Leibniz and his great task

A review of G.W. Leibniz:  Philosophical Essays, translated by R. Ariew and D. Garber

“I have found that most sects are correct in the better part of what they put forward, though not so much in what they deny.”  — Leibniz

Leibniz was the the great ecumenist of the seventeenth century.  A very Catholic-friendly Lutheran, he credits some of his key insights to Thomas Aquinas and Teresa of Avila and invokes the relativity of motion to defend, or at least reduce the significance of, the condemnation of Galileo.  However, most of his effort he devotes to the ominous gap opening between scholastic philosophy and the “new philosophy” of Descartes and the science of mechanics.  Leibniz had made his own contributions to mechanics as co-discoverer of calculus and the discoverer of kinetic energy, but he was convinced that the Cartesian reduction of matter to geometry had unacceptable implications; philosophy needed to rediscover substantial forms and final causes.  How to connect these to mechanics?  In some of his writings on dynamics, he tries to connect a substance’s “striving” or “active force” with substantial form and with (what we would now call) kinetic energy, while the substance’s resistance to being acted on is connected to primary matter and mass.  This, unfortunately, is subject to the same critique Leibniz levels against the Cartesians who had gave primacy to (what we would now call) momentum.  Leibniz denies absolute space and any preferred reference frame.  Space is, he thinks, an abstraction describing the reality of relations between bodies.  (To make this work, he denies that a vacuum is possible.  How could things be separated except by some thing?)  But kinetic energy is as frame-dependent as momentum.  The real interest here is what Leibniz is trying to do, to rediscover a connection between Aristotelian metaphysics and incipient modern physics.

Of more lasting philosophical interest is his investigation into the nature of substantial forms, or monads, as he calls them.  Monads are, to use his wonderful term, metaphysical atoms, the basic ontological blocks out of which the world is made.  Each is unitary and indivisible, but a world unto itself, a distinct reflection of the entire universe from its own unique perspective.  Monads have become famous for being “windowless”, but it could equally be said that each one just is a window, or rather a mirror, containing everything else within itself.  The human soul is a monad, but so are animal souls, and indeed infinite numbers of monads are everywhere, and all the world is alive with them.  Never has a philosopher paid less heed to the principle of parsimony–and why should he, when by his own argument God must have made the most perfect and diverse universe possible?

In Leibniz’s logic, the predicate is necessarily in the subject.  If one thinks of the subject as a bag of all its predicates, a true statement is just a matter of factoring out some subset as the predicate and connecting it to the subject with “is”.  Leibniz takes this mathematical analogy quite literally; in his early days, he hoped to map properties to numbers and reduce logic to literal factorization.  Here is the origin of Leibniz’s distinctive solution to the problem of individuality and the problem of evil.  Leibniz doesn’t believe in primary matter as the scholastics saw it, as irreducibly unintelligible.  Therefore, Saint Thomas’ argument for the angels, that each incorporeal substance must be its own species, applies to all substances.  Each monad contains all its individuating predicates essentially.  That Caesar crosses the Rubicon is part of his definition; Adam could not have failed to sin, or else he would have been another person (another person named “Adam”, perhaps, but not the person God actually made).  Each monad plays through its destiny by the exigencies of its own nature, while God has ordered each so that everything stays synchronized.  (Leibniz is a little evasive on this point, but that’s my reading.)  At each time, every monad contains its past and future as well as that of the entire universe inside of it, and if all this infinite information didn’t reduce to noise to our finite minds, we could see the foreshadowing of future events, the intelligible unity of each life.

If you’ve followed him this far, why not all the way?  Monads, being unitary, are indestructible and uncreatable, except by divine intervention.  Leibniz thinks it likely that the souls of animals, for example, have some sort of pre-existence and post-existence, albeit miniscule.  Human souls, on the other hand, mirror not only the universe, but God Himself, and for the righteous among these, he intends eternal felicity and fellowship with Him.  Leibniz is the originator of the principle of sufficient reason:  there is always a reason why things are so and not any other way, although some things are necessary because the opposite is contradictory and some because God is constrained always to choose the best.  Thus, although there is much wickedness in the world, we can be sure God chose what will ultimately lead to the greatest good, the greatest order and diversity.

I came away liking Leibniz for the enthusiasm and charitable broad-mindedness that come through in his essays and letters.  He made many lasting contributions to philosophy and mathematics, but judged on his own terms, it was at best a spectacularly creative failure.  By the time the Monadology is done, we have forgotten the original goal of being able to clearly identify substances and their essences; we have only multiplied them to infinity and left the task more hopeless than we found it.  Western conceptions of free will and divine sovereignty continued to drift apart, as did mathematics and metaphysics.  In the next generation, the Enlightenment war against Christian civilization would begin.