Similarly, we could say that science is 'whatever studies Nature publishes', but that doesn't tell us much and threatens to leave the mistaken impression that N

Similarly, we could say that science is 'whatever studies Nature publishes', but that doesn't tell us much and threatens to leave the mistaken impression that Nature is merely capricious and arbitrary. While I agree with your conclusion, we shouldn't forget that philosophy and other marketplaces you mention have standards based mostly on what proved to be true in the past, what can withstand argument and criticism in the idea marketplace, and on a commitment to excellence and achievement.