Uniformitarianism, earth system science, and geology

Abstract If logic is viewed as a normative science of right reasoning, then various forms of uniformitarianism introduced in the late 18th and 19th centuries were logically flawed at their inception. As noted by William Whewell in 1833, a priori metaphysical assertions about nature are always highly suspect parts of scientific reasoning. Thus, the extension of such presumptions to predictive Earth systems science is not a defect in regard to the general scientific use of the present in regard to analogical reasoning about the past, or the past in regard to analogical reasoning about the future. Rather, there is a defect in regard to the logical role of both strong and substantive forms of uniformitarianism when applied to all science. However, when properly understood, there is great scientific merit in analogical reasoning that uses the immense reservoir of Earth's past operations to see how the full complexity of that planet's present and future operations combine to produce patterns of process operation that evolve into a future that is increasingly being dominated by human influences. Such reasoning is abductive (or retroductive), and it is both a methodologically useful and scientifically fruitful component for generating understanding that can be further elucidated by the deductive and inductive methods of Earth systems science.