I do not believe the first law was intended to assert the existence of inertial frames of reference, else Newton would have said that explicitly. I think you may be extrapolating from Einstein.
More likely, the first law was intended to correct the then widespread Aristotelian conviction that all terrestrial motion eventually ceases.
I do not believe the first law was intended to assert the existence of inertial frames of reference, else Newton would have said that explicitly. I think you may be extrapolating from Einstein.
More likely, the first law was intended to correct the then widespread Aristotelian conviction that all terrestrial motion eventually ceases.
However, as a standalone statement it is vacuous.
https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#First