Justified True Belief

(●) The last man who tried to hold every science at once, and the one who gave the problem of evil its name. + Ask most people what a philosopher does all day and the answer will involve a desk. Leibniz had a desk, in a ducal library in Hanover, but he also designed pumps for silver mines, drew up a scheme to steer a French war away from Germany, built a machine that could multiply, invented the notation for the calculus that every engineering student still uses, wrote a family history for his employers, kept up letters with something like eleven hundred correspondents across Europe, and founded an academy of sciences in Berlin. He is the last figure of whom it can be said without embarrassment that he worked at the front edge of nearly every subject there was. For Christian readers he matters for a narrower reason than any of that. Leibniz took the question that will not go away, why there is anything at all rather than nothing, and pressed it into an argument for God that philosophers are still repairing and still using three centuries later. Then he wrote the book that named the hardest problem on the other side of the ledger. The word theodicy is his, built out of the Greek theos, God, and dikê, justice, and it means an attempt to show that a good and almighty God can be squared with a world like this one. Here is the fact to keep hold of. Plato published about thirty works and lost none of them. Leibniz published exactly one book of philosophy in seventy years, the Theodicy of 1710, and left behind as many as two hundred thousand sheets of paper. The scholarly edition of that hoard was begun in 1923, has about half the corpus in print, and is not due to finish until the middle of this century.

(●) 1646 AD: He grew up in the library his dead father left him, and had a doctorate in law before he was twenty-one. + Gottfried Wilhelm Leibniz was born in Leipzig on 1 July 1646, a little over two years before the treaties that ended the Thirty Years’ War. His father Friedrich was a professor of moral philosophy at the university there, and he died when the boy was six. What he left behind was a room full of books, most of them in Latin, and the family let the child into it. He taught himself the language out of those books, working through the Roman historians with the woodcuts in an illustrated Livy for a crutch, and by his early teens he was reading the church fathers and the scholastics, the medieval theologians who had argued Christian doctrine into system. That last detail matters more than it looks. Almost every other philosopher of his century treated scholastic thought as rubble to be cleared; Leibniz spent his life insisting that the medievals had been right about a great deal and that the moderns had thrown out good work with the bad. He entered the University of Leipzig at fourteen and took a master’s degree in philosophy at seventeen, in February 1664. When he came to the doctorate in law, Leipzig turned him down. The usual account is that the faculty promoted only twelve candidates a year and he was the youngest man in the queue; a second story, repeated by his early biographers, has the dean’s wife talking her husband into arguing against him, for a reason nobody has ever been able to give. So he rode to the small university of Altdorf near Nuremberg, defended a thesis on hard cases in law on 15 November 1666, and had the degree in hand by February. Altdorf offered him a professor’s chair on the spot, and he said no. He had, he told them, very different things in view.

(●) 1667 AD: He turned his back on the university and went to work for a prince instead. + On the road home he fell in with Johann Christian von Boineburg, a baron who had converted to Catholicism and had been first minister to the Elector of Mainz, one of the princes who chose the Holy Roman Emperor. Boineburg took to the young man at once and found him work. For the next five years Leibniz was a lawyer, a diplomat, and a house intellectual, revising the tangle of German law into something a court could actually use and writing on demand about anything his patron was arguing over that month. Some of what he wrote in those years was apologetics in the plain sense. Boineburg was a convert with Lutheran friends, which made his household an awkward and interesting place, and Leibniz drafted pieces on the Trinity and the Eucharist meant to show that the two confessions, meaning the two churches with their rival statements of faith, were not as far apart as the shouting suggested. The habit stuck. He was still working at the reunion of divided Christians thirty years later, when nobody had asked him to and nothing had come of it yet. The strangest project of the Mainz years was a memorandum urging Louis XIV to conquer Egypt, and the point of it was never Egypt at all. France was arming, everyone in Germany knew which way that army would go once it moved, and the whole scheme was an attempt to point it somewhere far away instead. Leibniz was the man chosen to carry the proposal to Paris, which is how a young German lawyer came to be sent to the greatest court in Europe carrying a plan for redirecting a war. He never got his audience.

