Leibniz on public health, or the values and projects of a philosopher

Portrait of Gottfried Wilhelm Leibniz

“[A]ll these things are connected and have to be directed to the same aim, which is the glory of God and the advancement of the public good by means of useful works and beautiful discoveries.” — Leibniz to Duke Johann Friedrich of Hanover, 1678

If you know a little about the philosopher Gottfried Wilhelm Leibniz (1646-1716) you might know about his large wig. A bit more, and you might know he developed the calculus, much with the notation for integration and differentiation we still use today, independently from Newton (sorry, Newton fans). Yet more, and you might know that he is one of the grandfathers of computer science, inventing binary numbers, a calculator that improved upon Pascal's, and computer code around 1700. Or you might know him as a philosopher with his wondrous metaphysics of the monads, or his view (ridiculed by Voltaire in Candide) that God created the best of all possible worlds.

It's hard to get a grip on Leibniz. He was so eclectic in his interests, so passionate about many things. Thanks to Maria Rosa Antognazza's excellent biography, Leibniz: An Intellectual Biography, I have a bit more of a sense of this very complex philosopher. One thing Antognazza brings out so well is how much Leibniz cared about philosophy, mathematics, history and all his other intellectual endeavors in pursuit of the public good. In particular, Leibniz was concerned about alleviating three great scours on humanity: poverty, illness (especially communicable diseases), and warfare.

In all his work, he aimed to work for the betterment of society and to the glory of God. Leibniz was a committed Christian who saw God as creating a pre-established harmony between people, and our free actions are in fact the working out of God's pre-ordained plans (he was thus a compatibilist about free will). Though this religious dimension was undeniably part of his outlook, he was pluralistic in that he thought Chinese society had better practical forms of living than European society, and he imagined a “commerce of light” where Europeans and Chinese people would give each other the best they had to offer.

Leibniz discusses medicine in several writings. In the way of perfecting medicine (1694), he makes a plea for the collation of health data. For example, we know that quinquina (bark of the cinchona tree, precursor of quinine) helps against malaria, but how can we use this as an effective pharmaceutical?

We could [have an] annual history of medicine drawn up for Paris and the Île-de-France, as well as for other provinces … with respect to quinquina, which has succeeded incomparably better in one year than in the other. And there should be no doubt that years similar to the preceding ones often return, where the past would be of the greatest use to decide on this matter in the future, whereas now we are reduced to learning almost always from scratch at the expense of the sick.

Leibniz foresaw that collating data and examining in systematic manner the effectiveness of this pharmaceutical would help increase its efficacy and aid malaria sufferers. Leibniz considered the infrastructure in France needed for such an endeavor and thought the police (a system that was already in rudimentary form in France in the 16th century) could do it, “A letter of a few pages would suffice for an able medical practitioner to write with regard to his city or province, addressing it, for example, to the First Doctor of the King… I imagine that the Lieutenant of Police would be delighted to assist with it, and to give encouragement to those who would like to undertake it.”

France giving the good example would, in its turn, inspire other countries to undertake such data collection. Leibniz writes,

France, by giving such a fine example of precision and curiosity, would render a very considerable service to the human race, which would not be unworthy of the glorious reign of the monarch who currently governs her. The Mithridates, the Jubas, and the Gentius, to whom we are indebted for a few medicines, would have done nothing comparable to what would be due to His Majesty if he were to take in hand the fact and cause of medicine, as he did with regard to astronomy with a success to which the efforts of the Alfonsos, Ulugh-Begs, and other similar kings could not be compared.

So, for Leibniz, taking public health seriously would add luster and glory to the rule of a monarch. In a 1671 essay, Directiones ad rem Medicam pertinentes Leibniz reiterates the importance of public health. The essay begins with praising the ancients, but then goes on to stress the importance of data collection for contemporary physicians (I could only find a Latin version of the treatise and unfortunately my Latin is bad, but you can check it for yourself here).

As he argues there, no matter how ingenious our medicinal innovations, what use is it if we forget them, or if they don't reach most of us, and if they are obliterated before they bear fruit again? (“Quid prodest detegi aliquid quod vix ad millesimum quemque pervenit et forte ante fructum rursus obliteratur.")

