Was Uniformitarianism "Scientific"?

The fundamental concepts in geology which construct a coherent story of Earth’s history are often overlooked, oversimplified, and misunderstood. This is especially the case in the geology classroom where teachers must skim over nuance and relate tales of a dichotomous battle between ideas and their champions, one which is true and the other false. By the wonders of the scientific method, students are taught, the truth once again triumphs over irrationality, superstition, and pseudo-science. The battle between catastrophism and uniformitarianism is the quintessential struggle taught to students of geology. While it’s true that these two ideas are indeed at odds with one another, the most grievous error is not in teaching that one ‘lost’ and the other ‘won’, or that one was ‘true’ and the other ‘false’, but in teaching how the thinkers of the time enmeshed in the debate actually came to their conclusions by either applying, mis-applying, or not applying the scientific method. Most of them, on both sides of the debate, implemented versions of the scientific method in essentially the same way, attempting to value above all empirical evidence and implementing a complex and messy combination of induction, hypothetico-deduction, falsificationism, and more. However, the primary wedge between these thinkers, I believe, was in which types of observations an individual chose to favour, modern day processes or geologic features, and how that influenced their perception on the uniformity of natural causes and their associated intensities.

By the height of the debate in the 19^th century, disagreements existed not just over the legitimacy of the incumbent perspective, catastrophism, but over its actual definition. Generally speaking, catastrophism describes the popular perspective that saw Earth’s history as one of punctuated change caused by natural forces which fluxed greatly in intensity and may or may not resemble those natural forces observed today. Catastrophists were trying to explain what they observed in the rock record which, showing “fossils in sedimentary rocks, deformed, cross-cut, and overturned beds, as well as the extinction of species and replacement by more advanced forms”, intuitively indicated catastrophic events (King, 1975). Empirical observation of the rock record would likely cause any observer to adopt a catastrophist explanation as William Whewell most aptly describes:

“THAT great changes, of a kind and intensity quite different from the common course of events, and which may therefore properly be called catastrophes, have taken place upon the earth's surface, was an opinion which appeared to be forced upon men by obvious facts (Whewell, 1967).”

Catastrophists were often divided over what role observable modern forces played in the past, since it seemed obvious to assume that, say for example, water has always eroded rock though it’s questionable as to how rapid that erosion has occurred in the past (Hooykaas, 1970). What did unite proponents of catastrophism, however, was a sense that the individual should not limit explanations of the past simply to his or her lived experience.

The winners of this debate, as is often subtly suggested, were the uniformitarianists, who through supposedly strict empirical observation and induction saw the ‘present as the key to the past’. Uniformitarianism, popularized most by James Hutton and Charles Lyell, tried to explain the past in terms of the observable forces today. Why should one assume that the laws of nature were any different in the past then they are today? For the laws of nature are constant, calculated, balanced, and well-designed. Hutton believed in a type of dynamic stability where even the extant species in his time existed throughout all history (Hutton, 1795). His ideas seemed not only logical but useful since the predictive abilities of the natural sciences depend on stable conditions. Hutton argued:

“Therefore, there is no occasion for having recourse to any unnatural supposition of evil, to any destructive accident in nature, or to the agency of any preternatural cause, in explaining that which actually appears” (Hutton, 1795).

While Hutton admitted that there may indeed have been some major variations in the past, Lyell was not so forgiving. His firm stance on uniformity is seen even in the title of his famous book Principles of Geology: An Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes now in Operation. This piece even influenced Charles Darwin and the development of his thoughts on natural selection (Hooykaas, 1970). The stability offered by the principle of uniformity proved highly productive in uncovering the past by providing not just a foundation to other geologic conundrums, but biological ones as well.

