Can Stoicism teach us how to live? A lot of people seem to think so. They identify as “modern Stoics,” a movement that has gained traction over the past two decades, with thousands of members now congregating online and off to practice a self-help version of the philosophical life. They include athletes, military officers, CEOs, Silicon Valley entrepreneurs, and writers like The New Yorker’s Elif Batuman, who described in a 2016 feature for the magazine how the Stoic philosopher Epictetus helped her cope with a long-distance relationship and sneaky taxi drivers in Turkey.

Though modern Stoicism has its roots in the culture of self-improvement, it also has more serious philosophical champions. One of these is Massimo Pigliucci, whose recent How to Be a Stoic: Using Ancient Philosophy to Live a Modern Life proposes to bring Stoicism from “second-century Rome” to “twenty-first-century New York.” A professor of philosophy at the City College of New York, Pigliucci is best known for his work in the philosophy of science. In his latest book, he discusses his Catholic upbringing in Rome and his rejection of religion as a teenager. To find meaning in his life and, as he grew older, to prepare for death, Pigliucci tried out different systems of belief. Buddhism was “too mystical,” secular humanism “too dependent on science,” but Stoicism hit the spot. It was “a rational, science-friendly philosophy” that offered him an answer to the “most fundamental question: How ought we to live?”

In How to Be a Stoic, Pigliucci aims to demonstrate how we can use this philosophy to develop a moral character and attain peace of mind in three ways: by taking charge of our desires, by acting virtuously in the world, and by responding appropriately to events we can’t fully control. To update Stoicism for our 21st-century needs, he replaces its theology and cosmology with contemporary scientific views and applies it to the challenges we are likely to encounter in the modern world. Yet I question whether the core tenets of Stoicism can survive this reinvention—and even if they did, I remain doubtful that they provide the right moral and political framework for our time.

Like all philosophical schools in antiquity, the Stoics sought to determine what happiness is and how we can best achieve it. The Greek term for “happiness” is eudaimonia, which refers to something broader than just being in a happy state; it refers, roughly, to living a good, flourishing life. For most ancient philosophers, living virtuously was a key ingredient of eudaimonia. But the Stoics went further: Virtue, they claimed, is all we need. On this point they disagreed with Aristotle, who argued that people “talk nonsense” if they say that a virtuous person is happy even when he’s being tortured or experiencing great misfortune. The Stoics, however, stood their ground: A virtuous person, they held, is as happy on the rack as he is enjoying a fine dinner in his Roman villa surrounded by loved ones. So long as he (or she) is virtuous, the Stoic is happy under all circumstances.

The reason the Stoics made this claim is that, for them, everything that happens is part of a providential order, designed by a divine mind they identified with Zeus, the king of the Greek gods. Virtue, for the Stoics, consisted in living in agreement with that order. Once we understand that Zeus has arranged all things for the best, we can embrace life’s blows and its blessings as necessary to bring about the greatest good. In a virtuous life, moreover, the conventional blessings don’t matter—things like health, wealth, beauty, honor, or a wide circle of friends. These are things that we can’t be certain to attain, since they depend on chance or on other people’s opinions and actions. In Cicero’s words, they are all “eclipsed, overwhelmed, and destroyed by the splendour and grandeur of virtue”; that’s why misfortunes can’t upset the virtuous person. Of course, this doesn’t mean the Stoic won’t pursue such things like everyone else. But if Zeus’s plan requires that he fails to attain them, the Stoic remains unfazed.

Pigliucci’s challenge, then, is not merely to explain ancient Stoicism, but to make it convincing for the modern reader who doesn’t believe in Zeus and Providence. This is where he runs into trouble. To update Stoicism, he proposes replacing Zeus with what he calls “Einstein’s God,” which is simply the system of natural causes and effects, “understandable by reason,” that determines all things. But while the Stoics, like Einstein, equate “God” with the universe’s rational order, they mean something completely different by that: The universe is rational, they contend, because it is purposefully arranged by its maker. Einstein’s God, by contrast, isn’t a divine craftsman, but instead represents deterministic natural laws, as opposed to the randomness posited by quantum mechanics.

Einstein’s God will no doubt appeal more to Pigliucci’s readers than the divine craftsman of the Stoics. Pigliucci contends, moreover, that living well in the Stoic sense doesn’t depend “on whether there is a God” or what God’s “specific attributes” are. I strongly disagree. The practical part of Stoicism—the part where it teaches us how to live—doesn’t work without the outdated metaphysical underpinning. For the Stoics, Zeus made everything, including human beings, to maximize the universe’s perfection. What sets human beings apart is that they alone share in Zeus’s rational nature and can help carry out his plan by embracing the fate he has allotted to them. We are the only part of the universe that doesn’t just blindly function, but can grasp its task and perform it willingly. The key to happiness, therefore, is human reason, which enables us to understand Zeus’s plan and then direct our lives in accordance with it.

Pigliucci insists that from an evolutionary standpoint too, reason is a distinctive human trait. But even if we agree, it hardly follows that we should use our reason to live virtuously rather than, say, to outsmart our competitors in the pursuit of pleasure, power, or wealth. How Einstein’s God might offer us guidance here—how living in agreement with the deterministic system of causes and effects can make us virtuous and happy, or how it can reconcile us with our misfortunes as necessary for the universal good—Pigliucci doesn’t explain. In the end, I fear, Einstein’s God simply can’t do the job that Zeus did for the Stoics.

