[thethirdone]

You can't possibly know what will match experimental results in the future so that doesn't help determine good theories in the present.

And I would say that Newtonian gravity was a useful theory despite not matching experimental currently because when it was the best it mostly explained observations.

[chii]

> Newtonian gravity was a useful theory despite not matching experiment

"Useful" in this context means useful for a future theory or experimentation, not utility. Newtonian theory certainly predicted many results, and all of them were useful in the above sense. A prediction doesn't have to exactly match observations to be useful, but that the theory produces a prediction which _could_ be tested against.

Even flat-earth theory makes useful predictions - albeit already proven false as time and time again, it predicts the wrong results.

What isn't useful is an unfalsifiable theory, which means the predictions it makes is not able to be tested, or the results of such a test could be construed to match if you squint a bit. A theory like creationism, for example.

[thethirdone]

I am a bit confused by your comment. I'm not sure if you agree with gliop or not. I am simply saying that Newtonian gravity is useful (in pretty much any sense) and that it did not match all experiments. Particularly in the orbit of Mercury could not be explained.

> Even flat-earth theory makes useful predictions - albeit already proven false as time and time again, it predicts the wrong results.

I definitely agree usefulness is independent of fitting experimental data. gliop would seem to say flat earth theories are not useful.

[noego]

I don't think the value of a theory can be evaluated in isolation. It can only be evaluated relative to its competition. During its time, Newtonian gravity, even if it didn't perfectly fit all data, was still superior to its competition on an aggregate of the 3 criteria mentioned. Only once Einstein's theories were put forward, were we able to replace Newtonian gravity with a superior alternative.