1) Let’s start with the punch-line:  So what is the fate of God in the modern world?

Rather troubled, I would say. Of course, I wouldn’t want to give away the plot to my book. But here’s the teaser: God underwent a major personality change in the late seventeenth century. Actually, it was kind of an existential crisis. The emergence of a scientific understanding of the world at the time made it impossible for many people to believe in the old miracle-working deity who lived on a mountain or in the clouds. So thinkers of the time asked themselves, who is God? And what does he do? Leibniz and Spinoza came up with some very radical – and radically different – answers to these questions. Depending how you look at it, you could say that God ended up on one side or the other – or he got lost in the shuffle.

2) How did you come to this particular story about the relationship between these two philosophers?

I happened to be passing through Holland in the mid-90s, and I was re-reading Spinoza. I had known about the meeting between Leibniz and Spinoza, but that was when I got the idea that it would make a great subject for a novel. Then it occurred to me that a play would be even better. Something along the lines of Copenhagen. Then I thought, why not a film? For a while, the project didn’t go anywhere.

After 9/11, and in view of the emerging theocratic tendencies in American politics, I got interested in Spinoza all over again, mainly because I see his philosophy as one of the main intellectual bulwarks against theocracy. I re-visited my old idea of a novel/play/screenplay about the meeting between Leibniz and Spinoza, and I realized that the facts of the matter were more interesting than anything I could make up.

3) Back up a minute: who are Leibniz and Spinoza?  Which one was the “Courtier,” and which one the “Heretic”?

Gottfried Wilhelm Leibniz was born in the German heartland in 1646 to a respectable but not aristocratic family. By dint of hard work and talent, he became a philosopher/scientist/inventor – and also a courtier in the halls of power, a kind of Karl Rove or I. Lewis Libby of his time. In fact, at one point he tried to get Louis XIV interested in launching a new crusade against Egypt.  He was a powerful and well-connected political figure, and he loved to dress the part: He wore fancy wigs, silk breeches, and what by our standards would probably count as too much perfume. He worked behind the scenes, writing the speeches and making the policies that kings and princes put forward.  At the end of the day, Leibniz’s metaphysics was a kind of grand apology for the established political and religious order of the seventeenth century.

Spinoza was born in Amsterdam of Portuguese-Jewish parents.  His character and circumstances were equally important to his philosophy, but he was almost the direct opposite of Leibniz. He was the heretic. When he was 24, he was expelled from the Jewish community of his birth on account of his “abominable heresies.” Later, the Christian authorities got in on the action and called him the vilest thing hell ever vomited on earth. On top of which, they pointed out, he was Jew.

There was something very rebellious in Spinoza, a fiery rejection of authority. At the same time, like some other heretics and infidels, he had the character of a true believer. He sacrificed everything in the pursuit of his philosophical vision. He was the perfect revolutionary, just as Leibniz was in a sense the consummate conservative.

4) You say that Leibniz went to visit Spinoza — secretly, and at considerable danger to the reputation and career he held precious — in order to convince Spinoza of the existence of a transcendent God.  Who do you think won that debate?

It’s not about winning and losing! But if anybody did lose the argument, then I think it was God. Seriously: Leibniz learned something very important on his visit with Spinoza, something that changed the course of his life and philosophical career – but something that he didn’t want to know. He discovered that his fancy metaphysical arguments proved the existence of a God alright, but that it was the wrong kind of God.

For Spinoza, on the other hand, the meeting would have had no effect. Leibniz at the time was young – 30 years old – extraordinarily ambitious, vulnerable, and eager to please. As a thinker, he was chaotic, conjectural, all over the place. Spinoza was the older man, and he was an architectural thinker. He had spent his life building up a single, massive, conceptual structure. The whole world was telling him he was wrong, but he never changed his mind. So Leibniz didn’t stand a chance.

5) The “wrong kind” of God?  What kind of God is “the wrong kind”?