The limits of science are thus the limits of infrastructure. Individual brilliant minds can only do so much. But if the state were to apply itself to the systematic pursuit of medicine, including training physicians and data collection, Leibniz hoped that medicine would advance thus that people would mainly die of old age, rather than of illnesses such as “fever, pestilence, dropsy, gallstones (I think this is what is meant by “calculo”) or consumption”* People would die a natural death, or of inevitable accidents.

In that same essay, Leibniz mentions that he values microscopes above telescopes, because of the immediate applicability of telescopes to medicine.

Moral and medical matters: these are the things which ought to be valued above all. For this reason I value microscopy far more than telescopy; and if someone were to find a certain and tested cure of any disease whatsoever, he would in my judgement have accomplished something greater than if he had discovered the quadrature of the circle. (Antognazza translation, p. 99)*

Portrait of Sophia Charlotte of Hanover

Like all people in his time, Leibniz knew about the problems of communicable disease. The plague still swept through Europe in the 1660s and threw the Royal Society and other public science bodies into disarray. Infant mortality was high, and most parents could not expect to see all their children grow up. A dear friend and patron of Leibniz, Sophia Charlotte of Hanover, attended the annual carnival celebrations, caught a cold, and died after it became pneumonia in 1705 at the age of 36. Leibniz lamented her loss bitterly in this heartfelt letter to her lady-in-waiting:

I do not weep, I do not complain, but I do not know where I am. The loss of the queen seems like a dream, but when I awake from my slumber I find it only too real. Your grief in Hanover does not surpass mine in anything, except that you have more vivid feelings and have been struck from close range by the misfortune that we share. This is what encourages me to write to you and to beg you to moderate your sorrow, if you can, so that it does not harm you. It is not by dark despair that you honour the memory of one of the most accomplished princesses in the world. It is by imitating her that we can do so, and the learned world will do the same. This letter is more philosophical than my heart, but I am the master of my letter, and I am not in a fit state to follow my own advice exactly, though it is not less reasonable on that account.

This was not the first loss Leibniz suffered (his patrons had an annoying habit of dying at inconvenient moments), and such losses were universal. But Leibniz had the vision to think about how, with public infrastructure, investment in science, and data collection, we would eventually be able to reduce this tragedy and make a healthier population possible. Unfortunately, Leibniz's patrons showed little interest in these pursuits of public health. Neither were they interested in his proposals for a kind of proto-EU, or for a transnational scientific society, or other things that furthered the public good.

Here it's interesting to note that Leibniz worked for various courts, mostly in Hanover, as a deliberate decision. He could have gone into academia, as he was offered a professorship after he received his doctorate in law, but he declined it. I am wondering to what extent this was because Leibniz hoped to have more indirect political influence as a courtier. Unfortunately for Leibniz, his patrons by and large were not interested in his vision, forcing him to work on things to their narrow benefit such as genealogical investigations that would help them solidify political claims.

Still, though most of Leibniz's bigger projects failed (in contrast to his individual pursuits such as calculus, binary numbers, which were highly successful) because he could not find the critical mass of people to rally to his cause, I think there's something very noble and beautiful in at least trying.

We are up against huge obstacles. The scours of humanity that Leibniz felt we are able to eradicate, warfare, poverty, and disease are still around. It is only by many people pushing that, eventually, we will succeed in defeating them.

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*original: Neque enim dubitandum est muitos homines facile negotio servari posse, quales ego omnes esse arbitror, qui febri, qui peste, qui hydrope, qui calculo, qui phthisi, qui vitio aliquo humorum moriuntur. Nam in quibus ruptum est aliquid, aut quibus viscera, vivendi tractu velut detrita sunt, in eorum ratio alia est. Denique putem brevi temporis spatio per medicinam effici posse, ut homines fere non nisi morte naturali, aut saltem infortuniis inevitabilibus (qualia sunt vulnera letalia, lapsus, rupturae viscerum aliaque id genus) moriantur.

*original: Moralia et medicinaria haec sunt quae unice aestimari debent. quare Microscopia longe magis quam Telescopia aestimo, et si quis morbi cuiuscunque certam explora- tamque curationem invenerit, eum ego majoris faciendum arbitror, quam si quadraturam circuli invenisset