369. The Harder They Fall: Galileo and the Renaissance

Posted on 28 March 2021

Did Galileo’s scientific discoveries grow out of the culture of the Italian Renaissance?

Further Reading

• I.E. Drabkin and S. Drake (trans.), Galileo Galilei, On Motion and On Mechanics (Madison: 1960).

• M.A. Finocchiaro (trans.), The Essential Galileo (Indianapolis: 2008).


R.E. Butts and J.C. Pitt (eds), New Perspectives on Galileo (Dordrecht: 1978).

• S. Drake, Galileo at Work: His Scientific Biography (Chicago: 1978).

• H. Gatti, “Giordano Bruno’s Ash Wednesday Supper and Galileo’s Dialogue of the Two Major Systems,” Bruniana e Campanelliana 3 (1997), 283-300.

• N. Jardine, “Galileo’s Road to Truth and the Demonstrative Regress,” Studies in the History and Philosophy of Science 7 (1976), 277-318.

P. Machamer (ed.), The Cambridge Companion to Galileo (Cambridge: 1998).

• P. Palmieri, A History of Galileo’s Inclined Plane Experiment and its Philosophical Implications (Lewiston: 2011).

• C.B. Schmitt, “Experience and Experiment: A Comparison of Zabarella’s View with Galileo’s De Motu,” Studies in the Renaissance 16 (1969), 80-138.

W.A. Wallace, Prelude to Galileo: Essays on Medieval and Sixteenth-Century Sources of Galileo’s Thought (Dordrecht: 1981).

• W.A. Wallace (ed.), Reinterpreting Galileo (Washington D.C.: 1986).

• W.A. Wallace, Galileo’s Logic of Discovery and Proof: the Background, Content, and Use of His Appropriated Treatises on Aristotle’s Posterior Analytics (Dordrecht: 1992).


Dom Paschal R Scotti 28 March 2021

 A great episode, especially as compression is so difficult. I would like to hear more about the trial(s) and perhaps we will later as you will be talking about the Catholic Reformation. Galileo did grow out of the culture of the Renaissance, and while there was much that was Aristotelian (esp. through the Roman Jesuits) there were were many elements, Platonic and other (he seemed rather eclectic), which others have referred to. You do a difficult thing and you deserve all the praise that people give you.    

Eric 28 March 2021

Hi Peter,

It's not very consequential to the episode as a whole, but I just wanted to correct your statement about the law of falling bodies that Galileo discovered. You said that the speed was proportional to the square of the time. But actually, it's the total change in position that's proportional to the square of the time. The speed is directly proportional to the time and the acceleration--the rate of change of speed--is constant.

Alexander Johnson 30 March 2021

I'm a bit confused on the scripture part.  

A:  I thought scripture needing to be in agreement with current scientific understanding was a central part of Augustine's statements on how the bible should be interpreted.  Am I mistaken?  Did this fall out of Fashion?

B:  I heard that Galileo spent a lot of time writing about the "correct" reading of scripture.  In the example given, he said God did stop the sun, he stopped the sun spinning, and everything in the universe only is in motion because the sun is rotating (including earth's rotating on its axis, as well as its revolving around its equant, and the equant revolving around the sun).  Is this mistaken as well?

On point A, Augustine's theory of scriptural exegesis is of course very complicated. I don't think compatibility between exegesis and natural science is a prime concern for him, he is much more interested in things like the centrality of the value of caritas in our interpretations. I certainly don't think he would go so far as Galileo (or Averroes) by suggesting that the natural scientist can just dictate to the theologian what the acceptable interpretations are, but he and most medieval thinkers would surely at least agree that natural science, when done well, is not going to disagree with the correct exegesis since both will be true.  I think the issue is more one of who has the authoritative position, and of course in Augustine's environment there was no one remotely like Galileo!

On point B Galileo's discussion of these topics is indeed extensive but also rather dialectical, that is, he is trying to refute the churchmen who tried to use the Bible to disprove Copernicanism. In the case you mention, he basically just says "well if God really stopped the sun, that would be easier to explain in my system than yours."

Jürgen Wüllrich 18 September 2021

The speed of spherical or cylindrical bodies that accelerate downhill is not easily predictable also for a reason other than friction of the surface and the air: The moment of rotational inertia. The potential energy of body that starts to roll down a slope is transformed into two "flavours" of motion energy, the sum of which cannot be bigger than the original potential energy: One is connected to the translatorial speed (the downhill speed) plus the other one connected to the rotational speed of the ball or cylinder. The heavier a body, the more moment of inertia it has. This is why a heavy ball rolls down a hill slower than a light ball (all other circumstances being equal) - and this is also why a bicycle is quite stable when moving but shaky when very slow. The moment of inertia does also depend on the inner structure of the sphere or cylinder, whether it is massive or hollow and so on. The Wikipedia article "Moment of inertia" has a few nice illustrations about this. 

Mark Victor 20 December 2021

New here to Philosophy (came by way of interest in Greek Mathematics), and starting with your book Classical Philosophy (exceptionally well written).

I'm wondering if you will eventually be able to say something about Philosophy of Science. The sources I have found so far (all introductory) pose such questions as: how can we be confident that Reality actually exists, or that it is governed by laws ? While these are questions that I suppose ought (initially) to be asked, apparently Philosophers of Science do not attempt to go beyond this; thus it is no accident that a course in Philosophy of Science is not part of a Physics Major; there is nothing to be learned there. Instead, Physics is taught by example, to some extent by giving historical examples, and partly by just letting students figure out for themselves how to do Physics (trial and error). Yet this approach either just gives up, or else tacitly assumes that an actually useful Philosophy of Science - in terms of being helpful at arriving at scientific knowledge - simply isn't possible, an interesting conclusion to say the least.

(Philosophy has nothing to do with Reality?)

Actually there has been quite a lot of philosophy of science already in the series. Many episodes are on actual scientific topics (see under the relevant theme) and we have had not only Aristotle's theory of science in the Posterior Analytics but also lots of reactions to it, including most recently the episode on Zabarella in the Renaissance series.

In general I would say that scientists actually used to be more conscious of their philosophical and methodological presuppositions than they are now; this ceased being the case when philosophy and the empirical sciences started to drift apart but this is really only a phenomenon of the last couple of centuries.

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