After I posted my piece on the Great Chain of Being I was informed that the definitive treatment of that theme is the 1936 book (of the same name) by Arthur Lovejoy, So I thought I ought to check out how far I’d erred in my ad hoc treatment of it.
Perhaps my biggest omission (justifiable in a simplified blog post, perhaps) was the degree of tension that always existed both between the idea that all nature is connected in a continuous chain and other strands of philosophy and science; and also within the idea itself, especially given its close entanglement with Christian doctrine.
The most important concepts involved in these tensions were those of plentitude and of continuity, both going back to the Greeks but accentuated in mediaeval and early modern Christian philosophy. A strong theme of Christian teaching is that God is free, particularly with regard to creation – he can make what he wants. But, it was argued by many, “what he wants” as the perfect and omnipotent God must be what is best and most perfect, so in fact he creates what there is by moral necessity, and so isn’t free at all. Discuss, for not less than three hundred years…
Going with that was the idea that, in his generosity, God would not refuse to create anything that was possible, and so came the idea that he must have actually created every possible form – the principle of plenitude. In biology (and even mineralogy) that principle explains the following surprising fact:
Thus it was that from the end of the sixteenth to the end of the eighteenth century, the project of distributing all living things, animal or vegetable, into a heirarchy of collective units enclosed one within another, gained such a hold upon naturalists, that it finally seemed to them the formulation of their scientific task. (Daudin, quoted by Lovejoy p.288)
Did you spot that? The whole business of biology, for 250 years before Darwin, was describing nested heirarchies in order to demonstrate the truth of what was believed about God’s goodness. So (as I discussed with Argon on a BioLogos thread recently) the fact that evolutionary theory predicts nested heirarchies is true, but was equally and antecedently true of early modern theistic Platonic fixism. In fact, when Hydra was (re)discovered in 1739, and held up as the missing link between vegetables and plants, it was said that Leibniz was:
…the German Plato, who did not live to know of the actual observation [of this organism] yet through his just confidence in the fundamental principles which he had learned from nature itself, had predicted it before his death.
Likewise, it is little realised that the quest for the human “missing link” was pursued enthusiastically from the late seventeenth century, giving rise to the then largely pseudo-science of anthropology long before evolution was proposed. Isn’t it sobering to think that, had Leibniz or his fellow believers in the theological necessity of plenitude known of Tiktalik, it would have amply confirmed their view of the universe as God’s “best of all possible worlds”?
Another, related, surprise from Lovejoy is that the big revolution in astronomical thought was not Copernican heliocentrism at all, but the later dissolution of the sphere of fixed stars and its replacement with the belief in an infinite universe of stars and planets like ours.
Did this “new astronomy” undermine an entirely anthropocentric Christian worldview? Not at all. On the same principle of plenitude, it demanded a universe teeming with life, handily accounting for the gaps in forms observed by biologists here. It was also reasoned that many of these celestial beings would be far greater than us, thus filling the yawning chasm between our own lowly attributes and those of God, and incidentally explaining twentieth century science-fiction’s assumption that aliens would generally be more advanced than us.
So in the second half of the seventeenth century discussion of ET life was a commonplace, making a quote I’ve previously used here from Puritan Richard Baxter actually pretty sober and cautious.
Nowadays, it’s widely assumed that the discovery of ET life, by confirming life to be a routine natural phenomenon, would undermine belief in God. But it is as much a prediction of Platonic theism as are nested biological heirarchies. The lessons, I guess, are that fulfilled prediction alone is not a demonstration of a prophet of truth – and also that the origins of our common assumptions aren’t always what they seem. Paradoxically, the failure to find life on every body in the solar system, by undermining the principle of plenitude, also threatens a certain view of God that prevailed amongst intellectuals for several centuries.
A further example of this is in the idea that was often associated with plenitude – that of continuity. One of the tensions within early modern “Chain of Being” philosophy was that both Plato and Aristotle had perceived reality to be based on forms. In Christian culture these naturally became ideas in the mind of God, corresponding to species of all kinds.
