The proportion of Americans who profess a religion is falling, but this decline is concentrated among liberal denominations. Traditional religion is gaining ground, among Jews as well as Christians. Does this trend constitute a repudiation of modernity? Eli Rubin’s new book, Kabbalah and the Rupture of Modernity, makes a contrarian claim: Jewish philosophical speculation, or Kabbalah, offers a path out of the paradoxes and contradictions of modern science. Published by Stanford University Press and exhaustively footnoted, Rubin’s book is the first full-length exposition of the thinking of Chabad, America’s most dynamic Orthodox Jewish movement. 

The Kabbalah to which Rubin refers has little to do with the New Age mélange served up under the name. Judaism is concerned first of all with the “what” of practice; the Kabbalah of medieval and Renaissance Jewish thinkers addresses the “why,” in the form of ontological speculation about the nature of Creation and God’s relationship to the world. It swayed seminal Western thinkers including Leibniz and Hegel. 

The Kabbalah of Isaac Luria (1534–72) has quasi-canonical status in the observant Jewish world, and points in remarkably modern directions. Rubin’s work helps explain why a deeply religious Jewish group thrives in the modern world.

Old-time religion, in fact, is thriving everywhere. Although Protestants no longer comprise an American majority, evangelical churches continue to grow at the expense of liberal mainline denominations. “Evangelicals now make up a clear majority (55%) of all US Protestants. In 2007, 51% of US Protestants identified with evangelical churches,” the Pew Survey reported in 2015. 

Tim Sullivan of the Associated Press wrote last year, “Across the US, the Catholic Church is undergoing an immense shift. Generations of Catholics who embraced the modernizing tide sparked in the 1960s by Vatican II are increasingly giving way to religious conservatives who believe the church has been twisted by change.” 

Liberal Jewish denominations (Reform, capital-C Conservative, and Reconstructionist) claim the affiliation of just 40 percent of American Jews. Among Jews older than 65 the proportion is 66 percent, a gauge of the generational shift from the older liberalism. A full 72 percent of American Jews intermarry, and their children lose the faith of their forefathers. In two generations, America will have a much smaller but much more observant Jewish population. According to a New York Jewish Federation study, Orthodox children make up nearly two-thirds (64 percent) of Jewish children in the New York areas, with the other 36 percent equally distributed across Conservative, Reform, and non-denominational/other denomination households.

But fully 37 percent of American Jews have engaged with the movement, whose adherents are instantly recognizable by their full beards and black fedoras. Chabad’s late spiritual leader Menachem Mendel Schneerson, the “Lubavitcher Rebbe,” guided the group from a small remnant of Holocaust survivors in 1951 to the world’s most prominent Jewish organization at his death in 1993. Chabad has grown exponentially since the passing of its leader. More than six thousand of the Rebbe’s shluchim, or emissaries, gathered in New York late last year—and they represented only a third of the corps of shluchim. Thirty years ago, there were just 300 at the annual gathering. There are now 1,060 Chabad Houses in the United States, more than the 960 synagogues of the Reform movement. Another 4,000 Chabad centers around the world provide religious services and kosher food for Jewish travelers.

Chabad are deeply observant—“Haredi,” or ultra-Orthodox—but do not demand observance from participants at their religious services and other events. It’s enough to come for the food; enjoy Judaism, and you’ll want more. But they expose unaffiliated Jews to the unadulterated religion of Jewish tradition. Their success parallels the rise of traditionalist Catholic and Protestant denominations; when Americans reach out for religion, they want the undiluted version. (Full disclosure: I am not affiliated with Chabad, although I often attend their services. The issues that separate Chabad Hasidism from my current Modern Orthodoxy, though, are of secondary importance to a general audience.)

Chabad has in common with other Hasidic movements an emphasis on joyful union with God, but with a difference: Its name is an acronym (Chochma = wisdom, Bina = discernment, da’at = understanding) reflecting the commitment of its founder, Rabbi Shneur Zalman of Liadi (1745–1812) to intellectual rigor. 

Eli Rubin’s book is the first full-length statement of Chabad’s philosophical program for an American audience. It makes the remarkable—and defensible—assertion that Jewish thought, and specifically the sixteenth-century Kabbalah of Isaac Luria, opens possibilities for modern science that are closed to the old determinism of pre-quantum science.

