The Non-Linearity of the History of Science

As I mentioned in my last post, in a history of biology course I am sitting in on we were discussing Cuvier, and if we were discussing Cuvier, we were probably also discussing catastrophism vs. Lyell’s uniformitarianism. Which is true.

The story that is frequently told about this debate and its influence upon Darwin is, as is usual, simpler and a lot less interesting than what actually happened.

Catastrophism was a geological theory that claimed that the planet had experienced large-scale… catastrophes… that completely changed the world rather quickly. No one living at the time, or for the past few thousand years, had ever experienced these kinds of events. Frequently catastrophism was linked to Biblical events such as Genesis and Noah’s Flood (and in the future, Armageddon), but there were scientific reasons to believe catastrophism was true (but I am not currently aware of them). Cuvier avoided Biblical talk in his own catastrophic ideas, arguing for more regional (rather big regions, mind you, but not global) disasters that didn’t wipe out the entirety of existence.

The English geologist, Charles Lyell, constructed the theory of uniformitarianism – a theory very much opposed to catastrophism. Lyell argued that catastrophism was unscientific, but Stephen Jay Gould, in an essay in Ever Since Darwin points out that Lyell was attacking Biblical catastrophism which is somewhat of a strawman. I don’t know the details here so I can’t tell you what the scientific evidence was for or against catastrophism .

Lyell’s uniformitarianism postulated that processes acting today are the same processes that acted yesterday. Instead of mountains rising or canyons furrowing rather suddenly, as the catastrophists believed, Lyell argued that everyday earthquakes and river erosion acting gradually were sufficient to explain these natural formations.

As is typically said in histories of science, Lyell’s uniformitarianism paved the way for Darwin’s theory of evolution.* Special Creation can be construed as a biological form of catastrophism – God, in six days, created all of the life that now exists today, and is an event that we do not experience in our daily lives. Evolution, on the other hand, is obviously not catastrophist as the process happens all around us on a continuous basis, even today. We can explain what happened yesterday by examining what is happening today.

There is an aspect of Lyell’s uniformitarianism that is frequently ignored, however, and it formed a rather large part of Lyell’s worldview. Gould called this tenet the “dynamic steady-state.” It is almost like the Law of Conservation of Mass and Energy, but applied to geology. In regards to land mass, Lyell believed the size of today’s landmass is the same as yesterday’s; the distribution may have changed, but the total amount has remained. Because climate wasn’t “conserved” due to the landmasses moving about the globe, he was able to accept some form of transmutation of species. (Because the continents moved around, Lyell had a cyclical view of history in which biological eras, such as “the age of reptiles” and “the age of mammals,” would also cycle.)

Leaving out the dynamic steady-state in the history of Lyell’s impact on Darwin’s theory of evolution is misleading. The typical story casts the catastrophists in a negative light, even though they were correct about a linear history of the planet. Darwin had to abandon a major tenet of Lyell’s theory to construct his own theory of evolution. The idea of “progress” was “in the air” in Darwin’s time, so I have no idea if the catastrophists’ beliefs regarding linear time influenced him at all, but it would be interesting to check whether or not that is the case. But in any case, there wasn’t a simple jump from uniformitarianism to Darwin’s theory of evolution; instead, Darwin had to eliminate one of the central tenets of Lyell’s theory in order for his to make any sense.

(As for which school of thought is true, modern geology is a mixture of both. Canyons and mountains are generally formed by uniformitarian processes, but asteroids slamming the earth and causing mass extinctions is clearly a catastrophic event. Depressingly, one of the lectures by the creationist Terry Mortenson I saw last spring was focused on disproving uniformitarianism and proving catastrophism. As with all false dichotomies, neither is exclusively true and the answer is somewhere in the middle. The dichotomy is especially false because Mortenson labels modern geology as exclusively uniformitarian when in reality, it’s he who is the oddball extremist.)