In antiquity and the Middle Ages, the various branches of philosophy were called sciences. With the rise of positivism in the nineteenth and twentieth centuries, which asserts that empirically reliable knowledge is to be found only in the empirical and experimental sciences, it has become necessary to set investigative science apart for history, from mathematics, and from philosophy. There is no science of science . I wrote a methodological account of philosophy's past, present, and future. There I explained why philosophy has been so late in maturing.
Philosophy has a brighter future in the centuries ahead.
If philosophy did not exist, we would have no moral philosophy as a branch of knowledge and we would have no understanding of science itself, for when scientists write about science, they do so as philosophers, not as scientists.