Knowledge of an objective reality by whatever science it is developed and extended cannot prove the existence of things apart from all the relations by which they are known. This is like saying, in the case of physics, that the only reality is that of mathematical equations, a view which gains more plausibility as the attempts to imagine kinds of 'material' things which anchor these relations grows more and more incoherent due to quantum phenomena. In other words, naturalism inevitably parts ways with materialism. This differs little if at all from saying that mind can only know mind, and that the respects in which physical reality is unlike our contingent mental reality are of no weight compared to all the respects in which it is mind-like in a larger sense - structured by abstract laws, non-local etc. This argument has its purely subjective version as well: that your world is made entirely out of the meanings with which you understand and engage in it. Whatever is assumed to be left over, unaccounted for, by such a view is only further reaches of meaning. It is mind but not limited by your contingent sense at any time of the bounds of mind. These bounds are always being pushed further out anyway, so there could be no reason to grant them any metaphysical priority. Experience pushed far enough leaves metaphysics behind.