S omething there is that doesn’t love a wall, That wants it down," wrote Robert Frost. Martha Nussbaum doesn’t cite Frost directly, but the spirit of that poem hovers over her new book, even if what she has in mind is less Frost’s rural New England than Thomas Jefferson and the conventional shibboleths of East Coast liberalism. In this powerfully argued and often moving book, Nussbaum, a distinguished professor of philosophy at the University of Chicago, takes a deftly wielded sledgehammer to the "wall of separation" between church and the state much beloved of liberals–not, as some would have it, to allow a religious takeover of the public sphere, but to make for a neutral public sphere, safe for religious and non-religious citizens, of all shapes and sizes. Informed by religious teachings and traditions, she argues, this approach would in turn make for a richer liberalism.

I live in Jerusalem, where we are surrounded, and often defined, by walls of all kinds. Stepping out of our apartment building in the Abu Tor neighborhood, at one end of the block you can see the walls of the Old City, and at the other the separation wall between Israel and the Palestinian territories and, off in the distance, the Judean desert. The Old City walls project a stately image of an ordered world; the separation wall, a much darker image of a bitter conflict in which religious and national identities are hopelessly intertwined. Living here has taught me that the world needs America, because the world needs hope, including the hope that religious-national conflict is not the last word in human experience. This makes Nussbaum’s book an important read, but a poignant one too. Can all people–wherever they are and whatever they have inherited–live by the conviction that all men are created equal? She thinks so. I hope so.

As her title makes clear, in Nussbaum’s reading, the American constitutional tradition, thought through to its deepest intentions and most enduring foundations, is concerned above all with equality–with enabling all citizens to cultivate themselves and act on their moral choices in keeping with the dictates of their consciences, by the lights of their various religious or non-religious traditions, and in peaceful concert with others. She repeatedly argues, in a manner at once philosophical analysis and a lawyer’s brief (she does, after all, have a joint appointment at Chicago’s law school), that the idea of "separation" is, true to its name, a barrier to genuine understanding of the Religion Clauses in the Constitution, an understanding better captured by equality and the religious neutrality that term implies.

Nussbaum wages a dual polemic. On the one side, she departs from conservatives like Antonin Scalia who are willing to countenance varying forms of government engagement with specific, and usually majority, religion in the public square. On the other, she takes on liberals who dismiss religion as a tissue of nonsense, a stance which she believes unnecessarily denigrates vast masses of the citizenry and shortsightedly dispenses with the positive resources religion offers for individual moral cultivation–and thus for democratic citizenship.

Nussbaum walks through the history of the First Amendment’s Religion Clauses, addressing specific themes in the context of the times in which they arose as matters of discussion and controversy. The hero of her narrative is Roger Williams, best known as the founder of Rhode Island and, since his scholarly rediscovery in the 1950s, hailed for the proposition that disestablishment benefits religion and keeps it out of the clutches of the state. But, following other more recent scholars such as Clark Gilpin and Edwin Gaustad, and drawing on her own intensive reading of the primary sources, Nussbaum goes further still, arguing that Williams’ defense of religious liberty–liberty of church from state and individual from church–was not merely a prophylactic against majoritarian persecution. Rather, it was grounded in a deep conviction about the "holy Light" of conscience: a universal, God-given faculty of freedom of thought and decision shared by all people, no matter their specific religion. God wants His creatures to choose well, which also entails choosing for themselves in freedom.

Nussbaum has written elsewhere, among other things, substantial and important works on Stoicism and its resonances for contemporary moral life, and she sees a strong Stoic influence in Williams and other early American thinkers, Christians and Deists alike. While she is undoubtedly right on that score, at the same time Williams was deeply Protestant–often in ways deeper than she acknowledges–ways that have significant implications for the ability of his ideas to travel.