(●) 1672 AD: A diplomatic errand to Paris turned into four years of mathematics, and by 1675 he had the calculus. + Paris in 1672 was where mathematics was happening, and Leibniz arrived not knowing much of it. His training had been in law and scholastic philosophy. What saved him was Christiaan Huygens, the Dutch physicist then living in Paris, who took his measure by setting him a puzzle. Start with the triangular numbers, which are simply the counts of dots you can lay out in a neat triangle: one dot, then three, then six, then ten, and on up. Now turn each of them upside down into a fraction and add the fractions together, one, then a third, then a sixth, then a tenth, going on forever. What does that endless sum come to? Leibniz came back with the answer, which is two, having noticed that each term can be rewritten as the difference between two simpler fractions, so that nearly everything cancels against its neighbour down the line and only the front of the sum is left standing. Huygens saw what he was dealing with and handed him a reading list, and Leibniz went through it the way he had gone through his father’s library. He had also been building a machine. Pascal’s calculator could add and subtract; Leibniz wanted one that could multiply and divide as well, and the stepped drum he designed for it was still turning up in commercial calculators two centuries later. He carried an unfinished model to London in 1673 and showed it to the Royal Society, where it did not quite work. They elected him a fellow that April anyway. The mathematics came in a rush in the autumn of 1675. On 29 October he wrote a long thin S for a sum, from the Latin summa, and the integral sign has looked like that ever since; within a fortnight he had the d for a difference and the rules for handling both. Then he sat on all of it for nine years before publishing a line, a delay that would cost him more at the end of his life than he could possibly have guessed at the time. In the meantime Boineburg had died and the Elector after him, and by 1676 the most inventive man in Europe was out of a job.

(●) 1676 AD: He took a librarian’s post at Hanover and served the same family for forty years. + The offer came from Duke Johann Friedrich of Brunswick-Lüneburg: librarian and court counsellor at Hanover, a good salary and a small town. Leibniz took the long way there, through London and Holland, and in November 1676 he spent several days in The Hague with Baruch Spinoza, who let him read parts of the unpublished Ethics. He argued with that book for the rest of his life and was careful, afterwards, about who knew he had been in the room. Hanover was where he stayed. Three dukes in succession employed him, the last of whom became George I of Great Britain, and the work was whatever a versatile servant could be given: cataloguing books, drafting legal opinions, advising on coinage, running the family archive. From 1680 he spent six years and something like thirty journeys trying to drain the silver mines of the Harz mountains with windmill-driven pumps. The wind was unreliable, the mine officials were hostile, and the project failed completely. He was also commissioned to write the history of the ducal house, which sent him off in November 1687 on a hunt through the archives of Germany, Austria and Italy that kept him away for two and a half years and turned into the work that ate his old age. He never finished it. He was better at founding things than at finishing them. In 1700, at the urging of Sophie Charlotte, Electress of Brandenburg and within months Queen of Prussia, one of the two royal women who were his closest philosophical friends, he founded the society of sciences in Berlin that grew into the Prussian Academy, and served as its first president. He pressed similar plans on Vienna, Dresden and St Petersburg, and met Peter the Great three times to argue for the Russian one.

(●) 1686 AD: In a single winter he set down his whole philosophy and sent it to the most formidable theologian in France. + Early in 1686, away in the Harz on mine business, Leibniz wrote out thirty-seven short articles covering God, substance, freedom, miracles and the nature of a person. He told Ernst von Hessen-Rheinfels about it in February. Ernst was a landgrave, which is to say a German prince with a territory of his own, and he liked nothing better than carrying a theological argument between people who would not write to each other directly. Having been somewhere where he had nothing to do for several days, Leibniz wrote, he had written a short discourse on metaphysics, and he would be delighted to have Arnauld’s opinion of it. The little book had no title in his lifetime; posterity calls it the Discourse on Metaphysics, and it is the clearest statement of his mature thought. He did not publish it. What he did instead was send a list of the article headings to Antoine Arnauld, by way of the Landgrave, who could be trusted to pass it on. Arnauld was the great theologian of the Jansenists, the strict Catholic party that took Augustine’s side on grace and human helplessness and was harried by Rome and the French crown for years on account of it, and he was one of the men who had cross-examined Descartes. Nobody sent Arnauld a manuscript for encouragement. Arnauld read the thirteenth heading, saw in it the conclusion that everything that ever happens to a person is already contained in the idea God has of that person, and wrote back that such a doctrine would destroy human freedom outright. The correspondence that followed ran for four years and is the best thing either man wrote. It cost Leibniz nothing he was not glad to pay: he had asked for Arnauld’s opinion himself, and he got it. The same years carried the labour he cared most about. With the Catholic bishop Cristóbal de Rojas y Spinola in the 1680s, and with Bossuet, the court preacher of Louis XIV, in the 1690s, he worked at terms on which Rome and the Lutherans might be reconciled, and later with Daniel Ernst Jablonski of Berlin at reuniting the Lutherans with the Reformed, meaning the churches of the Calvinist tradition. Every one of those negotiations failed. He kept at them for thirty years anyway, which tells you something about the man that no summary of his metaphysics will.

