The philosophy of science has always been a part of philosophy and formed part of that of several great philosophers during the ancient and middle ages, even when there was relatively little science around. Modern science itself is heavily influenced by Roger Bacon's philosophy. This was followed by the rationalism-empiricism debate, which lasted approximately until logical positivism synthetised both rationalism and empiricism. Logical positivism developed the philosophy of science to the level of a separate and mature branch of philosophy.