“The world is so full of a number of things, / I’m sure we should all be as happy as kings.” So wrote Robert Louis Stevenson in his poem “Happy Thought.” It’s a little gem in his A Child’s Garden of Verses, written in 1885 and never out of print. I’ve known the line since I was a child. There are, after all, things of one’s childhood that are far from childish!

But Stevenson’s happy thought sparks “grown up” questions. In coming to grips with them, I find myself wrestling with “the great chain of being.” Let’s begin with the questions (none of which would occur to a child playing a computer game). I’d like to pose a half dozen in all, in two sets of triplets.

The first set begins with the question of whether the world, that is, the universe, is completely full of things. If a vacuum is impossible, as Aristotle argued in his Physics, the answer is yes. In contrast, contemporary physics suggests that there is a multiplicity of vacuums, but they are unstable! So where does that lead us? Waiting for a paradigm shift?

Meanwhile the principle of plenitude, stemming from Plato, tells us that the universe is full of every possible form of existence. Well, maybe. But whatever has existed can possibly exist. Nonetheless, and sadly, whole species have gone out of existence on our precarious planet. The International Union for the Conservation of Nature estimates that upwards of 48,000 species are at risk of extinction.

The evidence of species loss in Charles Lyell’s The Principles of Geology (1833) so troubled Alfred Lord Tennyson that he wondered how a good God could allow Nature to be so ruthless. With whole species in view, his poem In Memoriam laments:

“So careful of the type?” but no.
From scarped cliff and quarried stone
She cries, “A thousand types are gone;
I care for nothing, all shall go.”

Yet Tennyson never supposed that we ourselves contribute to the extinction of many species. How late we are in appreciating that God’s creation calls for our stewardship.

Thomas Aquinas, to be sure, sees the universe as God’s free creation. As such, with respect to its essential identity, it could not be better than it is. Indeed, in ST I, q. 25, Thomas teaches that God “cannot make a thing better than it is itself” any more than he can make a number larger than itself. Nonetheless, God could “give to things made by Him a better manner of existence as regard [their] accidents.” He adds that “God could make other things, or add something to the present creation, and then there would be another and better universe.” Thus nuanced, he seems to accept the principle of plenitude. Even so, Thomas did not think that a species, the first instance of which God directly creates, could become extinct in the natural order of things.

The next two items in the initial set of questions help to clarify the principle of plenitude. Let’s ask, then, whether whatever exists is in continuity with something else. Of course, everything is what it is and not something else. But there must be some continuity unless there are gaps in reality, in which case we revisit the question of whether nature abhors a vacuum. At the macro-level, nonetheless, there is a broad continuity in shared properties. Rocks and robots, as well as radishes and rats, are materially individuated. Mice and men share externally caused sensations. Men and angels are rational, though in different ways.

The last question in my initial set, whether the universe exhibits diversity, is an easy one. If it contains every possible sort of existence, then it exhibits maximum diversity. We needn’t worry that there are a boringly few sorts of existence. Nor is the universe stuffed with repeats!

And now, gentle reader, allow me to introduce—I can do no more here—the other triplet of questions occasioned by the great chain of being and the principle of plenitude. First comes the question of whether Scripture in any way reflects such concepts. Next is the question of whether we can resolve the problem of evil by an appeal to this universe as being the best it can be. Third, and last, is the question of whether the great chain of being suggests an optimal political order.

Yes, Scripture does reflect such a vision. Recall the order of Creation in Genesis and how the psalmist praises it:

O Lord, how manifold are your works!
In wisdom have you made them all;
The earth is full of your creatures. (Psalm 104:24)

Consider next the problem of evil. Given the overarching scheme of things in the great chain of being, might what we take to be evil be only a shade of darkness that serves to highlight the brilliance of endless lights? Some have thought so.

Finally, turning to the sphere of politics, royalists have seen the great chain of being as a warrant for the supremacy of kings. Liberals might counter that the democratic state, as the topmost agency of the people, is equally warranted. And surely a case for a calibrated political subsidiarity is an option. If nothing more, history tells us that there has been a plenitude of political arrangements!

So much for introductions. Future posts will find me exploring each of them in turn.