Assumption that the natural laws and processes of the universe are constant through time and space
Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle,[1] is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in the past and apply everywhere in the universe.[2][3] It refers to invariance in the metaphysical principles underpinning science, such as the constancy of cause and effect throughout space-time,[4] but has also been used to describe spatiotemporal invariance of physical laws.[5] Though an unprovable postulate that cannot be verified using the scientific method,[6] some consider that uniformitarianism should be a required first principle in scientific research.[7] Other scientists disagree and consider that nature is not absolutely uniform, even though it does exhibit certain regularities.[8]
In geology, uniformitarianism has included the gradualistic concept that "the present is the key to the past" and that geological events occur at the same rate now as they have always done, though many modern geologists no longer hold to a strict gradualism.[9] Coined by William Whewell, uniformitarianism was originally proposed in contrast to catastrophism[10] by British naturalists in the late 18th century, starting with the work of the geologistJames Hutton in his many books including Theory of the Earth.[11] Hutton's work was later refined by scientist John Playfair and popularised by geologist Charles Lyell's Principles of Geology in 1830.[12] Today, Earth's history is considered to have been a slow, gradual process, punctuated by occasional natural catastrophic events.
^Gould 1965, pp. 223–228, "The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference which, as Bacon showed nearly four hundred years ago, is the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown and, therefore, no way of reaching general conclusions from a finite number of observations."
^Gordon 2013, p. 82; "The uniformitarian principle assumes that the behavior of nature is regular and indicative of an objective causal structure in which presently operative causes may be projected into the past to explain the historical development of the physical world and projected into the future for the purposes of prediction and control. In short, it involves the process of inferring past causes from presently observable effects under the assumption that the fundamental causal regularities of the world have not changed over time."
^Strahler, A.N. 1987. Science and Earth History- The Evolution/Creation Controversy, Prometheus Books, Amherst, New York, USA. p. 194: “Under the updated statement of a useful principle of uniformitarianism it boils down essentially to affirmation of the validity of universal scientific laws through time and space, coupled with a rejection of supernatural causes.” p. 62: “In cosmology, the study of the structure and evolution of the universe, it is assumed that the laws of physics are similar throughout the entire universe.”
^Rosenberg, Alex. Philosophy of science: A contemporary introduction, 4th ed. Routledge, 2019, 173
^Simpson 1963, pp. 24–48, "Uniformity is an unprovable postulate justified, or indeed required, on two grounds. First, nothing in our incomplete but extensive knowledge of history disagrees with it. Second, only with this postulate is a rational interpretation of history possible, and we are justified in seeking—as scientists we must seek—such a rational interpretation."
^FARIA, Felipe. Actualismo,Catastrofismo y Uniformitarismo. In: Pérez, María Luisa Bacarlett & Caponi, Gustavo. Pensar la vida: Filosofía, naturaleza y evolución. Toluca: Universidad Autónoma del Estado de México, p. 55–80, 2015.[1]
^Pidwirny & Jones 1999, "the idea that Earth was shaped by a series of sudden, short-lived, violent events."
^James, Hutton (1785). Theory of the Earth. CreateSpace Independent Publishing.