Charles Hartshorne
“Leibniz . . . had a very clear head.”
—George Santayana
The Importance of Leibniz (1646-1716)
Karl Popper, who, with Kant, doubts that there has been progress in metaphysics, has told us better than anyone else how intellectual progress is to be made. The method of reason is the method of discussion, consisting in the formulation of definite propositions, open to refutation by appropriate means. If the proposition is empirical, the means are perceptual observations. If it is not empirical, then the means are logical or analytic, conceptual exploration of the relations of ideas to other ideas, or to aspects of experience so general that no observation could conceivably show their absence. The power of the method is proportional to the boldness and clarity of the propositions being tested. He who hides behind obscurity or is noncommittal on controversial issues, and thereby avoids all risk of refutation, is no friend of reason. By these criteria, Leibniz was one of the greatest of philosophers. He was definite and bold; he invited criticism instead of discouraging it. He put more sharply and definitely proposals that others had put vaguely or with evasive qualifications. He made implicit questions explicit and ambiguous answers unequivocal. His position was seen by all the world as startling and vulnerable. What was less well seen is that this was one of its chief values. That some of Leibniz’s doctrines were absurd was easy enough to see. What was so hard to see that for over a century nobody quite saw it, was the opportunity for progress implicit in this very absurdity.
“The real is the individual,” said Aristotle. Very well, said Leibniz, what is individual about air or water? How many individuals in an ocean as such? One, a finite number, an infinite number? Or is all the water in the universe one individual? “Change is the possession at different times of different predicates by an identical subject.” “What makes something identical if its predicates are not identical?” asks Leibniz. “The same matter is there.” And in what consists the sameness of the matter, if its properties change? That some “essential properties” do not change? But how could essential properties, if these are abstractable predicates, universals, individuate a changing’ bit of matter, make it always the same unique entity?
Truth, Leibniz saw, is true of reality, definite truths imply definite realities. If the realities are individuals, then individuals must be definite. But an entity whose identity is independent of properties other than those termed essential seems rather indefinite. Is John sick or well? He may be sick, he may be well; either way is he still John? “At a given time, John is definitely sick or definitely well.” Then is it the actual career of the individual that is definite? But this implies that John’s career is the only one that John could have had, in which case all John’s properties at whatever time are essential, and he has no accidental properties!
\Again, according to Descartes and Spinoza, reality consists of thinking substance and extended substance. Very well, said Leibniz, but what is extension if not a pattern of coexistent elements? What then are the elements? If thinking substances can coexist they must form a relational system and so be extended in whatever sense there is extension. Hence mind and matter cannot be contrasted as Descartes or even Spinoza contrasted them. For if two thinking entities coexist they have spatial relations that just are the way things coexist and fit into the cosmic cause-effect structure (misconceived by Leibniz in his preestablished harmony doctrine).
In all of the foregoing Leibniz invited philosophy to move to a higher level of clarity than it had ever before reached, not necessarily by improving answers to old questions, but by improving questions.
Take another point. “God is perfect,” everyone had said. Also “God created the world.” “Can a perfect creator produce an imperfect creation?” Leibniz wanted to know. If it was said that the world could not be as perfect as God, since then it would be God over again, Leibniz asked “How far short of perfection can the world fall and still express the goodness and power of its producer? Must it not be the most perfect world possible, falling short of divine perfection only insofar as this is inherent in its being a production rather than a self-existent eternal Cause? Must it not be the best possible world?”