Alongside her hero Williams, in a supporting–and, at times, troublesome–role is the better-known and vastly more influential John Locke. "Locke diverges from Williams," she finds, "by explicitly insisting that once a generally applicable law has been made by an impartial principle in a sphere the state regulates, people may have no dispensation from that law for religious reasons. If their conscience leads them to disobey, they will just have to pay the price and go to jail." Williams, by contrast, maintains the inviolability of conscience–and its God-given right to express itself in action. These two positions came together at the founding of the Republic, and the tension between them plays itself out in constitutional jurisprudence down to the present.

Indeed, when it came to fashioning a public sphere at the Republic’s founding, James Madison, in his 1785 document "Memorial and Remonstrance Against Religious Assessments," channeled Williams in his reading of the "self-evident" truth of equality as expressed in the Declaration of Independence: "If ‘all men are by nature equally free and independent’…Above all are they to be considered as retaining an ‘equal title to the free exercise of Religion according to the dictates of conscience.’" Thus the two Religion Clauses of the Bill of Rights together establish the equality of citizens. The Establishment Clause prevents government from unequally distributing burdens and benefits on a religious basis, while the Free Exercise Clause secures the protection of individual conscience and its expression in action.

In Nussbaum’s telling, it was not until the twentieth century that the constitutional tradition of political and civil liberties came to a deeper self-understanding: that protection of individual conscience is at the very heart of the Religion Clauses’ protection of minorities. And, we might add, of the public sphere. Her account of the postwar era, a crucial period here as elsewhere in Constitutional law, begins with the 1947 decision Everson v. Board of Education, in which Justice Hugo Black decided that a tax subsidizing student transportation to Catholic schools, along with other non-profit schools, did not violate the Establishment Clause. The decision, in Nussbaum’s view rightly decided, nonetheless made a crucial and problematic move, invoking Jeffersonian "separation" while deciding the case on essentially neutrality/fairness-cum-freedom of choice grounds. Right result, wrong reason. Why? "The rhetoric of ‘separation,’" Nussbaum writes, "applied without a deeper theoretical analysis, wrongly suggests that the goal of the Establishment Clause is to purify the public square of all reference to religion, in effect establishing secularism as the theory of government."

This notion of "separation" came to full and problematic doctrinal flower in the much-cited 1971 case Lemon v. Kurtzman, in which the Supreme Court enunciated a famous "three-pronged" test , by which government action concerning religion "must have a secular legislative purpose"; its principal effect must be one that "neither advances nor inhibits religion," and it "must not foster an excessive entanglement" with religion, a formulation which was taken by many to inscribe "separation" into the very mechanics of constitutional adjudication.

Nussbaum writes that this sense of "separation," which has come to define most liberals’ position on religion in the public sphere, muddies the equality principle and creates unnecessarily contorted questions of government involvement in the activities of religious people and organizations, in an era in which government is ubiquitous in citizens’ lives. Moreover, liberals’ reliance on the language of separation enables them to overlook the rich and complex religious traditions themselves; as a result they fail to see that genuinely religious people may themselves be offended by Creationism and by a Pledge of Allegiance that includes the words "under God."

A better version of separation, she writes, is the "endorsement test" put forth by Justice Sandra Day O’Connor in 1984’s Lynch v. Donnelly. It holds that the test for a government action is whether it sends "a message to non-adherents that they are outsiders, not full members of the political community, and an accompanying message to adherents that they are insiders, favored members of the political community." This test, Nussbaum writes, makes better sense of "separation" by highlighting that a constitutionally illegitimate engagement with religion is one which "offends against other constitutional values, above all liberty and equality." O’Connor’s test thus makes it possible for government to engage when necessary and desirable with religion while maintaining the core idea of equality.

"Endorsement" is nonetheless a subtle idea, and it has–in more conservative jurisprudence as enunciated by, among others, Scalia–shaded off into the idea of "noncoercion," which holds that government engagement with religion is bad when coercive (e.g., tax money used for religious schools) and fine when ostensibly non-coercive (e.g., religious displays on public property). Nussbaum points out, however, that such a reading simply collapses the Establishment Clause into the Free Exercise Clause, and it does nothing to prevent preferential treatment for one (almost invariably the majority’s) religion.