[0. A long history of theoretical and experimental discoveries lead to a specific, well-motivated theory (General Relativity) describing gravitational phenomena

[0. A long history of theoretical and experimental discoveries lead to a specific, well-motivated theory (General Relativity) describing gravitational phenomena.] 1. Theory predicts a very specific and recognizable class of gravitational wave patterns for likely sources, whose details are determined by a small number of parameters that correspond to meaningful physical quantities (specifically, two masses and a distance; I don't know if there are any more than that). 2. Two independent experimental instruments measure a wave pattern that (apart from some low-level noise) is an excellent match to one of the predictions. Fitting the model to match the specific data, the resulting parameters have entirely plausible astrophysical values. 3. This is considered an example of a theory making a specific, novel prediction that is later confirmed by experiment: pretty close to the classic definition of the scientific method. 4. Therefore, the experimental data has provided strong support for the premises of the theory being tested: both its prediction of gravitational waves and its detailed dynamical predictions for the source scenario matching the observations. Maybe I'm misunderstanding something in your argument, but I don't see any circularity here. What about this process isn't precisely the way that science is supposed to work?