Secular Jewish outreach is less promising. In a recent book, Tikvah Fund chairman Elliott Abrams writes: “Most American Jews are not Orthodox and are not going to be. So, in numerical terms, the question is how nonreligious Jews, and those who say their religion is Judaism but do not actively practice the religion, can survive in a Christian America—or in a post-Christian America where religion plays a diminishing role in our common culture.” Abrams is not religious; we belonged to the same synagogue two decades ago, and I saw him twice a year, on the Jewish New Year and Day of Atonement. 

Abrams thinks that exposure to Israel through trips, summer camps, and study programs is the key to fostering Jewish “peoplehood.” But he notes with concern that the impact of time spent in Israel by young American Jews attenuates with time. “Some of the ‘first-decade’ data [for sponsored trips to Israel] ‘can be seen as disappointing,'” Abrams concedes. “Years later, 35% of participants say they feel ‘a little’ or ‘not at all’ connected to Israel, and among participants whose Birthright trip was ten to eighteen years ago, only a third (34%) had returned to Israel at least once—a lower number than might have been predicted.”

Israel is an inspiring country, to be sure, but there is a world of difference between Jewish tourism and Israeli identity. Almost all young Israeli Jews go to the army and stand ready to fight and, in case of need, die for their country, while their American peers are coddled and protected. Traditional Judaism, moreover, remains normative in Israel, unlike the United States. In Israel the synagogue you don’t go to is Orthodox. Only 13 percent of Israelis identify with liberal Jewish denominations.

Chabad’s claim that Judaism inspires discovery at the frontier of science may prompt the revival of a realm of Jewish thought that has been neglected in the past two generations.

Judaism is a love affair with God in which the ultimate sacrifice is ever in mind. Rabbi Joseph Soloveitchik explained that the daily ritual of placing tefillin—small leather boxes containing Biblical verses—on the head and arm reenacts Abraham’s preparation to sacrifice his son Isaac. The Jewish people survived without a state for 2,000 years because traditional Judaism evokes the same spirit of sacrifice that sustains today’s Israelis. 

This spirit infuses every aspect of Israeli life. In 2010, I reported on Israel’s preeminence in classical music, observing with Thomas Mann that the same qualities demanded by war avail the musician—the triumph of hope over fear.

Chabad’s bold assertion of religion’s preeminence over science has deep importance for religious outreach. Jews won a fifth of all Nobel Prizes in physics, but not one of the Nobelists was observant as an adult. To flourish, Judaism must persuade its most talented children that a passion for science and a passion for God are mutually reinforcing rather than antagonistic. Ultra-Orthodox Jews often view secular studies with suspicion. Chabad, in Rubin’s account, sees an inspiration for scientific discovery in Kabbalah. 

The claim that an ancient religion contains the seed-crystal of the modern outlook on science was advanced by the intellectual leader of Modern Orthodoxy, Joseph Soloveitchik (1903–93), in his essay The Halakhic Mind, and lectures published from student notes in the Jewish journal Hakirah (I explained Soloveitchik’s view here). At the heart of this claim is the assertion that the Infinite is immanent in the human realm. How is it possible to bridge the gap between human finitude and divine infinity? Isaac Luria argued that God Himself makes this possible by limiting Himself so that the divine presence can be accommodated in the finite world. God limited His transcendence and contracted His infinity to create an empty space for creation ex nihilo. This contrasts starkly with the passive, self-contemplating God of Aristotle or Plotinus, who presides placidly over eternal nature. 

Many of the great Jewish religious thinkers grappled with the implications of theology for science. Rubin writes:

[The Lubavitcher Rebbe] was one such thinker. He and R. Soloveitchik studied together at the Friedrich Wilhelm University of Berlin in the late 1920s and early 1930s. In terms of “scientific innovation” that “expands our scientific understanding of nature,” he wrote, nothing is comparable to the discovery of subatomic physics, “which brought about the disputation and rejection of many of the foundations of science—and which has many ramifications regarding free-choice, miracles and nature etc.” [The Rebbe] also regarded Kabbalah and science as related fields of study: “The association of the science of the chain of cosmic being in Kabbalah, and matters of practical kabbalah, to the natural sciences etc., is self-understood.” 

Rubin adds:

His theorization of the relationship between Torah and science was grounded in his understanding of the nature of Torah itself as an integral whole, at once singular and multifarious. But it was also grounded in his exposure to new advances in physics and philosophy as a student at the University of Berlin in the late 1920s and early 1930s. One of his professors was Erwin Schrödinger, who won the Nobel Prize in 1933 for his eponymous equation, which governs the wave function of a quantum-mechanical system.

