In the epilogue of his last book, The Discarded Image, C. S. Lewis writes about the evolution of his views on evolution

Like many people, Lewis initially assumed (or was taught) that Charles Darwin’s bold new theory shocked the world, smashing the old model of the universe and ushering in the new. But in the course of Lewis’s studies in the history of ideas, he learned this was not actually what happened. Instead, Darwin’s intellectual circles had already largely accepted an evolutionary model of the universe, and were just waiting for the right evidence to confirm it. 

Indeed, Lewis writes, that seems to be the usual way scientific paradigms shift. It’s not, typically, that an inrush of new evidence suddenly destroys the old model. Instead:

The truth would seem to be the reverse; that when the changes in the human mind produce a sufficient disrelish of the old Model and a sufficient hankering for some new one, phenomena to support that new one will obediently turn up. 

“I do not at all mean,” Lewis goes on to say, “that these new phenomena are illusory. Nature has all sorts of phenomena in stock and can suit many tastes.”

Since Lewis does not go into detail about what caused this cosmic mental shift in the years leading up to Darwin, and since those details are not very well known, I think it would be worthwhile to tell the story here.

The Philosophical Foundations 

The developments in human thought that set the stage for the theory of evolution are described in Arthur Lovejoy’s landmark work in the history of ideas The Great Chain of Being (1936), which Lewis cites. 

Prior to the Enlightenment, people did not generally see the world as progressing or evolving, but instead either as devolving from past greatness (e.g., “the Age of Gold”), or as undergoing endless cycles of revival and decay. However, there was an influential idea, dating from the Classical era, that contained the seed of what would later become evolutionary theory: the “Great Chain of Being,” which was the idea that there exists a near-infinite hierarchy of creatures proceeding from the lowest slime mold all the way up to God. 

This doctrine, in turn, was based on the “principle of plenitude,” which held that anything that could exist, would exist. (Otherwise, the world would be imperfect, and it seemed unthinkable that the world would be imperfect.) The principle led to the notion that animal species must exist on an infinitely fine gradient, running the gamut of every conceivable form and habitat. Natural philosophers debated whether there was even such a thing as a distinct “species” at all, since that would seemingly imply unfilled gaps between the species — and there should be no gaps. This model provided a framework and a motivation for scientific discovery: long before actual common descent was assumed, biologists were looking for “missing links” that would fill in the gaps, a process Lovejoy compares to chemists filling in the periodic table. On the basis of this reasoning, it was also assumed that there would be some animal nearest to man. Years prior to On the Origin of Species, P. T. Barnum’s circus was exhibiting some possible specimens.  

This was the first half of the recipe. What was needed to get to a theory of evolution was simply to take this idea of a “chain of being” and apply it across time rather than simply space. Lovejoy writes that “one of the principal happenings in eighteenth-century thought was the temporalizing of the Chain of Being.” 

The “German Plato” Gottfried Leibniz (pictured at the top) was a very early influence in this direction. He theorized that perhaps the plenitude of nature cannot be fulfilled all at once, and therefore had to be instantiated over time instead. As early as 1693, Leibniz suggested that animal species might have changed over time, and that some modern species might have had a common ancestor. In 1710 he suggested that land animals might have evolved from sea creatures. 

The revolution in thought received further help from the most eminent metaphysician of that era, the German philosopher Immanuel Kant. Although Kant did not accept the idea of species evolution, Lovejoy writes that he provided a “temporalized version of the principle of plenitude” in his theory of cosmic evolution.

By the middle of the 18th century, the idea that “nature progresses” was a well-accepted doctrine.  As Edward Young neatly summed it up in his popular poem Night-Thoughts (1742-44): “Nature delights in progress; in advance / From worse to better.”

“Nature,” wrote the biologist Jean-Baptiste Robinet in 1768, “is always at work, always in travail, in the sense that she is always fashioning new developments, new generations.”

The soil was prepared — soon, seeds were sprouting. In roughly the third quarter of the 18th century, Lovejoy writes, evolutionary theories of biology proliferated. 