Leibniz thought about metaphysics as a mathematician and logician might be expected to think, trying to make traditional proposals definite enough to yield rigorously logical consequences by which one might judge the validity of the proposals. After Leibniz, who seized upon the opportunity this represented? I see no one between Leibniz and Peirce who compares with the former as the latter does in mathematical and logical expertness, combined with the courage to deal with metaphysical questions and a knowledge of the history of metaphysics. After Peirce, Whitehead was the next writer with these qualities.1
What went wrong with Leibniz’s answers to the foregoing questions? The trouble came from some questions he did not put at all but only answered as though they were not questions, not proposals in need of criticism, but sheer axioms. His principle of sufficient reason was one of these, his definition of God as immutable perfection was another, and his assumption that the ultimate units of reality were changing individuals, still another. It never seriously occurred to Leibniz that the principle of sufficient reason has irrational consequences and is opposed to reason or that his definition of God has logical difficulties so that the question is not, “Does God so defined exist?” but rather, (a) “Does the definition express the most important religious values?” and (b) “Is it logically possible that such a being should exist?” Leibniz had a glimmering of awareness as to (b) but not as to (a). He thought religion must stand or fall by the customary definition, just as he thought that rational explanation requires absolutely sufficient reasons and that a pluralistic view of reality requires absolutely definite but changing individuals.
Leibniz was clearly wrong about sufficient reason if practical reason is taken as the paradigm. For it is not a sensible objection to a decision that it is not the best possible one. It is quite enough justification that the decision is as good as any possible one. “Carpenter, that nail you chose out of the box of similar nails was no better for the purpose than some of the other nails in the box, so you should not have chosen it” is a ridiculous pronouncement. If no other nail was better, that fully justifies the choice. Nicholas Rescher has very cleverly defended the maxim: In cases of equally good solutions of a practical problem, act on the first of these equally good solutions that occurs to you. A poet need not claim that his wording of a line (or the color of the ink in which he writes or types it) is the best possible. Unless it can be shown that a still better one was possible he has no cause for regret. “As good as any possible choice” perfectly justifies a choice.
The still deeper error in the famous principle is that it excludes creativity. God’s creating the world is merely his baptizing some one out of the array of all possible worlds as the “real” one. God selects a cosmic pattern already fully in being as a pattern and makes it real. What does this selection of one completely defined world out of many equally definite ones amount to? “Reality” either adds further definiteness or it does not. If it does, then the possible world is as such partly indefinite. If it does not, then what definite difference does it make which world is real? Some contemporary logicians and some contemporary physicists have actually suggested that the only difference between the “real” world and other possible ones is that we are in the former and not in the latter. This reduces decision among possibilities to an absurdity, since what we decide against is still real, in some other world.
Not only does Leibniz reduce divine creativity to mere selection, or to something that both is and is not an addition to the world selected, but he denies even this attenuated form of action to the creatures. They can neither effect the selection of any part of reality out of the array of possibilities nor create definiteness out of the previously indefinite. Yet they are supposed to conceive God as doing at least one of these things. Must we not form our ideas of God from our experience of our own actions or those of other creatures?
To assume without argument, as Leibniz did, that it is individuals that are the definite units of reality, was to overlook the possibility that the really definite units are the momentary states of changing individuals, whose change is the successive creation of these states. Accidental predicates then belong to careers as having at each moment partly indeterminate futures. The past alone is definite, and only dead people have fully definite careers. Moreover, even they could have had partly different careers after the first member of their sequence of states. But to carry out this view one must relax the principle of sufficient reason enough to make room for creative decisions in each new state of given individuals.
With the foregoing revisions and some others of a similar kind, the obvious absurdities of Leibniz’s position disappear. But it took more than two centuries to accomplish this revision.
Psychical Atomism
The Greek atomists had in effect put and answered two questions:
(1) Are the real and primary agents of change in nature things (a) large enough to be distinguished by direct perception or (b) imperceptibly small? (they did not consider the possibility of their being imperceptibly large) and (2) How shall we further characterize the agents, assuming that they are imperceptibly small? Leibniz agreed with the atomists about (1b), except in the case of a macroscopic living organism, in which he thought we could in a sense perceive a dominant agent or monad, preeminent among the other and imperceptible ones. But he disagreed sharply as to the answer to (2). If pebbles or other perceptible inert solids are really swarms of imperceptible active singulars, it is absurd to try to describe the true and active singulars in terms of inert, hard, solid objects, with the lame qualification that, unlike these collective and inert perceived entities, the unperceived ones are genuinely singular and active. Rather we must describe the imperceptible units in terms of the only active singulars we perceive as such: ourselves, other animals, and perhaps—though here Leibniz hesitates slightly—also plants.
