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I always thought that science is something we model out of the real world. That is, we basically observe a few things and then we come up with a model to explain the observations and predict more.

In this backdrop, Newton observed attraction between bodies with mass. He called it gravity. Now gravity was his model of how things with masses should behave among each other. Does this gravity actually cause things to fall to the ground? Wasn't it a model to explain attraction in the first place? Does it have to "cause" this attraction?

Just to be clear, I am not asking for clarification of Newton's law of gravity. I am using it as an example for any general model in physics that we have that explains natural phenomenon - does it cause the phenomenon actually?

  • Newton explicit point of view is subtle: he proves that - according to his laws of motion - there must be a force causing the "change of motion": accelating it from rest for a falling body or "bending" its linear tarjectory for a planet orbiting the sun. He call this force: gravity. That's the gist of N's masterpiece: the Pricipia. – Mauro ALLEGRANZA Jun 28 '16 at 12:22
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    N's theory left open a (big) problem: how this force acts ? By contact (this was the only allowed mechanism for Descartes) or at distance (like magnetical attraction) ? If gravity acts at distance, how it is transmitetd ? what medium it is needed to "transfer" it ? Newton "speculated" about this, but his "official" position was the well known: hypotheses non fingo: "I have not as yet been able to deduce from phenomena the reason for these properties of gravity, and I do not feign hypotheses." – Mauro ALLEGRANZA Jun 28 '16 at 12:26
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    To be consulted: Andrew Janiak, Newton as Philosopher (2010), Andrew Janiak & Eric Schliesser (editors), Interpreting Newton: Critical Essays (2012) as well as: Newton: Philosophical Writings, A.Janiak editor (2014). – Mauro ALLEGRANZA Jun 28 '16 at 12:44
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    And my answer still remains the same: YES. Newtonian explanation of falling bodies and planets revolution due to the attractive force of gravity is the model of causal explanation that has been followed by scientists till today. – Mauro ALLEGRANZA Jun 28 '16 at 13:01
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    Regarding your particular example, Newton's theory of gravity is a descriptive theory. It does not attempt to explain why objects fall, but rather how. Einstein takes that a step farther, and states that the presence of massive objects bends space-time and bent space-time causes objects to fall. That gives one step toward the answer why. The next question is, why do massive objects bend space-time. To your more general point, science is a social process of creating descriptive, predictive models of physical phenomena. As Boxer said, "all models are wrong, but some are useful." – John Yetter Jul 1 '16 at 15:11
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I believe that you are getting confused between applying the same word, e.g. gravity, to both our understand/description of what is going on and to the actual physical phenomenon. Sometimes explicit language is used to differentiate these cases.

Sometimes you might hear "the law of gravitation" or "theory of gravity" or similar to refer to the scientific ideas and mathematical description of the phenomenon.

Sometimes you might hear terms like "the phenomenon of gravity" or "the physical effects of gravity" or similar which call out that the speaker is referring the physical phenomenon. This is how we can refer to the natural phenomenon itself.

I'm sure that there are instances where a bare term, i.e. just "gravity", is used to refer to the phenomenon itself, and there are other instances, involving a different context, where it is used to refer to the conceptual understanding. It is up the the audience to infer exactly what is meant. In mentally reviewing the use of the term "gravity" without qualifiers like "theory of" or "law of" or "equations for", I can't think of an instance where it means anything other than the physical phenomenon. I've always heard Newton's result referred to as "the universal law of gravitation", not just bare "gravity". I see the same pattern in "evolution" (refers to the physical phenomenon) and the "theory of evolution" (refers to the conceptual picture). So I suspect that the default, in the absence of any qualifiers, is that the bare terms tend to (but not necessarily always) refer to the physical phenomenon.

  • I get it, thanks, embarrassing to make such a mistake really, but I was coming off from another argument which led to this and could not really clarify. – user12196 Jun 28 '16 at 14:36
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\The notion of cause is problematic. It was raised first in Aristotle who noted one can only say certain acts coincide, and it was later raised by Hume in essentially the same form.

In physics there is a certain notion of 'pragmatic cause' by which one can say that gravity 'causes' a stone to fall; or the earth to revolve around the sun.

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