He quotes the Lubavitcher Rebbe:

Most scientists have accepted this principle of uncertainty (enunciated by Werner Heisenberg in 1927) as being intrinsic to the whole universe. The 19th century dogmatic, mechanistic and deterministic attitude of science is gone. … Science must reconcile itself to the idea that whatever progress it makes, it will always deal with probabilities, not with certainties or absolutes. …

The clash between received religious dogma and ongoing discovery through the scientific study of nature has been one of the defining ruptures of the modern era. A straight line can be drawn from Cartesian dualism in the sixteenth century to Darwinian materialism in the nineteenth. In the twentieth century, however, the discovery of quantum physics ushered in an entirely new scientific era, marked by a new sense of mystery, uncertainty, and also infinite possibility. Some have seen this as a new opportunity for a rapprochement between religion and science.

The Greeks had no concept of creation, for an unchanging, eternal God would have to undergo change in order to make a world; thus both God and the world must be eternal. As Leo Strauss wrote, “According to the philosophers, not everything has come into being: that which truly is, has not come into being and does not perish.” How could an unchanging and eternal God create a world at a particular point in time? That implies that God changed and is bound by temporality. A related paradox is infinity: for Aristotle, infinity was inaccessible to human thought. For all their mathematical talent, the Greeks could not conceive of reckoning with infinite quantities, the foundation of modern physics. Isaac Luria cut through both paradoxes with a theological assertion: To create a world that was apart from God, God contracted within himself to create an emptiness in which a world might be created. That contraction, or tsimtsum, was the primal act of Creation. As Eli Rubin emphasizes, by confining His infinity to the human realm, God makes possible human creativity.

The great scholar of Kabbalah Gershom Scholem wrote:

The Divine as something turbulent is in the final analysis incompatible with the unmoved God. Such a thought could only arise when Greek thought overpowered monotheistic Biblical thinking. In the idea of tsimtsum, we have an infinitely bold expression for this profound turbulence in divinity itself. Only through this idea did the later Kabbalists believe it possible to attain a concept of the world in which things outside of the Divine essence could exist.

Divine self-contraction makes it possible to finitize the Infinite; that is the point of Calculus, which obtains finite solutions (integrals and differentials) from infinite series. A growing academic literature documents the influence of Jewish speculative philosophy (kabbala) on Renaissance and early modern thought, from Nicholas of Cusa through Leibniz. The influence, moreover, was mutual; Gershom Scholem argued persuasively that Isaac Luria’s Kabbalah anticipated Hegel’s Science of Logic, and Yale Professor Paul Franks has shown that prominent rabbis of the nineteenth century were deeply involved in the debates of German Idealism.

In the middle of the fifteenth century, the West began to see the world differently thanks to perspective in painting, and to hear the world differently thanks to tonal counterpoint in music. Alberti taught artists to order space by the vanishing point at infinity; musicians learned to “temper,” or adjust, the natural tones, opening up the universe of twelve musical keys. Physicists learned to calculate with infinite series and discovered the laws of planetary motion, the laws of mechanics, the trajectory of cannonballs, and the heat transfer of steam engines.

What Rabbi Joseph Soloveitchik called “Majestic Man” finitized the Infinite and gained mastery over nature and art. “Covenantal Man” tries to approach God but must retreat, because union with the Infinite dissolves the individual personality. In a 2024 essay for this publication, I cited the Bible’s great love story, Jacob and Rachel as an example of this duality.

Rubin’s detailed report of the evolving concept of divine contraction among Chabad’s sages over more than two centuries will challenge the general reader. It is more sourcebook than textbook, and has little to say about the interchange between Jewish and Western thinkers on these topics. The literature (especially in English) on this subject is at best nascent. A 2021 essay collection on tsimtsum and modern philosophy (reviewed here) failed to fill the gap. 

Rubin’s contribution to this literature is especially welcome because it comes from a vibrant Jewish movement rather than a recondite corner of academia. Chabad’s claim that Judaism inspires discovery at the frontier of science may prompt the revival of a realm of Jewish thought that has been neglected in the past two generations. The revival of traditional religion does not imply a repudiation of the beneficial accomplishments of modernity. On the contrary: It may prove an inspiration to scientists who have been wandering through a maze of ontological paradoxes since the advent of quantum theory.