The Tanner Library at the University of Michigan houses countless volumes covering the whole history of western philosophy. The tables are usually strewn with books opened to important pages and the chairs are filled with students quietly puzzling over difficult passages. A little more than 20 years ago I was one of those students, an excited, young, fresh college graduate. Shortly after starting graduate school at Michigan, where I was hoping to earn a PhD in philosophy, I fell in love with the amazingly intricate thought of Immanuel Kant. A late Enlightenment thinker who championed the French Revolution from his perch in far eastern Prussia, Kant was notoriously difficult for students to understand. That was part of the allure.

Trying to be on the cutting edge, I went a step further: I didn’t just read his most influential works, like the “Critique of Pure Reason,” but Kant’s earlier pieces from the mid-18th century, written before he became famous. And it was while reading one of those early works that I came across a reference to someone named the Marquise Du Châtelet. It stopped me in my tracks.

I double-checked to make sure that it didn’t say “Marquis” instead. I had enough French to know the significance of that little “e”: Kant was referencing a female philosopher.

Back then, one could receive an entire college education in philosophy without reading a single text written by a woman. In fact, one could take a dozen courses without even hearing a woman’s name mentioned. And so I read Kant’s pages-long description of Madame Du Châtelet’s work, I was stunned. Who is this French woman, obviously some kind of aristocrat, whom Kant is discussing? But soon, a more depressing thought overcame me: Why haven’t any of my teachers ever mentioned Du Châtelet? For that matter, why have they never mentioned any woman who published philosophical works during the 17th or 18th centuries? They must have been pretty obscure, I thought.

Just as quickly as I formed that thought, an obvious rebuttal occurred to me. Here I was, a young student without any specialized knowledge, and I found not just a reference to a French woman doing philosophy in the 18th century, but a long discussion of her ideas. And what’s more, I didn’t find the reference in a forgotten book written by some obscure thinker. I found it in Immanuel Kant, perhaps the most famous Enlightenment philosopher of them all. But if Madame Du Châtelet was famous enough that her ideas made their way from Paris to the far reaches of eastern Prussia during her lifetime, what happened to them afterwards?

I am a bit ashamed to admit that back in graduate school, despite the impression that this episode made on my young mind, I didn’t run to my advisers and demand an answer. I didn’t drop everything and dedicate myself to learning about women like the Marquise. That is the stuff of Hollywood movies. Perhaps all too predictably, I kept this experience to myself and went back to my studies; eventually, I wrote a whole dissertation on Kant. But I never forgot about that day in Tanner Library. And my early shame was eventually met with a bit of redemption later. Once I felt more secure in my career, I went back to my earlier question: What had happened to philosophers like her?

It won’t be surprising to learn that I quickly found a treasure trove of feminist work from the 1980s and 1990s that answered my question.

Perhaps the most systematic and compelling answer came from a now-famous paper by the philosopher Eileen O’Neill, “Disappearing Ink.” The title of O’Neill’s paper, which extensively chronicles the many contributions of women to early modern philosophy, says it all. It wasn’t that women were excluded from centers of learning, such as universities and scientific academies, and therefore never had a chance to contribute to the development of philosophy during this time in European history.

On the contrary, as Kant’s discussion of Madame Du Châtelet indicates, they did in fact contribute a great deal. Indeed, O’Neill discusses not only Madame Du Châtelet in France, but also Mary Astell, Margaret Cavendish, and Anne Conway in England, Laura Bassi in Italy, and Anne Maria von Schürmann in Prussia.

But the various publications by these figures — from plays to poems to letters to lengthy philosophical treatises — eventually disappeared from the historical record.

But by the time a number of influential male German scholars from the 19th century, such as Kuno Fischer and Ernst Cassirer, wrote their magisterial works on the history of early modern philosophy in Europe, the contributions of these women were long since forgotten. Amazingly, the list of figures canonized in the 19th century — from Descartes and Leibniz to Locke and Kant — had changed little in the hundred years that past before I went to graduate school. Not a single woman had been added.

But things have changed. Today, there is a remarkable scholarly trend involving scholars throughout the world of philosophy that is slowly righting this historical wrong. Building on the work of feminist pioneers like O’Neill, there is now a robust reassessment of the history of philosophy in early modern Europe, stretching all the way from the proto-feminist treatises written by women in Renaissance Italy to the discovery of women’s voices in 20th century America. The more that scholars write about previously forgotten figures like Madame Du Châtelet, the more other philosophers scour the archives and the historical record to find yet another hidden voice.

My own redemption came in the form of a digital humanities project here at Duke University, where I’ve taught philosophy for the past 15 years. In collaboration with an international team of scholars, a new website based at Duke, Project Vox, helps students and instructors reshape their teaching and research to include some of these forgotten voices. The website includes everything from sample syllabi to lengthy bibliographies to extensive discussions of the philosophical contributions of figures like Astell and Cavendish and Conway.

And 20 years after I was first shocked to find Kant’s lengthy discussion of a French woman I had never before encountered, it won’t surprise you to learn that our website includes a lengthy tribute to Madame Du Châtelet. I’m happy to say that it’s been read by thousands more people than my dissertation on Kant.

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