(●) 1710 AD: The Theodicy appeared, the only book of philosophy he ever brought to press. + The book grew out of conversations at the Berlin court with Sophie Charlotte, who kept pushing him to answer Pierre Bayle. Bayle was a French Protestant exile whose enormous Historical and Critical Dictionary had argued, with maddening politeness, that the existence of evil cannot be reconciled with a good and almighty God by reason at all, and that a Christian must simply believe it in the teeth of the argument. Leibniz thought that concession fatal, and he set out to show that faith and reason are not at war on this question. The full title says what the book is: Essays of Theodicy on the Goodness of God, the Freedom of Man and the Origin of Evil. It runs to a preface, a long preliminary dissertation on the agreement of faith with reason, three parts, and an appendix that boils the whole case down into numbered syllogisms so that an objector can see exactly which line to attack. The argument is that God is not the author of evil but permits it; that evil comes in three kinds, the mere limitation of any created thing, the suffering of creatures, and the sin of wills; and that the world containing them is nevertheless the best whole that could have been made. Sophie Charlotte died in 1705, five years too early to read the book she had argued him into writing. It appeared in Amsterdam in 1710, in French, the year its author turned sixty-four, and it did for him what none of his mathematics ever had: it made him famous across Europe, and famous as a man defending the goodness of God rather than as the man with the useful notation.

(●) 1716 AD: He died at seventy, and one man walked behind the coffin. + The last years were bitter. The quarrel with Newton over who had invented the calculus had been simmering since 1699, and in 1712 the Royal Society appointed a committee to settle it. The committee found for Newton. What nobody outside knew was that Newton, as president of the Society, had chosen the members, and that the anonymous review of their report which spread the verdict across Europe was written by Newton himself. Historians now hold that the two men reached the calculus independently, that Newton had it first and kept it in a drawer, that Leibniz published first, and that it is Leibniz’s notation the world uses. Then his employer left him behind. In 1714 Georg Ludwig of Hanover became George I of Great Britain and moved to London, taking his court with him. Leibniz asked to come and was told to stay in Hanover and finish the family history, which after thirty years still stopped somewhere in the eleventh century. He spent his last year writing five long letters to Samuel Clarke in London, arguing about God and space with Newton at Clarke’s elbow, and died in the middle of the exchange on 14 November 1716. He was buried in the Neustädter Kirche in Hanover. His secretary, Johann Georg von Eckhart, was the only mourner from the court; George I was in the neighbourhood and did not attend. A Scot who was in Hanover at the time, John Ker of Kersland, wrote in his memoirs that Leibniz was buried more like a robber than like what he really was, the ornament of his country. The Royal Society, which had elected him a fellow forty-three years before, said nothing at all, and neither did the Berlin academy he had founded. The Paris Academy of Sciences, of which he was a foreign member, had Fontenelle read a formal eulogy the following year, and for most of the eighteenth century that eulogy was the fairest thing anyone had said about him in public.

What He Taught

(T1) Nothing is without a reason, and the reason for the world cannot lie inside the world. + Your car will not start. You do not conclude that it just did not, for no reason; you open the bonnet, or you call someone who will. Nobody actually lives as though things happen for no reason whatever, and Leibniz simply took that refusal seriously and gave it a name. He called it the principle of sufficient reason: for anything that is the case, there is a reason why it is that way rather than some other way, whether or not anyone happens to know it. Beside it he set a second principle, the principle of contradiction, which is just the rule that nothing can both be and not be. Those two, he said, are what all our reasoning runs on. Now apply the first one to the world. Everything in it is what philosophers call contingent, meaning it might have been otherwise: this book, this planet, this galaxy, none of them had to exist. Ask why any of them is here and the answer sends you to something earlier, which is contingent too, and so sends you further back. Leibniz’s point is that the sending never ends, and that lengthening the chain never pays the debt. He put it with a homely example of his own. Suppose a geometry book has been copied from an earlier copy, and that one from an earlier one, back forever. You have explained the wear on the pages and the copyist’s errors. You have not explained why there is a book about triangles in the world at all. So the sufficient reason for the whole series, if there is one at all, has to lie outside the series, in something that is not contingent: a necessary being, meaning one that carries the reason for its own existence inside itself instead of borrowing it from something earlier. That is what Leibniz means when he says the argument ends in God. That conclusion is real, and it is also limited, in two ways worth being plain about. First, the argument never asks whether the universe had a beginning, which makes it a different animal from the arguments that turn on a first moment; on Leibniz’s reasoning a universe that had always existed would stand just as much in need of explaining as a young one, because age is not an explanation. Second, what arrives at the end of it is a necessary ground of everything, and that is a long way from a Father who speaks, forgives, and comes looking for people. Leibniz knew that as well as anyone. His whole system was an attempt to walk from the one to the other.