Leibniz was heavily invested in the idea of a transcendent God – one who stands outside and before the world and creates it.  Spinoza’s idea was of an immanent God – that is, a God who is identical with the world or nature itself.  Leibniz himself was a Spinozist of sorts, but he couldn’t bring himself to believe that Spinoza’s God was divine. An immanent or Nature God, he thought, wasn’t a God at all. All of which left Leibniz – and God – in something of a pickle. He spent the rest of his life rehearsing the argument with Spinoza in his head, trying to squash his own inner Spinozist.

6) Leibniz is often remembered for being the philosopher parodied in Voltaire’s “Candide” as always insisting that “This is the best of all possible worlds.”  How could a presumably brilliant man say something so ridiculous?

Voltaire has a lot to answer for. You have to remember that this parody came out in the 1750s, forty years after Leibniz died, and Voltaire was relying on a caricature. Still, it is true that Leibniz said it. Why do philosophers make such patently bizarre claims?     Usually, because they are forced into them by some deeply held beliefs that they must at all costs maintain. In this case, Leibniz’s apparently sunny view of the world was the necessary consequence of two premises: First, that God is responsible for choosing among possible worlds; second, that God is good. From these premises, it follows necessarily that God must choose to create the best of all possible worlds.

It’s important to remember, furthermore, that another way of saying “the best possible” is “the least bad possible.” If you look at the way he behaved, you can surmise that Leibniz actually took a very dim view of the world. He thought it was a pretty cruel place; he just didn’t think there were any better worlds out there. It’s also important to note that Leibniz is talking about “worlds” here and not the things in them. It is quite possible to have nasty things in the best of all possible worlds.

8) So why didn’t Leibniz accept Spinoza’s God as “the best of all possible Gods”?

Because in Leibniz’s view Spinoza’s God was the worst of all possible Gods. Spinoza’s God, as Leibniz saw it, is just a giant machine, utterly indifferent to the wants and needs of we little people. It doesn’t think, eat, smell, or want anything; it isn’t good or bad; it just is. Spinoza thought nature was divine; Leibniz didn’t; and that was the real difference between them.

9) You portray these two abstract thinkers as incredibly concrete, physical, emotionally complicated human beings.  Would you say they both had tragic flaws?

I believe that philosophers are people, too, and philosophy is, if anything, an all-too-human affair. It’s a strange business, in a way, and you can’t really make sense of it without understanding the strangeness of the people who pursue it.

There is an element of tragedy in the stories of both thinkers.  Leibniz was almost comically vain, greedy, and ambitious. He was the kind of man who is always angling for a better job, a fancier title, and more pay. At one point, he was holding down five jobs – and didn’t bother to tell his various employers that he was moonlighting for the others. At the end of his life, his superiors finally got fed up with him, and his career took a nosedive. Not tragedy exactly, but more like farce. At the same time, there was something deeply honorable and sincere in everything Leibniz did. He really did want to make the world a better place.  Unfortunately he believed that the way to do this was to re-create the unified religious and political order of the middle ages. Leibniz’s life was a Don Quixote-style tragicomedy. He dedicated himself entirely to a project that, however virtuous in its conception, in the end amounted to nothing but vapors.

Spinoza lived and died in relatively tragic circumstances.  He lived under constant threat of persecution, and he died young of lung disease that was arguably exacerbated by the lens-grinding work he was forced to take on. His “flaw” was his arrogance, his almost clinical level of self-sufficiency. Or maybe it was his complete inability to understand how other people just couldn’t or wouldn’t see things his way. He ended up a “tragic hero” of sorts – he sacrificed himself for the sake of helping establishing the modern, liberal, secular world order in which, by and large, we live today.

10) When you say Spinoza helped establish the modern, liberal, secular world, what do you mean?

Spinoza was the first to articulate a comprehensive philosophy for modernity. He showed how it is possible to be moral in a thoroughly secular world. He showed how to destroy the ancient superstitions without succumbing to nihilism. Whether he gets the credit or not, his ideas provide the foundation for much of modern life. The American Revolution originated in ideas that can be traced directly to Spinoza.