An Age of Evolution 

With that background, we can turn from Lovejoy’s account of the temporalizing of the Great Chain of Being to the ideas of evolutionary thinkers who influenced Darwin. 

Prior to Charles Darwin, the idea that humans evolved from apes was mainly associated with the Scottish anthropologist James Burnett, Lord Monboddo, who argued for this thesis in his 1774 work, Of the Origins and Process of Language. He based his argument largely on wild travelers’ tales of human-like apes (who kidnapped human girls and kept them as sex slaves! — apparently a very human thing to do) and apelike savages (some of whom were even reported to have tails!). 

Monboddo did not propose universal common descent; rather, he was arguing that apes are actually unevolved members of the human species. (Monboddo presents his hypothesis as an alternative to the idea that the ape “is not a man, but a species betwixt man and monkey.”  Note that the assumption was that, whether apes and men were the same species or not, they were neighbors on the Great Chain of Being.) Yet once you accept that civilized humans arose from apes, it’s a short step to imagining that apes arose from monkeys, and then to the whole theory of universal common descent. Interestingly, Monboddo seems to struggle to avoid this conclusion. After telling us that orangutans use tools, and treating this as evidence of their humanity, he later finds himself embarrassed by the fact that monkeys and lower apes also technically use tools — which he dismisses as mere mimicry. Since this comes across as special pleading, I feel like a sympathetic reader of Monboddo’s book would be almost inevitably drawn to conclusion that Monboddo himself rejected: that humans evolved from apes, and apes from monkeys. It’s not surprising, then, that other thinkers were soon willing to go further. 

One of the first writers to clearly present a complete theory of evolution by descent with modification from a universal common ancestor was Charles Darwin’s grandfather, Erasmus Darwin, in his 1794 medical tome, Zoonomia. Erasmus noted that creatures seemed to adapt to their environments over the course of generations — for example, sheep in cold climates seemed to become woolier than sheep in warmer climates. Combining this fact with the observation that there are many physical similarities (“homologous features,” in the modern terminology) between widely disparate animals ranging from birds to whales, he concluded that all life must have evolved from a common ancestor (Zoonomia XXXIV.4, pages 501-502). 

The elder Darwin followed up his technical account with a poetic rhapsody of evolution, “The temple of nature, or, The origin of society” (1803). He wrote: 

Organic Life beneath the shoreless waves
Was born and nurs’d in Ocean’s pearly caves;
First forms minute, unseen by spheric glass,
Move on the mud, or pierce the watery mass;
These, as successive generations bloom,
New powers acquire, and larger limbs assume;
Whence countless groups of vegetation spring,
And breathing realms of fin, and feet, and wing.

Thus the tall Oak, the giant of the wood,
Which bears Britannia’s thunders on the flood;
The Whale, unmeasured monster of the main,
The lordly Lion, monarch of the plain,
The Eagle soaring in the realms of air,
Whose eye undazzled drinks the solar glare,
Imperious man, who rules the bestial crowd,
Of language, reason, and reflection proud,
With brow erect who scorns this earthy sod,
And styles himself the image of his God;
Arose from rudiments of form and sense,
An embryon point, or microscopic ens!

Meanwhile, across the Channel, the theory of evolution was proposed by another scientist: Jean-Baptiste Lamarck. In a lecture in Paris in 1800, Lamarck presented his theory of universal common descent by modification based on the inheritance of acquired traits.

These evolutionary ideas quickly took root in German circle. Two of the most prominent philosophers of that time, Johann Wolfgang von Goethe and F. W. J. Schelling, were proponents of evolution. They were a bit vague about it, however, which has led some contemporary scholars to suggest that we are anachronistically reading our own ideas about evolution back into their words. But University of Chicago historian of science Robert Richards has convincingly argued that they did, in fact, teach evolution. For one thing, Richards points out, it is simply not true that the idea would be an anachronism in their time. Kant had written about the possibility of biological species evolution in 1790. Although he did not end up accepting it, he did entertain it as a “daring adventure of reason.” Besides, Richards writes, both Goethe and Schelling had read Erasmus Darwin’s Zoonomia, so they certainly were aware of the hypothesis. Thus, when we read from Goethe that “the doctrine of metamorphosis is the key to all signs of nature,” we should take it as it was — an evolutionary assertion. At any rate, this was how Charles Darwin and other writers at the time understood it; they accepted Goethe and Schelling as Darwin’s predecessors. 