(Q) "Why does something exist rather than nothing? For ‘nothing’ is simpler and easier than ‘something.’" + Source: Leibniz, Principles of Nature and Grace, section 7 (Latta translation). Written in 1714, two years before he died, for Prince Eugene of Savoy. Leibniz has just finished describing living things as a physicist would, and announces that it is time to rise to metaphysics, laying down the principle of sufficient reason as he goes. This, he says, is the first question we are entitled to put once that principle is in hand, and the next section argues that the answer cannot be found anywhere in the run of contingent things (T1).

(T2) Of all the worlds God could have made, he chose the best one. + Picture an architect with one plot of ground and an infinite portfolio of drawings. He can build any of them, but only one, and he is both perfectly wise and perfectly good. Which does he build? Leibniz thought there was only one answer available, and that it followed from the principle of sufficient reason rather than from piety. God knows every possible world, meaning every complete and self-consistent way that things could have gone from beginning to end, not a planet somewhere but a whole history. Only one can be made actual. A being who does nothing without a reason must have had a reason for choosing that one, and the only reason a perfect being could have is that it is the best. Anyone who has sat in a hospital corridor at three in the morning will want to interrupt at this point and say: then look at this, and tell me it is the best. The claim is misread more often than almost anything else in philosophy, and the misreading is close enough to the truth to sting. It does not say that every event is good, or that a child’s death is secretly a blessing, or that things could not be better here on this street this afternoon. What it says is that the total package, every event together with everything each event makes possible, all of it taken as one, is the best total package there could be. Leibniz reaches for a painting with dark patches in it, and for music that uses dissonance, the sour chord that makes the resolution mean something: pull out the shadow and you do not get a better picture, you get a worse one. Whether a comparison drawn from paintings and chords can carry the weight of real suffering is the objection the book gets, and it is a fair one. For a Christian reader the doctrine sits close to something Scripture does say, that God works all things together for good for those who love him (Romans 8:28), and then goes further than Scripture in claiming we can know that the sum is optimal. That extra step is where most of the arguing has happened ever since.

(Q) "Thus the actual existence of the best that wisdom makes known to God is due to this, that His goodness makes Him choose it, and His power makes Him produce it." + Source: Leibniz, Monadology, section 55 (Latta translation). The last step of a three-step argument, and the steps are short enough to follow one after another. Section 53 says that there is an infinite number of possible universes in the ideas of God, that only one of them can be made actual, and that there must therefore be a sufficient reason for the choice. Section 54 says the reason can only be the degrees of perfection those worlds possess. Section 55 then assigns the parts, wisdom to see the best, goodness to want it, and power to bring it about (T2).

(T3) Good is not good because God commands it; God commands it because it is good. + There are two ways a father can answer a child who asks why lying is wrong. He can give a reason, or he can say "because I said so." Both settle the question, but only one of them tells the child anything about lying. The same fork appears in theology, and Leibniz took a side with unusual heat. The view he was attacking is called voluntarism, from the Latin for will: the position that right and wrong are fixed by God’s bare choice, so that if he had commanded cruelty instead, cruelty would have been righteous. It is not a fringe view. Late medieval thinkers such as William of Ockham argued for it precisely to keep anything at all from standing over God, and the worry behind it is a real one. Leibniz answered that the cure kills the patient. If God would be exactly as praiseworthy for commanding the opposite, then calling him good says nothing, and praise becomes flattery of the strongest party. He noticed that this is the ancient definition of tyranny: justice as whatever pleases the one with the power. His own solution was to locate the standard in God’s understanding rather than in God’s will. The eternal truths, mathematical and moral alike, follow from what God is, and they no more depend on his decisions than his own essence does. Nothing is thereby placed above God, because the standard is not a rule God consults; it is God’s own nature, and his commands express it. That is the classic Christian answer to the old dilemma Socrates put to Euthyphro, whether the holy is holy because the gods love it or loved because it is holy. The line of Scripture Leibniz is closest to is the one that praises God’s ways as being just rather than as making justice: "The Rock, his work is perfect, for all his ways are justice" (Deuteronomy 32:4). Christians have divided over how much of the standard belongs to God’s will and how much to his nature, and the argument is old and still live, but the version Leibniz gave is the one most often taught today.

