Something strange has occurred in American politics. The 2016 presidential race—marked by a feverish populism, in a country with one of the most religious populaces in the industrialized world—is experiencing a secular insurgency. Donald Trump has drawn support from evangelicals despite (not because of) his personal piety. No one missed Trump’s mangling of scripture at his Liberty University talk, nor the comparison of his Art of the Deal to the Bible itself. Meanwhile, Senator Bernie Sanders would be the first agnostic president, albeit of Jewish descent. Sanders even went so far as to distance himself from his youth on a kibbutz in Israel, and his campaign is being run along starkly secular lines. (Compare this to Joseph Lieberman’s far more pious run in 2000 with Al Gore.)

This secular turn is notable because this election marks the transfer of power from the presidency of Barack Obama, who riled many on the religious right for his apparent lack of piety, explicit opposition to the Defense of Marriage Act, and has even been accused by some on the political fringes of being a “secret Muslim,” “atheist,” or—astonishingly—both. But the difference between Obama and Sanders is that Sanders doesn’t make a pretense of being religious, while Obama got his political start organizing in Chicago-area churches. And Trump is hardly the paradigm of sober virtue: He’s been divorced twice, and has a track record of being liberal on a number of key social issues, including abortion. He was even recently attacked (unsuccessfully) in a Ted Cruz robocall for his former support of gay marriage.

This race reveals, more broadly, three different modes of secularism in American politics. With Sanders, personal faith appears not to determine public policy whatsoever. At most, Sanders appeals to a broad, intuitive humanism, and has described himself as “spiritual,” but outside of any organized religion. Hillary Clinton, following the model of Obama, has professed deep personal roots within organized religion. As a practicing Methodist, Clinton explicitly claims that her personal faith inspires her policy stances, proclaiming in Iowa, “I would say I am a Democrat because of my Christian values.” Yet, when it comes to Clinton’s specific policies, they are defended in terms of practical costs and benefits, and not through invocations of God’s will. Trump, meanwhile, espouses a secular politics, yet geared towards the protection of Christian—especially evangelical—ways of life against the so-called PC culture.

As diverse as these modes of secularism are, what they all have in common is the basic separation between a private sphere of religious belief and the public sphere of policy. Private belief can inspire policy, and policy can defend religious interests; but only from afar, and each from within their own proper domains. This is best expressed philosophically in John Rawls’s formulation of liberalism. The essential claim here is that the adherence to “comprehensive doctrines,” or in other words, absolute truth claims about reality, are an anathema to free public discourse in a democracy. Such strong beliefs may be held privately, but they cannot be allowed to bleed into public discourse. Even a certain strain of conservatism (especially American Neoconservatism) has assented to this “amicable separation,” as Leo Strauss perennially warned against the rise of a “Philosopher-King”—lest he become an absolute tyrant.

We may contrast these secular positions with Ted Cruz’s conservative Christian critique. For Cruz, politics is grounded in morality, and morality is grounded in a Judeo-Christian ethic. Thus, public policy is first and foremost a religious mission, invoking along with Ronald Reagan the construction of a “shining city on a hill.” Rights are not granted by governments, but instead, “Our rights come from our creator.” As such, we can contrast the candidacies of Cruz and Trump when it came to the Kim Davis affair. When Davis went to jail for refusing marriage licenses to same-sex couples in Kentucky, Cruz was one of the first politicians on a plane to lend his personal support. Trump by contrast invoked the “rule of law” against Davis’s attempt at civil disobedience. This, however, did not stop Trump from advocating such other policies as banning all Muslims from entering the U.S. The common thread? Trump is willing to use state power (even beyond the limits of the Constitution) to encourage a more “traditional” American constituency, but will not subordinate state power to narrowly religious interests. That is the difference between Trump and the Moral Majority.

As much as both Trump and Sanders are insurgent candidates remarkable for their populism and secularism, there is a noticeable difference in vitality between the national spectacle surrounding Trump and the mostly young and generally higher educated supporters of Sanders. One may speculate that Trump’s disavowal of a consistent, religious worldview has been replaced by an equally energizing, alternate worldview, sometimes characterized as the “new white nationalism.” Endorsements from the likes of Don Black (Stormfront), and both David Duke and Tom Metzger (former KKK), may lend credence to this claim—or maybe there is just something sui generis to Trump’s personality.

Whatever the case, on the Sanders side of the equation, the absence of a religious worldview finds no clear replacement. Sanders does not have the sort of pop-culture celebrity Trump has accrued since the mid-1980s. More importantly, Sanders lacks a concrete secular outlook beyond his often vaguely stated humanism. This absence of a determinate worldview, one can argue, has contributed to the difference in energy between the two campaigns.

Perhaps Rawls and the contemporary liberal tradition have gotten something wrong. Perhaps one does need a coherent worldview to undergird a consistent, emancipatory politics. This runs counter to the sorts of pragmatism and post-structuralism that have marked left-wing discourse since the fall of the Berlin Wall. What we are now noticing, under the surface and at the margins, is a pendulum swing in the other direction: a rediscovery of core Enlightenment principles, i.e. the original basis for modern political emancipation. This phenomenon has been happening in academia for a decade or so, and has filtered into popular political discourse as of late. This is evidenced, for example, in the historian Jonathan Israel’s Radical Enlightenment scholarship and his forays into cultural commentary.

