 But then Hempel's paradox of confirmation highlighted that formalizing confirmatory evidence of the hypothesized, universal law "All ravens are black"—implying "All nonblack things are not ravens"—formalizes defining a white shoe, in turn, as a case confirming "All ravens are black".During the 1830s and 1840s, the French Auguste Comte and the British J S Mill were the leading philosophers of science.Debating in the 1840s, J S Mill claimed that science proceeds by inductivism, whereas William Whewell, also British, claimed that it proceeds by hypotheticodeductivism.