(Q) "In saying, therefore, that things are not good according to any standard of goodness, but simply by the will of God, it seems to me that one destroys, without realizing it, all the love of God and all his glory; for why praise him for what he has done, if he would be equally praiseworthy in doing the contrary?" + Source: Leibniz, Discourse on Metaphysics, article 2 (Montgomery translation). The article is headed "Against those who hold that there is in the works of God no goodness, or that the principles of goodness and beauty are arbitrary." Leibniz goes on to ask where God’s justice and wisdom would be if arbitrary will took the place of reasonableness, and to say that the eternal truths follow from God’s understanding, which no more depends on his will than his essence does (T3).

(T4) Walk into a thinking machine and you will find no thought inside it. + This is one of Leibniz’s most quoted paragraphs, and the picture in it is his own. Imagine a machine built so that it thinks and feels and perceives. Now enlarge it, keeping every proportion the same, until it is the size of a mill, and walk in through the door. You will see parts pushing on parts. Rods, gears, levers, one thing shoving the next. What you will not find anywhere on the floor is the seeing of red, or the smell of bread, or the ache of missing someone. You can account for every motion in the building and you will not have accounted for a single perception. His conclusion is stated in his own vocabulary, which needs unpacking. Perception, he says, is "inexplicable on mechanical grounds, that is to say, by means of figures and motions." Figures and motions means shapes and movements, which is all that a machine, on the physics of his day or ours, is made of. So whatever else a perceiving thing is, it is not simply an arrangement of pieces in motion, and Leibniz drew from this that perception must belong to what he called simple substances: things with no parts at all, and therefore nothing to walk among. He named them monads, and it is from that word that the Monadology gets its title. The rest of his metaphysics on this point is his alone and few have followed him there. The mill has done much better. Three centuries later the same problem is discussed under the name of the hard problem of consciousness, the difficulty of explaining why any amount of physical processing should be accompanied by an inner life at all, and philosophers on both sides of the question still reach for the mill to state it. The argument does not by itself demonstrate a soul, and it should not be sold as though it did. What it does is put a hard and durable question to the claim that a human being is nothing but matter well arranged.

(Q) "And supposing there were a machine, so constructed as to think, feel, and have perception, it might be conceived as increased in size, while keeping the same proportions, so that one might go into it as into a mill. That being so, we should, on examining its interior, find only parts which work one upon another, and never anything by which to explain a perception." + Source: Leibniz, Monadology, section 17 (Latta translation). The Monadology is ninety numbered paragraphs written in 1714 and never published in his lifetime, in which the whole system is compressed into a few pages. Leibniz used the mill more than once in his letters and essays; this is the version that everybody quotes (T4).

(T5) A world made well does not need mending, and a maker who keeps mending his work is a poor workman. + In November 1715 Leibniz wrote to Caroline, Princess of Wales, who had known him at Hanover, to say that natural religion was decaying in England and that Newton’s philosophy was part of the reason. Natural religion is what a person can come to know of God from the world itself, without a Bible open in front of him, and in that century it was the common ground on which believers argued with unbelievers. Caroline showed the letter to Samuel Clarke, Newton’s friend and the best philosophical mind among his followers, and the two men exchanged five papers each before Leibniz died. It is the last thing he wrote, and one of the great debates in the history of thought. The complaint that started it was about God’s workmanship. Newton had suggested in print that the mutual pulls of planets and comets would slowly accumulate irregularities in the solar system until it needed correction. To Leibniz that was an insult dressed as reverence. A clockmaker who has to come back and reset his clock is a worse clockmaker, not a better one, and a God who must periodically repair the world is being praised for the sort of intervention that shows up bad design. One old word in the quotation trips modern readers: when Leibniz says God "wants" to wind up his watch, "wants" is the English of 1717 for "needs." Neither man should be misheard here. Leibniz is not denying providence or miracles, both of which he affirmed and neither of which he was willing to give up; what he denies is that God’s ordinary upkeep of the world takes the form of repairs to a faulty machine. And Clarke had a serious answer of his own. A God who continually governs the world, he said, is nearer to it and greater than one whose machine runs along without him, and Leibniz’s beautifully tidy universe was a short step from the deist’s absent landlord, the God who builds the world, winds it up, and goes away for good. Both men were defending God’s honour, and what they disagreed about was where it lay. Out of the same letters came the other quarrel that outlived them, over whether space and time are real containers that God made or simply the order of relations among things. Leibniz argued for relations, on his usual principle: if space were a container, there could be no sufficient reason for God to have put the whole world here rather than three feet to the left.

