Lyell's Pillars of Wisdom

Natural History, April, 1999 by Stephen Jay Gould

Second, the claim for a nondirectional or steady-state earth: Standard geological causes (erosion, deposition, uplift, and so on) show no trend either to increase or decrease in general intensity through time. Moreover, even the physical state of the earth (relative temperatures, positions of climatic belts, percentages of land and sea) tends to remain roughly the same or to cycle around and around through time. Change never slows or ceases; mountains rise and erode; seas move in and out. But the average configuration of the earth experiences no systematic trend in any sustained direction. Lyell even believed at first--although he changed his mind by the 1850s, when he finally concluded that mammals would not be found in the oldest strata--that the average complexity of life had remained constant. Old species die, and new species originate (by creation or by some unknown natural mechanism). But clams remain clams, and mammals, mammals--from the earliest history of life until now.

When a scientist proposes such a comprehensive system, we often gain our best insights into the sources and rationale for his reforms by explicating the alternative worldview of his opponents. New theories rarely enter a previous conceptual void; rather, they arise as putative improvements or replacements for previous conventionalities. In this case, Lyell's perceived adversaries advocated an approach to geology often called either catastrophism or directionalism (in opposition to Lyell's two chief tenets of gradualistic change on an earth in steady-state).

Catastrophists argued that most geological change occurred in rare episodes of truly global paroxysm, marked by the "usual suspects" of volcanism, mountain building, earthquakes, and flooding. Most catastrophists also held that the frequency and intensity of such episodes had markedly decreased through time, thus contrasting a feisty planetary youth with a much calmer present.

For most catastrophists, these two essential postulates flowed logically from a single theory about Earth's history--the origin of the planet as a molten fireball spun off from the Sun (according to the hypothesis, then favored, of Kant and Laplace), followed by progressive cooling. As this cooling proceeded, the outer crust solidified while the molten interior contracted continuously. The resulting instability--caused, almost literally, by an enlarging gap between the solidified crust and the contracting molten interior--eventually induced a sudden global readjustment as the crust fractured and collapsed upon the contracted molten core. Thus, directionalism based on continuous cooling linked the catastrophism of occasional readjustment by crustal collapse with the hypothesis of a pervasive "arrow of time" leading from a fiery beginning, replete with more frequent and more intense paroxysms, to our current era of relative calm and rarer disruption.

Incidentally, this account of catastrophism as a genuine and interesting scientific alternative to Lyellian uniformity disproves the conventional canard, originally floated as a rhetorical device by Lyell and his partisans but then incorporated uncritically as the conventional wisdom of the profession. In this Manichaean account, catastrophism represented the last stronghold for the enemies of modern science: the struggle of theologically tainted dogmatists to preserve both the literal time scale of Genesis and the miraculous hand of God as history's prime mover by invoking the doctrine of global paroxysm to compress the grand panoply of geological change into a mere few thousand years. In fact, by the 1830s all scientists--catastrophists and uniformitarians alike---had accepted the immensity of geological time as a central and proven fact of their emerging profession. Catastrophists upheld a different theory of change on an equally ancient Earth, and their views were no less "scientific"--and no more theologically inspired or influenced--than anything touted by Lyell and his school.