But at the same time (and with a degree of contradiction) the ancient philosophers had conceived that only an infinite number of forms would fully represent “the good”. As it happened, the latter idea had most appeal in early modern times, and the belief that there were no truly universal forms, but instead an infinite gradation, predominated in scholarly circles. It underpinned Newton’s differential calculus, and was rendered as an aphorism by Leibniz: Natura non facit saltum – nature doesn’t make a jump.
Nature doesn’t jump, in the predominant mindset of those days, not because it would be unnatural or miraculous, but because it would leave gaps in the perfect fullness of the good and omnipotent God’s work. Nature doesn’t leave gaps because God makes everything that is possible. Incidentally, the saying “Nature abhors a vacuum” is likewise a statement of philosophical faith in plenitude: if the universe is not chock full of created things, God’s infinite goodness is in doubt.
That is what makes quantum theory such a philosophical bombshell: it appears that quantum events are saltations unlinked to the rest of nature.To me that’s not a problem, because I prioritize God’s freedom to choose events over his obligation to do everything possible – but I am not a card-carrying Platonist.
Leibniz’s strong religious faith, however, would be more severely shaken by QM than Einstein’s agnosticism was. That is, until he heard of the Many Worlds Interpretation, ie that every quantum possibility is actually realised, leading to the budding off of an infinity of alternate universes containing all possible events and entities. At that point he’d have been on theological Cloud Nine chortling “I told you so!” There could be no better evidence than the Multiverse for the God of the philosophers, though his connection to the God of Christianity is dubious.
Here’s one more intriguing strand of thought. And that is that Charles Darwin was born into an intellectual world in which plenitude and continuity held strong, and even axiomatic, sway. It is not in the least coincidental that in Origin of Species he quotes a variant of Leibniz’s dictum, Natura non facit saltus no less than six times, to stress the centrality of gradualism to his theory.
We miss its philosophical significance because we live in different times. Doubtless Darwin’s hold on the theological end of God’s goodness was weakened by his increasing loss of faith, but it didn’t alter his then orthodox view of nature as requiring a literally infinite range of virtually inseparable forms in order to be complete. His early chapter on the artificiality of species was entirely of a piece with the arguments for continuity going back to mediaeval times. Gradualism over near-infinite time was, or at least could be for a reading public steeped in the Chain of Being, another way (like infinite space) for plenitude to be demonstrated as true.
And putting Darwin in the historical context of the doctrine of plenitude suddenly makes his “endless forms most beautiful and most wonderful” more than a catchy turn of phrase. The “grandeur of this view of life” was a type of grandeur shared by the majority of scientific theorists, from Cusanus in the Renaissance, through Bacon, Newton and Descartes and, of course, Leibniz.
It’s a little ironic, then, that the principle of plenitude – which was from the start a result of a priori reasoning about both the universe and God rather than observation – has received a number of setbacks in recent times. Quantum theory, as I’ve said, shows that after all, natura facit saltum, if the many-worlds interpretation be regarded as unparsimonious and local variables as false.
Astronomically, the knowable universe is not infinite, the solar system appears empty of life, SETI has drawn a blank and the Fermi paradox has us wondering where God has hidden all the plenitude.
Regarding life, Wikipedia (commenting on “natura non facit saltus”) says:
In the biological context, the principle was used by Charles Darwin and others to defend the evolutionary postulate that all species develop from earlier species through gradual and minute changes rather than through the sudden emergence of new forms. Modern evolutionary biology has terminology suggesting both continuous change, such as genetic drift, and discontinuous variation, such as mutation. However, as the basic structure of DNA is discrete, nature is now widely understood to make jumps at the biological level, if only on a very small scale.
What is being challenged, of course, is not empirical science but a millennium or so of philosophical assumption based, ultimately, on Greek speculation. Much early-modern science was built on such axioms as the Chain of Being, plenitude and continuity. Modern science has been built, of course, on those early-modern foundations. You have to wonder how many of the philosophical assumptions are still dictating habits of thought, both in the sciences and in theology.