While explaining uniformitarianism as ‘the present is the key to the past’ is convenient, it oversimplifies the concept and one might be shocked that the catastrophist vs. uniformitarianists debate raged on with such vigor and for such a length of time. The debate centred around 2 main components, cause and intensity. First, are the causes observable today sufficient to explain past phenomenon? Second, did any causes in the past occur with a similar intensity as we observe today? Adding further to the complexity of the debate was that the answers to both of these questions need not be strictly either a yes or a no. For example, Lyell, the strictest of uniformitarianists, would answer a resounding ‘yes’ to both these questions. The natural causes we observe today and the intensity at which we observe them in the present moment, are the same as have always occurred in the past. On the other hand, Georges-Louis Leclerc, Comte de Buffon, who one could classify as a catastrophist, argues that nature is "not absolutely uniform" since the “general causes” like air and water are responsible for slow and gradual changes throughout time, however, rapid changes are also caused by things like earthquakes (Hooykaas, 1970). Why should we assume that the most influential causes in the past, would be in operation in the same form today?

At the root of the disagreements on the uniformity of causes and their intensities, were critical divisions over which types of observations to prioritize, modern day processes or geologic features. Lyell prioritized observations of modern-day processes. To be clear, Lyell did observe geologic features and was concerned with explaining how they formed (Hooykaas, 1970). But he was adamant that one must start with observations of modern-day processes and their effects, and then, by analogy explain the features one sees (Hooykaas, 1970). Lyell describes how this process had helped geologists explain the trappean formations:

“By what train of investigations were geologists induced at length to reject these views, and to assent to the igneous origin of the trappean formations? By an examination of volcanoes now active, and by comparing their structure and the composition of their lavas with the ancient trap- rocks. (Lyell, 1830)”

In contrast, Georges Cuvier, one of the most famous catastrophists, focused primarily on the geologic features he observed and then tried to envision the formative forces. Having observed the awesome crustal structures in the Alps and elsewhere, Cuvier could not imagine how the relatively weak passive forces that shape the Earth today, could ever create such phenomena (King, 1975). "It is in vain that we search among the powers which now act at the surface of the earth, for causes sufficient to produce the revolutions and the catastrophes, the traces of which are exhibited by its crust", he exclaimed (Hooykaas, 1970). While Lyell, Cuvier, and the rest of those enmeshed in the debate thought each type of observation to be important, a proclivity towards one or the other was likely to nudge them to a different methodology and different outcomes.

Lyell tried his utmost to employ a strictly inductive methodology, in fact despising the a priori approach. But he also utilized a much more heterogeneous method including strict deduction, hypothetico-deduction, aspirations of falsifiability, and other nuanced approaches. Deduction starts at a grand universal metaphysical truthful premise to infer a necessarily true conclusion. Induction, by contrast, works from repetitive empirical observations of the specific to establish expected probable outcomes. This is often, as it was for Lyell, the idealized scientific method. One free from bias, in which one simply observes without any other aim than to understand. Deduction or induction might provide satisfactory results. However, hypothetico-deduction and falsifiability may actually play a larger role. Determining which of these methods is ‘better’ is subjective, that is to say, contextual, and an awareness of the strengths of each in relation to specific contexts can aid in understanding the history of scientific development and its effective uses.

Lyell was, in many cases, starting with hypotheses and inferring through deduction. Starting with a hypothesis is a dangerous, although sometimes highly rewarding game. William Whewell described the way in which this game occurs:

“They detect the order and connexion which exist, by conceiving imaginary relations of order and connexion which have no existence. Real discoveries are thus mixed with baseless assumptions; profound sagacity is combined with fanciful conjecture; not rarely, or in peculiar instances, but commonly, and in most cases; probably in all, if we could read the thoughts of discoverers as we read the books of Kepler. To try wrong guesses is, with most persons, the only way to hit upon right ones. The character of the true philosopher is, not that he never conjectures hazardously, but that his conjectures are clearly conceived, and brought into rigid contact with facts” (Whewell, 1967).

