The seventeenth century philosopher René Descartes is not the first thinker that comes to mind when it comes to ideas about how we ought to live. He’s most famous for his writings on metaphysics and epistemology, and not so much for his last book, The Passions of the Soul, which not only contains his theory of emotions, but also lays out in clear terms how we can live a life that is tranquil, peaceful, and even happy.

The book was written in response to a letter from Descartes’ long-time correspondent, Princess Elizabeth of Bohemia. Elizabeth wasn’t a prolific philosopher — her correspondence with Descartes contains most of her original ideas. But nonetheless, it was her objections that Descartes took most seriously (and if you ask me, never addressed fully — but that’s something for another time), and it was her request in a letter dated 13 September 1645 that prompted the Frenchman to write his final treatise.

Elisabeth of Bohemia, portrait via Project Vox

Descartes had long been concerned with how we ought to conduct our lives. In his 1637 book, the Discourse on the Method, he outlined a set of four maxims to live by, the famous morale par provision:

1. To obey the laws and customs of my country, holding constantly to the religion in which by God’s grace I have been instructed from my childhood, and governing myself in all other matters according to the most moderate and least extreme opinions — the opinions commonly accepted in practice by the most sensible of those with whom I should have to live.

2. To be as firm and decisive in my actions as I could, and to follow even the most doubtful opinions, once I had adopted them, with no less constancy than if they had been quite certain.

3. To try always to master myself rather than fortune, and change my desires rather than the order of the world.

4. To review the various occupations which men have in this life, in order to try to choose the best.

These four rules set the foundation of his moral philosophy, and while they don’t explicitly appear in any other text, they lay the foundation for what came later. As I’ll show, his mature thoughts about morality also depended on being firm in decision making, mastering oneself, and accepting sensible opinion.

Charles le Brun — the Expressions of the Passions

Ultimately, the Passions of the Soul is the text in which Descartes gave his final word about how we ought to live. This book is partly a text on the physiology and phenomenology of our passions, that is, those things that affect the mind as a result of its close connection with the body. He distinguishes six primitive passions from which all of the other affects can be derived: wonder, love, hatred, joy, sadness, and desire. Each kind of passion serves a different purpose and is associated with different kinds of bodily processes. In general, the purpose of the passions is to make us want the things that are good for us, and to motivate us to want to act on that. So, for example, when our body is starting to feel dehydrated, all else being equal, we’ll experience thirst, which will produce a desire to get a drink. If only it were that simple.

The problem is that the passions present the world to us in an exaggerated way. As Descartes puts it: “the passions almost always cause the goods they represent, as well as the evils, to appear much greater and more important than they are.” In other words, the passions make it pretty hard to act in the best way — after all, they can present something that’s like, alright, as being amazing, and something that’s mildly annoying as the end of the world. That’s a problem.

Descartes explains the problem as being that of having either a weak or a strong soul. The strong are those who can tame their passions relatively easily, while the weak are those who let the passions dictate what they do. The good news is that everyone, no matter how much their passions control them now, is capable of becoming strong in this regard. There are two things we can do about it — and one doesn’t quite work without the other. The first is to arm ourselves with our best judgments. The second is to cultivate within ourselves the passion of generosity. Let’s look at both of these a bit more closely.

René Descartes

When Descartes speaks of judgment, he has something very particular in mind. You might have heard of the Cartesian Method, what is that? In the Discourse on the Method, Descartes outlines a series of rules for how we can get to the truth. They are quite simple, and there are just four, so let me quote them in full:

The first was never to accept anything as true if I did not have evident knowledge of its truth: that is, carefully to avoid precipitate conclusions and preconceptions, and to include nothing more in my judgements than what presented itself to my mind so clearly and so distinctly that I had no occasion to doubt it. The second, to divide each of the difficulties I examined into as many parts as possible and as may be required in order to resolve them better. The third, to direct my thoughts in an orderly manner, by beginning with the simplest and most easily known objects in order to ascend little by little, step by step, to knowledge of the most complex, and by supposing some order even among objects that have no natural order of precedence. And the last, throughout to make enumerations so complete, and reviews so comprehensive, that I could be sure of leaving nothing out.

It’s only when following these rules we can get to any sort of certainty, or so Descartes thought. He elaborates on them more fully in his Meditations on First Philosophy, a text where he demonstrates how the method works, by first renouncing all of his beliefs, and then applying his method to finding out what it is exactly that we can know.

Even if that is what he has in mind, do we need to do the same thing? Perhaps — I think it is worthwhile to try to get the best evidence we have for our beliefs. As philosopher Patrick Stokes put it, “you are only entitled to what you can argue for.” The better your reasons for your beliefs, then the better those beliefs tend to be.

The second thing we need to do to tame our passions is developing and cultivating the passion of generosity within ourselves. This passion, Descartes thought, was the “remedy against all disorders of the passions” and it was the cornerstone of his ethical philosophy. Cartesian generosity consists of two things:

1. Knowing that nothing belongs to us but the freedom to dispose our volitions and that how we use this freedom is the only thing we can be praised or blamed for.

2. Feeling within ourselves a firm and constant resolution to use this freedom well; to never lack the will to undertake and carry out whatever we judge to be best.

Cultivating generosity, in other words, is cultivating within ourselves the idea that no matter what way our passions pull us, we can act differently, and that we ought to act on our our best judgements. You can see, then, why it is in fact judgment that we need to arm ourselves with to tame our passions.

Our affects present the world to us in an exaggerated way. Goods seem better than they are, evils worse. But, Descartes argues, if only we remember that we can only be judged by how we act in relation to how we see the world, and only try to act on our best judgments, then we can’t really ever be blamed for anything. All this is encompassed in the generous person.

Descartes thought that the generous person was naturally inclined to great deeds, but at the same time, they wouldn’t try to do things of which they are not capable. They would esteem nothing more than doing good to others. Most importantly, they would have complete command over their passions.

Unlike the Stoic philosophers, who are again quite fashionable, Descartes didn’t want his sages to rid themselves of the passions. After all, he thought, “persons whom the passions can move most deeply are capable of enjoying the sweetest pleasures of this life”. Sure, this also means that they could experience the most bitterness. But wisdom, Descartes says, lies in “teaching us to be masters of our passions and to control them with such skill that the evils which they cause are quite bearable, and even become a source of joy.”

Recommended reading:

Most of this article is drawn from Descartes’ Passions of the Soul. To my mind, the best English language edition is that in the first volume of The Philosophical Writings of Descartes edited and translated by John Cottingham, Robert Stoothoff, and Dugald Murdoch. That edition also contains the Discourse on Method, while the second volume contains the Meditations on First Philosophy along with selections from the objections and replies.

For the foundations and background to Descartes’ thinking on the passions, I suggest reading his correspondence with Princess Elisabeth, the best edition of which is translated and edited by Lisa Shapiro.