This makes testable, measurable predictions about "why things fall down", i.e. "things fall down because all things obey the law of universal gravitation as given in the formula...". But it doesn't even begin to explain why there is gravity all rather than no gravity. Science is largely silent about this category of question of meaning not measurement - it observes reality and predicts based on extrapolating from existing observations. Other explanations of "why"
are hardly much better - "gravity exists because God said so" aren't very satisfying since you can't test it or infer anything from it.
"Things always fall down" doesn't add much. It says that the observation can be repeated.
Newton's law says more than "There exists gravitational force between bodies" which isn't much of an improvement over "things always fall down".
Newton provided a mathematical formula to measure it, which, as best as could be seen in Newton's time, fit exactly with reality, applying from apples up to planets. http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gra...
This makes testable, measurable predictions about "why things fall down", i.e. "things fall down because all things obey the law of universal gravitation as given in the formula...". But it doesn't even begin to explain why there is gravity all rather than no gravity. Science is largely silent about this category of question of meaning not measurement - it observes reality and predicts based on extrapolating from existing observations. Other explanations of "why" are hardly much better - "gravity exists because God said so" aren't very satisfying since you can't test it or infer anything from it.