galileo and the others is that Galileo was willing to endure persecution to publish his findings in Italian. – Ron Maimon May 10 '12 at 1:12
This question is essentially a duplicate of this Philosophy.SE question, which is now migrated to Physics.SE as well. – Qmechanic♦ May 10 '12 at 9:51

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Yes--- he argued as follows in Dialogue concerning the Two Principal World Systems: suppose you tie a heavy object to a light one with a rope, would the light object fall slower and retard the heavy object, or would the heavy and light object together be a heavy object that falls more quickly? He concludes that neither: they both fall at the same rate.

This type of philosophical argument is persuasive, but Galileo always backs it up with naive experiments, and naive measurements. Aristotle's views are almost never "naive" in this way, and because of this they are almost never correct! Aristotle was writing for elites, and his pontifications are designed to be erudite and convincing, they are not designed to be correct, or else he would have done the experiment too. His books are ancient coffee-table books, they have no academic value.

Anyone who did the experiment would have seen Galileo is right, it is the non-naive arguments about the medium being the cause of the motion, and the impelling motive forces and desires of objects, that make Aristotle's blatherings both the opposite of naive, and the opposite of correct.

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Do you know whether any of the ancient atomists (greek, indian, islamic) made a similar argument? – Mozibur Ullah May 9 '12 at 23:52
But medium can be the cause of motion: isn't spacetime a medium & the cause of gravity? Of course it does depend on exactly what you mean by medium, early 20C physics dropped the idea of a mechanical medium for light for the field medium. As for the desires of objects, is it any better to call it a law of attaction? – Mozibur Ullah May 10 '12 at 0:20
@MoziburUllah: Nobody in ancient times that survives, but it's possible. I would have expected Archimedes to mention it if it existed, he doesn't. The medium is not the cause of motion, the field is not a "medium" in A's sense, objects don't have tendencies. None of his stuff has value, it is elitist garbage, please don't read modern things into it, it's unsalvagable. His argument for a medium was an argument against Democritus's atoms, and the argument that speed increases to infinity in vacuum, so nature fills all void with stuff ("Nature abhors a vacuum"). This was stupid garbage even then. – Ron Maimon May 10 '12 at 1:05
Well I see the Aristotelian argument as follows: all inertia is due to viscosity (he also argues that all free moving bodies will stop sometimes). This is wrong, but it makes sense and viscosity contributes to the speed of falling objects so that the more massive ones indeed fall faster than lighter ones if they have the same shape. – Anixx May 10 '12 at 5:01
@Anixx: This is a modern reinterpretation of Aristotle. What he actually says is that if you have an object, it's motion is intrinsically an interaction of object and medium, and happens faster as the medium is more tenuous. Not because of viscosity, but because it is pushing the medium out of the way! Note that in modern theories the "pushing of a fluid out of the way" does not create friction without internal viscosity, so that moving a ball in He4 at slow velocities is frictionless, even though you push He4 out of the way. Aristotle continues that if the medium is infinitely dilute... – Ron Maimon May 10 '12 at 5:11
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