11)  Does reading about Leibniz and Spinoza provide any lessons about how to be — or not to be — a philosopher today?

One thing you learn from studying these two philosophers is that there is no one way to be a philosopher. Philosophy for Spinoza was a way of life and a path to salvation. Philosophy for Leibniz was a field of competition and a way of improving the world. Neither approach is intrinsically the right one. Both offer eloquent testimony to the power of ideas. If there is a general lesson today in the life and work of these two seventeenth century thinkers, it’s that philosophy should matter more to us than it does. The modern world emerged from the medieval one in part thanks to the efforts of thinkers such as these two. If we hope to avoid a return to the middle ages, we’ll need to have a few philosophers around.

12) But you yourself decided not to be a philosopher, at least not in the conventional academic sense—even though you had a top-notch education in philosophy at Princeton and then Oxford.  How come you abandoned it after graduate school?  Were you one of those people who couldn’t finish a dissertation?

Many people do assume that because I haven’t pursued a career as an academic philosopher that I “abandoned” my education. But I think that, on the contrary, pursuing a career as an academic philosopher might have meant abandoning my education. I have some very serious philosophical objections to the contemporary practice of academic philosophy.  I did finish my dissertation, and it now lives in a well-earned repose somewhere in the bowels of the Bodleian Library at Oxford, where hopefully it will never ever be found.

13) Should we ask the question of what those objections might be, or would the answer be too abstract?

They wouldn’t be too abstract – they just wouldn’t be very enlightening. It is easy enough to assert that academic philosophy has tended to seal itself off from the life-world of the rest of humanity, that in the hopes of turning itself into a professional discipline it has developed a large number of ultimately meaningless projects. It’s much harder to explain why this is so, and what should be done about it. This is why people have to read my books.

14) Is it fair to describe Leibniz’s obsession with Spinoza as something like Salieri’s obsession with Mozart — the lesser talent helplessly attracted to the greater one?

It’s a colorful suggestion. But the notion that the man who invented calculus was a second-rater just isn’t accurate. On the contrary, I think that if there were some kind of global SAT test for great thinkers in history, Leibniz would come out at or very near the top. Spinoza was possibly a deeper thinker, but Leibniz was unquestionably the better all-arounder. Also, in their own time, Leibniz became something of a celebrity, a grand man of letters, a member of distinguished academic societies, whereas Spinoza was a pariah. If there is a Salieri-like aspect to the relationship, it’s about morality, not talent. I think Leibniz understood that Spinoza was simply the more honest of the two. Had Leibniz been truthful – with himself as much as with others – he would have accepted that his own philosophical views ultimately converged with those of Spinoza. At some level, Leibniz understood this – and yet he never stopped trying to deny it. So Spinoza was for him an icon of permanent moral reproach, the representative of a philosophical or moral integrity that he could never hope to achieve. Spinoza drove him crazy.

15)  What was Spinoza’s craziest idea?  What about Leibniz’s?

Leibniz had so many crazy ideas it’s hard to pick just one. The one I like best, though, is what I call his “Micro-Macro Principle,” or what he called the theory that “one is all.” The idea is that every point in the universe, no matter how small, contains a replica of the universe within itself. So, on this sheet of paper, for example, there is an infinite number of universes, complete with milky ways, stars, and radio stations. Sometimes, Leibniz got quite literal about the idea. Microscopes were new at the time, and when Anton von Leeuwenhoeck discovered bacteria, or animalcules, Leibniz immediately leaped to the conclusion that these were full-fledged animals, and that if they were in possession of their own, mini-microscopes, they would discover still smaller animalcules within animalcules, all the way down to the infinitely small, without stop.

Spinoza didn’t go for loony science, and his philosophy is less extravagant than Leibniz’s. Still, he did offer examples of a deeper kind of craziness. For example, he maintained that “men of reason”, i.e. philosophers, never disagree with each other and never have anything to fear from each other. He obviously hadn’t met Leibniz at the time of writing.