In other words, Leibniz was the first very great philosopher to combine the atomistic insight—hinted at by Plato in the Timaeus, but not really used—that the basic all-pervasive forms of change in the world are too subtle to be perceptible to direct vision or touch, with the central Platonic insight that the principle of change or of dynamic unity is psychical, involving at least some of the inherently active functions of thinking, feeling, remembering, perceiving, willing. The seemingly inert masses of physical stuff Leibniz takes to be myriads of lowly souls, imperceptible as distinct individuals, which perceive only in extremely primitive fashion. The “appetitive” aspect of awareness then explains the sequence of changes in each monad. This was one of the greatest of intellectual discoveries, far indeed from being adequately appreciated after three centuries.
Alas, the old Greek bias was still inhibiting thought. The monads did not literally act upon each other. They were only self-moving, not moved also by others. Hence, though in the Leibnizian view soul is on both sides of the mind-body relation, still the mind as dominant monad or soul does not really move the others, the bodily souls. Yet if God, as supreme soul, does not exactly move the other souls, God does, according to Leibniz, create them. For this, however, there is no provision in the general categories of the system. Not even the humblest version of power to move or create another is allotted to soul as such in Leibniz’s doctrine.
It is too little noted that in explaining away interaction among monads Leibniz was also explaining away perception and therewith one of the least dispensable of all the psychical functions. Souls interact because they perceive one another. They respond to stimuli as well as exert them. Mere “matter” is as unable to explain being moved by others as to explain moving others. The reason this was not seen, I suppose, was the push-pull image of atomistic materialism, which was an inadequate refinement of commonsense ideas of physical things. I submit that the progress of science has shown, that this is superstition. Atoms, electrons, do not push or pull, they repel or attract. And why should a lump of dead stuff move toward or away from another lump? Or consider the Pauli exclusion principle.2 The push-pull model is finally shown to be inapplicable and to derive its plausibility from the unconscious crudities of our perceptions. Visual and tactual images are now seen to be instinctively grounded pragmatic devices, not direct revelations of the basic dynamics of the world. Plato, with all his genius—indeed the Greek mind with all its genius—failed to see clearly that ability to respond to motion is as remarkable, and as beyond materialistic explanation, as ability to initiate motion.
Leibniz’s Place in the Platonic Tradition
Plato (as we saw in chapter 3) could not carry through his cosmological scheme. He could not quite see what to do about the seemingly unbesouled aspects of nature, or even about the bodies of besouled individuals. Why indeed does a soul need a body? Before Leibniz, indeed before Peirce, Bergson, and Whitehead, who learned from Leibniz, no one in all the world had any clear notion about this, although after Aristotle many philosophers perhaps thought they did. Only after Leibniz had distinguished for all time between the singular acting agents in nature and those aggregates of agents that are often taken by our gross sense perceptions as though they were themselves single agents was it possible to make progress with the genuinely Platonic program, the explanation of all process through psychical process—existing on radically different levels, and on the highest level, inclusive of the absolute Ideal or Form of Good.
Even today the alternative is materialism, just as Plato said it was. A dualism of mind and mere matter satisfies few today. For, as scientists and philosophers alike tend to feel, dualism is but a postponing of problems, a solution of none. Mere matter or else psychical process, these are the general models of explanation we have, and each has its advantage. Matter is publicly observable, since we mean by “matter” the sort of thing some instances of which act directly on those other instances that constitute our organs of perception. And the higher types of psychical process, for instance, the human, do not do this. So “methodological materialism” is still, after all these centuries, attractive. But universal psychicalism, as some who have read Leibniz thoughtfully, and not just run over some of his words, have come to realize, has ultimate and more than methodological advantages. It can easily include the sound aspects of materialism, for it can fully admit the reality and great scientific importance of the somethings that affect our senses, without giving up the assertion that these somethings, too, are psychical processes, though on a radically subhuman or other than human level.