From the pages of the New York Times, The Nation, and the New Republic, the thesis of Radical Enlightenment has been debated and contested. On the one hand, Israel has encountered criticism from Samuel Moyn, a skeptic about the Enlightenment’s legacy. As Moyn put it in The Nation, “[S]everal centuries on, the Enlightenment has not yet succeeded in either breaking the shackles of outworn creeds or lifting the yoke of scandalous oppression across the globe.” On the other hand, Lynn Hunt decries the Radical Enlightenment thesis for its supposedly simplistic dualism and lack of political sophistication. In her review from 2014, Hunt argues that Israel “thinks about philosophy and philosophers in obsessively dichotomous terms. On the one side are … the true radicals because they are materialists, atheists, and allegedly therefore democrats … On the other side are the insufficiently radical philosophers whose influence can lead to no good …”

However, Nick Nesbitt articulates a third position, which accepts Israel’s Radical Enlightenment thesis but expands its effect to include political movements such as the Jacobinism of the French and Haitian revolutions. It is this acceptance and modification of Radical Enlightenment—one might say, the radicalizing of the Radical Enlightenment—that we are calling for here: the reintroduction of Enlightenment principles to ground Left politics today.

But what comprises this Enlightenment worldview, a tradition bridging thinkers as diverse as Spinoza and Marx? Provisionally we may identify five essential, and interlocking, elements:

Rationalism would be the first principle of such an outlook. Despite the age-old charge of intellectual hubris, the Radical Enlightenment belief is that the universe is essentially knowable and that all limits to knowledge are merely provisional.

Materialism, as a second principle, proceeds naturally from the first. Human beings are not a special “state within a state,” but are thoroughly part of nature. Intelligible laws of cause and effect determine human beings and social behavior no less than other natural phenomena. This colors how we think of social and political problems, as not stemming from unnatural and wicked desires, but instead from perfectly comprehensible causes.

Humanism, as the third principle, draws out the implications of our material existence. Since all people are conditioned by common, natural laws, then there can be no stark separation between different peoples, sexes, races, etc. Diverse needs, desires, and conditions of flourishing are ultimately translatable across all parochial boundaries. (For instance, the Black Lives Matter movement is predicated upon the value of human life as such, and simply highlights the ways in which our society systematically brutalizes and ignores one section of humanity.) More broadly, humanism grounds an internationalist disposition in politics.

Hedonism marks the basic disposition of human beings towards their environment and one another. Here a contrast is useful: Against the otherworldliness of the Middle Ages, which saw humanity’s bodily nature as “corrupt,” hedonism asserts that we need not fear the “garden of earthly delights.” This ethical naturalism is a departure from the exaggerated humility, chastity, and pious shame of an earlier worldview which still haunts us today.

Perfectionism, finally, combines all four of the above principles into a philosophy of history and action. Humanity, through common reason and a desire for happiness, is naturally capable of solidarity for the achievement of overarching projects—i.e. the increasing “perfection” of our worldly lot. This deterministic worldview, therefore, is far from a resigned fatalism. For in comprehending the order and connections of things, we can move forward to actively conquer fortune” together.

To be sure, the above considerations may strike the reader as overly speculative and abstract, not least since we find ourselves in the midst of a frenetic campaign season. We do not pretend to be offering timely campaign advice; what we do submit, however, is that the broader revitalization of left-wing politics (beyond this campaign season) requires a deepening of left-wing consciousness. The rediscovery of the Enlightenment project will be necessary, but by no means sufficient, for this revitalization. This will entail applying the above principles to a clear-headed, empirical analysis of the material conditions all around us.

As a candidate, Sanders is quickest to point out the decades-long stagnation of real wages. To address this decline, Sanders supports a $15 minimum wage by 2020. In terms of finance, he has supported the reimplementation of the Glass-Steagall Act and the breakup of the nation’s biggest banks. All of this would mean policies directed towards the redistribution of wealth and the curbing of corporate malfeasance responsible for the 2008 financial collapse.

However, the philosophical values delineated above call for a much broader vision for restructuring the economy. The overriding principle of rationalism implies that people ought to have conscious control over the greater part of their lives, the perfection of their talents, the ways they contribute to society, and how they cooperate with others. In the twenty-first century, as a matter of fact, the majority of most people’s waking hours are spent at their job. Thus, a Radical Enlightenment ethic as applied to today means the democratization of daily economic life: not just redistribution, not just state ownership of large industry or banks, but the conscious, democratic control over people’s own workplace. This includes not only long-term production plans, but also discretion over daily necessities: everything from staples and spreadsheets, to hiring and firing.

Sanders falls short of this vision. A plaque honoring Eugene V. Debs sits in Sanders’s office, but while Debs championed democracy in the workplace, Sanders runs a New Deal–style, populist campaign. Consistent with this contrast, Sanders lacks a transitional program to bridge the necessary demands of today with an emancipatory project for the future.  

Sanders can of course be forgiven for not explicitly speaking about philosophical principles on the stump. He is a politician, not a metaphysician. To speculate as to whether he does indeed share in this Enlightenment worldview is likewise a dubious task. One mustn’t make windows into the souls of men.

However, if Sanders had consistently applied these principles to the circumstances of our day, he may very well have taken different positions on a host of other issues as well. He may, for example, have opposed the F-35 warplane program in his home state of Vermont, and not enthusiastically advocated that repressive regimes like Saudi Arabia and Egypt intervene in Syria. These are, in any case, some of the most common criticisms of Sanders by his own supporters on the left, such as Mike Davis and Kshama Sawant. Such criticisms may be directed even more emphatically against Clinton’s hawkish foreign policy record.

More to the point, it is only a movement steeped in Radical Enlightenment principles that will develop ever more coherent political demands, and for the very same reason will achieve new levels of vitality and purpose for the road ahead. While Sanders promotes a political revolution, one cannot have a revolutionary movement without a revolutionary theory.