By the time Charles Darwin presented his satisfyingly elegant and purely naturalistic model of evolution by random variation and natural selection in On the Origin of Species in 1859, the evolutionary worldview seemed so glaringly obvious to a certain type of intellectual that it seemed strange premodern people hadn’t noticed it. It would be an understatement to say that the time was ripe for a new model — in fact, a new model was long overdue. 

The First Social Darwinism 

The social conditions that must have nurtured this “hankering” (as Lewis put it) for the new model aren’t very difficult to see. 

For one thing, it was an age of political revolution. It doesn’t seem like a coincidence that Lamarck proposed his theory of biological evolution after he had weathered the French Revolution as curator of the Botanical Garden in Paris. And while the French Revolution was something unprecedented and worldview-shaking, the political upheavals of the era were just one manifestation of a deeper change. Renaissance-era intellectuals had seen themselves as restorers of Classical achievement, but with the invention of the printing press, and the onset of the Age of Exploration, and then the Industrial Revolution, it was becoming very clear that humanity was ascending to heights thitherto undreamt of (technologically speaking, at least). Society was progressing. 

This led to a general spirit of progress, which quickly influenced philosophy and metaphysics. (For example, Lovejoy writes that Voltaire thought the philosophical model of a fundamentally changeless world was hopeless, because it left no room for progress.) It was only a matter of time before biology was influenced too.  

It’s probably no coincidence that Lord Monboddo was a scholar of linguistic evolution, which was at that time a new field. And in his book (page 366), he explicitly argues that the narrative of human history is one of progress, and is not merely cyclical. What Monboddo saw in society, he applied to biology. 

Nor does it seem like a coincidence that Erasmus Darwin’s famous poem was largely concerned with the evolution of society (it’s in the title), not merely organic life. The rapid technological development of society happening before everyone’s eyes was the model and inspiration for the theory of biological evolution. 

(Conversely, the metaphor of a biological organism was used to explain the structure of human society. For example, the evolutionary biologist and philosopher Herbert Spencer correlates various features of anatomy and physiology with human society in mind-melting detail in his 1860 work The Social Organism.)

Thus, decades before Darwin set out on the H. M. S. Beagle, society was already in the grip of “social Darwinism” — but a different, more optimistic, social Darwinism than what we’re familiar with today, and propounded by a different Darwin. Erasmian Social Darwinism, as we might call it, was a vision of Nature and human history as a magnificent unfolding, a flowering, an inexorable progression to ever-more-dizzying heights. The sociology and the science were two sides of the same coin, and they were mutually reinforcing: just as Nature had been newly made in the image of a progressing human society, humans were now admonished to imitate Nature and strive for progress. 

A Beatific Vision

Rather than treating this as an interesting story from history, it’s worth considering how that beatific vision may be affecting us now. We have certainly not gotten past it. It is a part of Darwinism’s “social armor,” as historian of science Michael Flannery calls it. Because regardless of whatever setbacks the progressive vision might have encountered in the last few years or decades, we are still undeniably in a progressive era of human history. Each preceding generation still seems technologically primitive to the one that follows it. Therefore, a progressive, evolutionary worldview still seems intuitively reasonable to most intellectuals. 

That will not likely be the case forever — nothing in this world goes on the same way forever. But in order for a devolutionary worldview or a cyclical worldview (or something else) to seem intuitively obvious again, there will probably first need to be a serious and sustained decline in human civilization. 

When that happens, we will develop a hankering for a different Model. And Nature, once again, will be happy to oblige.