(Q) "According to their doctrine, God Almighty wants to wind up his watch from time to time: otherwise it would cease to move. He had not, it seems, sufficient foresight to make it a perpetual motion." + Source: Leibniz’s First Paper to Samuel Clarke, section 4, in A Collection of Papers, which passed between the late Learned Mr. Leibnitz, and Dr. Clarke (Clarke’s own English version, London, 1717). The sentence that follows is harder still: the machine of God’s making is so imperfect, on this account, that he must clean it now and then and even mend it, as a clockmaker mends his work, and must therefore be so much the more unskilful a workman as he is the oftener obliged to set it right (T5).

(Q) "This City of God, this truly universal monarchy, is a moral world in the natural world, and is the most exalted and most divine among the works of God." + Source: Leibniz, Monadology, section 86 (Latta translation). Where the system ends. Having spent eighty-five paragraphs on substance, perception and the physical order, Leibniz closes with the claim that all minds together make up a community under God, and that God stands to the natural world as an architect and to this community as a monarch. The phrase is Augustine’s, and the borrowing is deliberate.

What Christian Thinkers Made of Him

(†) He gave the problem of evil its name, and the answers given since are still built on his frame. + The material was ancient. Augustine had written on the origin of evil, Boethius on providence from a prison cell, Aquinas on why a good God permits defect. What did not exist before 1710 was a word for the enterprise, and Leibniz supplied it. A theodicy, in the sense his title created, is an attempted justification of God’s ways in the face of the world’s evil, and the distinctions he drew in making one are the ones the discussion still uses: that God wills the good and only permits the evil, and that evil comes in the three kinds of limitation, suffering and sin. The most famous response was a joke. In 1755 an earthquake and the sea that followed it destroyed Lisbon on All Saints’ Day and killed tens of thousands of people, many of them in church. Four years later Voltaire published Candide, in which the tutor Dr Pangloss surveys catastrophe after catastrophe and insists that all is for the best in the best of all possible worlds. It is superb, it has never gone out of print, and it is not quite aimed at Leibniz, whose claim was about the whole and not about each disaster in it. But the caricature did what caricatures do, and for two centuries most educated readers knew the doctrine only through Pangloss. The twentieth century took the question up in earnest again. J. L. Mackie argued that the existence of evil makes belief in an omnipotent good God positively contradictory. Alvin Plantinga answered him with the free will defense, and took some care to distinguish a defense, which only shows that the charge of contradiction fails, from a theodicy, which claims to say why God actually permits what he permits. Along the way Plantinga argued that Leibniz had made a specific mistake in assuming God could create any possible world he pleased, a mistake he was cheerful enough to label Leibniz’s lapse. John Hick’s Evil and the God of Love sorted the whole tradition into types working against the same background. Nobody working on the problem today, believer or critic, is working without tools Leibniz put on the bench.

(†) The argument from contingency he sharpened is still in service three centuries later. + Samuel Clarke, before he was Leibniz’s opponent, was his unwitting ally. Clarke’s Boyle Lectures of 1704, an annual course of sermons endowed by the chemist Robert Boyle for the defence of the Christian faith against unbelief, and published the next year as A Demonstration of the Being and Attributes of God, put a version of the argument from contingency into English in the most rigorous form it had yet received, and it became a fixture of English natural theology for a century. Then came Kant, who took it seriously enough to give it the name it still carries, the cosmological proof, and to spend a chapter of the Critique of Pure Reason dismantling it. His objection was that the argument cannot get from a necessary being to God without quietly smuggling in the ontological argument, the quite different attempt to squeeze God’s existence out of the bare idea of a most perfect being, which Kant had already rejected. For a long time that was thought to be the end of the matter. It was not. The argument came back in the second half of the twentieth century, first in a much-reprinted textbook restatement by Richard Taylor, then in serious rebuilding by Richard Swinburne, Robert Adams, Timothy O’Connor and Alexander Pruss, and in the popular apologetics of William Lane Craig, whose version is called the Leibnizian cosmological argument to its face. The live dispute has moved to where Leibniz put the weight: whether the principle of sufficient reason holds for the universe as a whole, and whether it proves too much by making everything that happens necessary. Peter van Inwagen has pressed that second worry hard, and answering it is now the price of admission. What is not in dispute is whose argument is being argued about.