There’s another wrinkle: For the Stoics, living in agreement with Zeus’s providential order came with specific requirements such as caring for the well-being of others—not only our own near and dear, but all of humankind. Just as Zeus’s concern for human beings extended to everyone, ours should, too. Einstein’s God, by contrast, doesn’t care about anyone or anything. Thus, Pigliucci’s argument for embracing a similar humanitarian outlook appeals to an evolutionary understanding of social behavior: Care for others is produced by the “prosocial instincts” in human nature. But can we bank on those—and, assuming that we can, how far will they take us? As Adam Smith noted, perhaps with a hint of melancholy, we seem to help each other best when we act selfishly. He may be wrong, but is Stoicism really going to help us overthrow capitalism?

The Stoics also call on us to become cosmopolitans. Don’t say you’re an “Athenian” or a “Corinthian,” but “a citizen of the world,” Epictetus advises. It’s a fine quote for a cocktail party, but the reason the Stoics offer will not satisfy a devotee of Einstein’s god: They are cosmopolitans because there’s just one valid law throughout the universe, Zeus’s rational law.

The concrete examples of virtuous behavior that Pigliucci offers—such as eating at environmentally and socially conscious restaurants and investing via ethically responsible banks—are appealing enough. It’s just not clear what they have to do with Stoicism. Pigliucci’s values may be widely shared among his intended readers, but unlike Stoic virtue, which consists in living in agreement with Zeus’s plan, they have no firm philosophical foundation.

The general problem with Pigliucci’s approach should be clear by now. Many moderns may find a philosophy attractive that admonishes us to be rational, social, and cosmopolitan. But on closer inspection, the original Stoic arguments for these values have lost their bite, dependent as they are on a providential world order. Meanwhile, the updated Stoic arguments that Pigliucci proposes don’t have enough bite to begin with.

For Pigliucci, Stoicism’s main benefit is that it teaches us how to face adversity with equanimity. The examples he offers include food poisoning, an obnoxious cell-phone user at the movies, a stolen wallet, a genetic disposition to obesity, and not getting a job promotion. These things won’t upset us, he suggests, if we keep in mind the Stoic “dichotomy of control.”

According to the Stoics, our happiness depends only on what is up to us, not on external circumstances that we can’t fully control. We can strive to get a good job, stay healthy, raise a thriving family, or find interesting friends, but whether we succeed is only partly in our power. If you were born in a Mumbai slum, for example, the deck is stacked against you from the very start. By contrast, how we judge things is up to us, and judging them correctly is all we need to be happy. And judging things correctly, in turn, means affirming everything that Zeus’s providential order has in store for us, because we recognize that whatever it is, is necessary in order to bring about the best possible world under his divine plan.

Pigliucci turns this idea into something very different. We can endure misfortune with equanimity, he argues, if we realize that the outcome isn’t under our control and that the universe doesn’t care about our purposes. He also recommends various exercises to cope with misfortune: for example, what he calls praemeditatio malorum—meditating on the worst things that can happen to us, so we’re prepared if they do and thankful if they don’t. He also offers solid commonsense advice: Instead of letting anger consume you when misfortune strikes, Pigliucci counsels, remain cool and troubleshoot—for example, quickly cancel your credit cards if your wallet gets stolen. But the connection to Stoicism is again unclear. For the ancient Stoics, the universe does care: It is arranged in the best possible way, especially for humankind, its most valuable part. For the Stoic sage, there are no mala—bad things—to meditate upon, since all things are part of Zeus’s flawless plan.

To see that Pigliucci’s proposal doesn’t work, just scale up the degree of adversity: Instead of stomach pains and pickpockets, think of a Holocaust survivor who learns that the rest of his family has perished in the death camps, or a Syrian refugee who watches his son’s dead body wash up on the shore. The Stoics thought their tools worked even in these extreme cases: Epictetus tells us in the same breath not to get upset about shattered china or the death of loved ones. But recognizing one’s lack of control and the universe’s indifference, as Pigliucci proposes, won’t yield equanimity in the face of such loss. And that’s a good thing.

The larger question here is whether the politics and ethics that modern Stoicism proposes are the right ones for our age. Many Stoics, Pigliucci claims, were “bent on changing the world for the better.” But they weren’t: They would have dismissed as incoherent the idea that one can improve what is already in the best possible state. They could, however, justify activism as an effort to help implement the divine plan. But what happens when few agree on what this plan might be—or even whether there is one? In a universe that doesn’t care about our purposes—a universe ruled by Einstein’s God, not the divine craftsman of the Stoics—creating the conditions for human flourishing becomes our job. We cannot just come to terms with the way the world was ordered by some higher power; we have to order the world ourselves. Pigliucci says, for example, that “it is not in our power to make thievery disappear.” But we’re much more likely to get mugged in Rio de Janeiro than in Stockholm—and that’s the outcome not of Providence but of human-made social orders. Realizing that the Stoics’ tools to cope with adversity no longer work is a powerful incentive to minimize the need for them, whether by advancing medicine and technology or by championing social justice and human rights. On the whole, the Stoics were much more focused on coping with the world as it exists and as we suffer in it than on changing it. That’s not surprising, given their core beliefs: that we live in the best possible world and that happiness is available under all circumstances. But if you don’t share these beliefs, then developing vaccines and fighting economic inequality is time better spent than searching for philosophical consolation.