Lyell was so adamant and convinced of the principle of uniformity, that he would interpret all his observations through the lens of this hypothesis. He was in fact, “convinced of the undeviating uniformity of secondary causes; and, guided by his faith in this principle” (Lyell, 1830). All of his observations, no doubt, would be collected and interpreted in relation to this hypothesis. Luckily, he had landed upon a hypothesis with enough ground in reality that it proved extremely useful in understanding and interpreting geologic phenomenon. But as Whewell stated, a hypothesis, as wild as it may be, must at some point be “brought into rigid contact with facts” (Whewell, 1967). How is this often done? Through falsification.

Karl Popper is known for formalizing the concept of ‘falsification’, the important component he believes that distinguishes science from pseudo-science. Truly scientific propositions must be susceptible to observations that prove the statement incorrect. In the 19^th century, Hutton’s or Lyell’s claims of uniformity were not easily falsifiable. For example, how could one falsify Hutton’s claims that "all we now see around us is only the last link in the chain of phenomena arising out of a uniform causation, of which we can trace no beginning and of which we see no prospect of an end" (Hutton, 1795)? How could that reasonably be tested in a time before radiometric dating? Neither the age of the Earth nor the rate of change were known. Since catastrophists tended to assume that the observed causes and their intensities were far greater than today, they could imply a young Earth. However, Lyell needed a long Earth to explain how the complex geologic features formed given such a low intensity of causes. The ability to test things often depends on the methods, resources, tool, technologies, and foundational knowledge available. I don’t believe that Lyell’s claims are properly testable or falsifiable. According to Popper, untestable statements, though not meaningless, could not be considered as scientific (Popper, 2005). And here in lays a conundrum: If Hutton’s or Lyell’s claims of a uniform Earth without a beginning or end were not falsifiable, were they scientific? According to the requirement for falsifiability, I’d say the answer is ‘no’. But the positive revolutions in the advancement of geologic and biological knowledge that resulted directly from uniformitarianism demonstrate, maybe not its truthfulness, but rather its utility. Maybe then, a more important measure of scientific merit is not its immediate testability and falsifiability – uniformitarianism eventually met these standards once the proper tools were developed and has in many ways been falsified (Romano, 2015). Maybe parsimony and universal utility are of greater importance– Darwin found uniformitarianism and especially its old Earth implications, to provide a useful framework within which to build his ideas. Falsifiability as a requirement, though necessary in many situations, might not provide enough flexibility to scientific conundrums.

Approaching the history of science with narrative of winners and losers, truth and fiction, science and pseudo-science, induction and hypothetico-deduction, might seem appropriate. However, it over-simplifies a complex and convoluted reality. Uniformitarianism neither lost nor won. Lyell, though he claimed to use a strictly inductive scientific method, often deduced from general hypotheses. According to Popper’s criterion, uniformitarianism in the 19^th century, may not even be scientific. Instead, identifying first which types of observations each thinker gave priority to, modern day processes or geologic features, sheds light on how differing opinions or methodologies might even arise.

References

Hooykaas, R. (1970). Catastrophism in geology, its scientific character in relation to actualism and uniformitarianism.

Hutton, J. (1795). Theory of the Earth With Proofs and Illustrations, Volume 1 (of 4). Project Gutenberg. http://www.gutenberg.org/files/12861/12861-h/12861-h.htm

King, H. M. (1975). Critique of the Principle of Uniformity. In C. C. Albritton (Ed.), Philosophy of geohistory : 1785-1970. (pp. 225–255). Dowden, Hutchinson & Ross.

Lyell, C. (1830). Principles of Geology: An Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes now in Operation (J. Murray (ed.); NEW AND EN). D. APPLETON & CO.

Popper, K. (2005). The Logic of Scientific Discovery. Routledge.

Romano, M. (2015). Reviewing the term uniformitarianism in modern Earth sciences. In Earth-Science Reviews (Vol. 148, pp. 65–76). Elsevier B.V. https://doi.org/10.1016/j.earscirev.2015.05.010

Whewell, W. (1967). History of the inductive sciences, from the earliest to the present time. John W. Parker.