The future of the philosophy of nature, as well as of natural theology, lies, I believe, in a modernized Platonism or reformed Leibnizianism, clarified and purified of their errors and ambiguities (or vaguenesses), the errors being largely Leibnizian, the ambiguities largely Platonic, For Plato was vaguely or indecisively right, Leibniz in part decisively, and with admirable clarity, wrong. In some ways Leibniz was the best, in some ways the worst, of the Platonists. He substituted “spiritual automatism” for Plato’s vaguer self-motion and thus missed creativity even more completely. But he did see that change as such is explicable only in psychical terms and cosmic order only by a supreme form of the psychical.
Leibniz and Spinoza on Substance and Contingency
As my colleague Edwin Allaire has astutely remarked, Spinoza and Leibniz share a common idea about substance. It is a new idea, not found in medieval philosophy: the denial of contingent predicates or accidents to a substance, The essence of a substance determines its entire career, all its concrete states or “modes.” These are “necessary modifications” of the substance.
Spinoza’s demonstration that there can be but one substance has for premise the definition of God as “absolutely infinite substance,” essentially the same unqualified denial of limitation that Leibniz also accepted from the Middle Ages. From this definition Spinoza deduces that God must necessarily possess all possibilities fully actualized.
Leibniz, however, seeing that there are incompatible possibilities, restricts divine properties to wholly positive ones (“perfections”), which, he argues, must all be mutually compatible. Not so, said Kant later, velocity in one direction is as positive as velocity in the opposite direction; but an entity cannot instantiate both at once. Spinoza would presumably say that God can have both as modes, and each is partly negative (“all determination is negation”). Leibniz would say that God is not a moving entity but still has all perfections.
What all three writers miss is that purely positive or mutually compatible perfections are highly abstract. Thus, knowledge can combine with power, goodness, and reality, and God can be uniquely excellent in all four respects. However, cognitive perfection or infallibility by itself is an empty abstraction. Concretely, God must know either that p, or that not-p; he cannot have both knowledge that p and knowledge that not-p. and whichever knowledge God has excludes the other. So there are bound to be unactualized divine cognitive possibilities, unless all truth is necessary. (And Spinoza’s proof of that position, we saw, begs the question.) Neither Spinoza nor Leibniz has shown how the denial of finitude in God is compatible with his having knowledge of the world.
In a roundabout way (here I agree with Russell) Leibniz comes to Spinoza’s denial of real contingency. The worlds that God could have (but has not) made, his goodness forbade him to make since they would have been inferior. And how “could” God have acted contrary to his goodness? The distinction that this makes the world “morally” but “not metaphysically” necessary is not impressive, since God as good exists necessarily by the ontological argument. The metaphysical necessity of God as by definition good entails the choice of the best possible world.
Leibniz and Spinoza are both entangled in a net woven long before they were born, a false rationalism that tried to derive the concrete from the abstract, becoming from being, the relative from the absolute, the contingent from the necessary. They had no clear conception of the essential creativity of becoming and defined deity as simply absolute, infinite, eternal, and necessary. Only the despised Socinians, admitting change and genuine contingency (the liberty of indeterminacy) in human decisions, and therefore in God’s concrete knowledge, opened a door into a new type of metaphysics. Three centuries were required before the philosophical profession as a whole began to see clearly what is on the other side of that door.
Notes
1. For a detailed comparison of Leibniz’s metaphysics with that of Whitehead see my essay in J. Howie and T. O. Buford, eds., Contemporary Studies in Philosophical Idealism (Cape Cod, Mass.: Claude Starck & Co., 1975), pp. 95-115.
The technical essentials of Leibniz’s metaphysics seem to me largely given in his Monadology, Discourse on Metaphysics, Correspondence with Arnauld, and New Essays on Human Understanding (commentary on Locke’s Essay), all, remarkably enough, written in French. As for the famous Theodicy, also written in French, it is an exposure of the paradoxes inherent in the traditional classical theism. Leibniz “bites the bullet,” and in the opinion of many he, or his readers, can only choke as a result.
2. That no two electrons in an atom can have the same quantum state.
Source:
Charles Hartshorne, Insights and Oversights of Great Thinkers: An Evaluation of Western Philosophy, pp. 127-135.