Uniformitarianism

Uniformitarianism, a term introduced by William Whewell in the mid-19th century, refers to a cornerstone of geology. Uniformitarianism is based on the premise that present-day processes have operated throughout geological time. Although the earth is in a dynamic state of change and has been so ever since it was formed, the processes that operate today are the same that shaped it in the past. The expression, “The present is the key to the past” is commonly used to summarize uniformitarianism. Therefore, in order to understand and interpret geological events from evidence preserved in rocks, we must first understand present-day processes and their results. Thus, the earth's past is available to us through understanding the current processes and interpreting them in the strata.

James Hutton (1726–1797) was the precursor of the uniformitarian principle. In his Theory of the Earth he believed that “the past history of our globe must be explained by what can be seen to be happening now” and concluded that “the Earth must be millions of years old.” Unfortunately, Hutton's ideas were not widely disseminated or accepted, so catastrophism, more easily associated with religious doctrines, continued to be the prevailing geological idea well into the 1800s. It was Charles Lyell (1797–1875) who became the principal advocate and interpreter of uniformitarianism after his Principles of Geology was first published in 1830–1833. In this book, one of the most renowned scientific texts ever written, Lyell put forward this principle clearly and concisely, and applied it to the study of the earth's crust. Lyell recognized the tremendous cumulative effect that could have resulted from small, imperceptible changes brought about by still-active geological processes over long periods of time. Not only did Lyell effectively reintroduce and establish the concept of unlimited geological time, but he also discredited catastrophism as a viable explanation of geological phenomena. To model the mountains and valleys, it was not necessary to resort to cataclysms that in a short time would have produced great changes, as catastrophists claimed; weaker forces, acting slowly over long periods of time, were sufficient to explain them. The uniformitarian principle became the underlying philosophy of geology because it provided a much simpler explanation for observed geological phenomena than catastrophism. Philosophers call it the principle of simplicity, or “Occam's razor”: one should not invent unknown or extraordinary causes if the usual known procedures are sufficient.

Although Lyell in his development of uniformitarianism surely did a great deal to further the science of geology, he also misrepresented other contemporary theories and mixed together under the banner of uniformity a variety of disparate claims, some of which have been politely ignored so as to avoid embarrassing a key founder of modern geology. Lyell's concept of uniformitarianism should be separated into two different meanings: methodological uniformitarianism (of the laws and processes of nature) and substantive unifor-mitarism (of the intensity of the processes and the state of the earth). Stephen Jay Gould, paleontologist, evolutionary theorist, and dialectical biologist, claimed that substantive uniformitarianism is [Page 1389]false while methodological uniformitarianism is now a superfluous term that is best confined to the past history of geology.

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