(†) Through Christian Wolff his system became the school philosophy of Protestant Germany, and Kant grew up inside it. + Leibniz left no school and no summary. Christian Wolff, a mathematician turned philosopher at Halle, supplied both, and did it in German as well as Latin, which meant that ordinary students could read it. What he taught was tidier than Leibniz and less interesting, and for two generations the Lutheran universities taught it as the philosophy, under the name the Leibnizian-Wolffian system. It was not a quiet reign. Halle was also the headquarters of the Pietists, the Lutheran renewal movement that put a converted heart and a changed life ahead of correct doctrine and had little patience for professors proving things about God, and they thought Wolff’s demonstrations left no room for grace and turned God’s decisions into a sum. In 1723 they persuaded King Frederick William I to give Wolff forty-eight hours to leave Prussia on pain of hanging. He went to Marburg, became more famous than ever, and was brought back in triumph by Frederick the Great in 1740. The episode is a fair warning about what happens when a devotional tradition and a rationalist one are handed the same doctrine of providence. The most important thing the school produced was the man who broke it. Immanuel Kant was raised on Wolff’s textbooks, and in 1765 the answer to Locke that had sat in a drawer for sixty years finally came into print: Leibniz’s own New Essays, far subtler than the system built in his name. Kant read it in 1769 and argued with Leibniz for the rest of his working life, and the critical philosophy he went on to build, so called because it begins with a critique of reason itself, asking what the mind brings to experience and how far reason can reach without it, took the Leibnizian-Wolffian account of space, time and knowledge as its chief target. Leibniz thus shaped modern philosophy twice: once through the books he published, and once, half a century after his death, through the ones he did not.

(†) Where his own account strains: an evil that starts in finitude, and a God who cannot do other than best. + Leibniz was a Lutheran who defended the Trinity, the incarnation and the resurrection against the sceptics of his day, and the hard questions his own books invite come from readers who wanted him to succeed rather than from his enemies. Three of them have never gone away. - Evil that begins in being finite. Asked where evil comes from if everything comes from God, the Theodicy answers that its root lies in the creature’s own nature, since "there is an original imperfection in the creature before sin, because the creature is limited in its essence" (section 20, Huggard translation). Scripture puts the root somewhere else. Sin enters through a will that refuses, and Paul dates the wound to a choice: "Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned" (Romans 5:12). James is blunt that God tempts no one, and that "each person is tempted when he is lured and enticed by his own desire" (James 1:14). Leibniz would reply that limitation only makes evil possible and never makes it actual, which is a real answer. It has not satisfied his readers, then or since. - A maker who must make the best. If perfect goodness and perfect wisdom oblige God to choose the best world, in what sense did he choose freely? Leibniz’s answer is a distinction: the necessity is moral, not metaphysical, so that God could do otherwise but would not (Theodicy, Abridgement of the Argument, reply to the eighth objection). Scripture speaks of creation as the free act of a will that owed nothing, "by your will they existed and were created" (Revelation 4:11), and of salvation the same way: "For by grace you have been saved through faith. And this is not your own doing; it is the gift of God" (Ephesians 2:8). Whether "could but would not" preserves that freedom is precisely the question, and three centuries have not settled it. - A confidence Scripture does not underwrite. Leibniz claimed to show that no better world was possible. The Bible never suggests that a creature can audit the books. "Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways!" (Romans 11:33). It is possible to hold everything he wanted to hold, that God is good, that evil is permitted rather than authored, and that the end will justify the road, without claiming to have seen the ledger. None of this is a reason to put him down. He was trying to keep two things together that most of his contemporaries were pulling apart, a God who is genuinely good by a standard we can recognise and a world that is genuinely as bad as it looks, and he did it in public, with his working shown, so that anyone could find the weak joint. That is a rarer kind of courage than it sounds.