Politics, the saying goes, is the art of the possible; yet this hard-earned bit of wisdom is too frequently forgotten by the very people most determined to bring about political change. Take, for example, the last-ditch effort to cripple health-care reform—by the left. Initially, progressives rightly insisted that any reform bill include a public option. When, after months of hard fighting, it became clear that the votes for a public option just weren’t there, some advocates accepted the setback and moved on. But others, pronouncing the whole process irredeemably corrupt, turned against the Affordable Care Act. Thus former Vermont Governor Howard Dean, fresh off a turn as chair of the Democratic National Committee, declared in the final weeks of debate that any bill without a public option “is worthless and should be defeated.” Just days before the Senate vote, he reiterated that “if I were a senator, I would not vote for the current health-care bill.” The message was clear: Purity in defeat is better than victory through compromise. 

Luckily, the “worthless” health-care bill survived its progressive critics and is now benefiting millions of Americans. Yet the ideological impulse that threatened to derail it lives on. It reemerged in the pious antipolitics that doomed Occupy Wall Street, as well as in a spate of foreign-policy broadsides from left-wing pundits (motivated by events in Syria) that effectively called for an end to liberalism’s tradition of humanitarian intervention. With Democrats in control of the Senate and White House, the left’s pragmatists are in the position to bail out its purists. But that could all change the next time the Democrats lose a big election. And if the left’s purists do regain the upper hand, it could be a while before the Democratic Party recovers.

If you doubt the cost of indulging in political pieties rather than political organizing, compare the influence of Occupy Wall Street with its conservative counterpart. While Occupy largely fizzled out in less than two years, conservative activists are still jostling for control of the GOP nearly five years after Rick Santelli’s infamous rant on CNBC calling for a “Tea Party.” To be sure, the two groups are not exact parallels—and well-funded Tea Partiers found easier allies in the GOP than OWS did among Democrats. Even so, it’s impressive to recall that in less than a year, Tea Party activists managed to snatch Ted Kennedy’s Senate seat away from the Democrats. Occupy can claim no similar coup.

Indeed, most OWS activists actually disparaged political involvement as a game for patsies and stooges, a way of playing into the hands of the same corrupt system they were trying to change. Surprisingly, many liberals agreed. As one writer at the center-left Washington Monthly commented approvingly, “Protesters aren’t demanding Congress pass a bill or approve a specific reform. They’re shining a light on systemic problems that can’t be fixed with one bill or one reform.” And yet, however admirable, “shining a light” by itself changes nothing. Sadly, Occupy proved equipped for little else; like health-care activists stung by the defeat of the public option, most Occupiers concluded that political engagement would taint their cause. Trapped in this circular and self-defeating reasoning, the most promising left-wing protest movement in decades faded quietly into the background.

Antipolitical idealism also threatens to handcuff the Democrats in their efforts to formulate foreign policy. When the United States seemed ready to bomb Bashar al-Assad’s forces in Syria last fall, liberals were almost unanimous in their skepticism—or outright opposition. Unexpectedly, however, the president’s interventionist threats—vigorously denounced by many on the left—led to Syria’s capitulation on chemical weapons. In that sense, the deal was a success. But it was also a useful reminder that the exercise of power rarely escapes some complicity with evil: the deal came at the great moral cost of accepting the continuation of Syria’s horrific civil war. Opponents of intervention in Syria have frequently failed to acknowledge these complications, or to admit that Obama’s threat reduced the risk that chemical weapons will again be used against Syrian civilians.

A foreign policy that abandons America’s moral commitments by renouncing humanitarian intervention will undermine the long-term interests of the United States while putting millions of innocent lives in danger. Yet on the left, the political momentum is with those who are opposed to a broad range of interventions (and not just military ones) intended to prevent mass killings. In these pages, for instance, David Rieff charged Samantha Power, the U.S. ambassador to the UN, with “enthusiasm” for intervening in Syria, and accused the Atrocities Prevention Board that she helped found at the White House of bearing a “hubristic” name (“Reckless Ardor,” June 14, 2013). Such criticism unhelpfully blurs the distinction between interventionists like Power, whose goals are humanitarian, and people like Weekly Standard editor William Kristol—borderline neoimperialists who long for American dominance. After all, one major purpose of the Atrocities Prevention Board is to stop crises before they descend into outright slaughter—leading to fewer occasions for possible military intervention. (Indeed, the APB has recently been praised for its unprecedentedly rapid response to violence in the Central African Republic, which may yet stop a genocide before it starts.) By treating Power’s initiative with hostile suspicion, anti-interventionists are helping to undermine any real distinction between humanitarianism and imperialism.

An eagerness to dismiss that distinction was evident in much of the opposition to strikes against Assad. The New York Review of Books published a piece by David Bromwich titled “Stay Out of Syria!” There Bromwich accused writers who wrung their hands over U.S. inaction in Syria, like the New Yorker reporter Dexter Filkins, of “looking for reasons to intervene.” Meanwhile, “in honor of the coming Syria intervention,” the editors of the journal n+1 re-posted a piece originally written about Libya that objected to the frequent use of words like “slaughter” and “massacre” in Samantha Power’s 2002 book on genocide, A Problem from Hell. “The function of these words,” they wrote, “as well as the word ‘genocide’…is to place the evil people beyond the pale of politics, of negotiation, of human intercourse…. Thought, strategy, negotiation shut down; there is only right and wrong, only fight or flight.” Toeing the anti-interventionist line, they implied that to wonder whether the people of Homs deserved our help—and not merely our pity—was to become a reckless proponent of American empire. The editors closed with a question that loomed over the entire left-wing debate on Syria: “Has there ever been a truly successful, truly humanitarian humanitarian intervention?” (their italics).

THAT LOADED PHRASE, “truly humanitarian,” captures the spirit of a moral purity that would—in a macabre irony—effectively condemn millions of defenseless people around the world to exile, torture, rape, and death. Even to pose such a question is to fail to understand that there is no such thing as clean hands in politics, let alone in international affairs. The editors of n+1 complain that genocides in Cambodia and Bangladesh were halted by armies with their own less-than-pure reasons for intervening, and that Kosovo remains unstable more than a decade after its rescue by NATO. But there is no contradiction in mourning these outcomes while still insisting that they are preferable to mass slaughter. Even the strongest skeptics of intervention should be able to acknowledge that fact.

This is not to argue that U.S. intervention in Syria would have been wise or effective—in fact, the anti-interventionists  were right in this case. There are many instances where intervention is simply not possible. But does that mean liberals should rule out ever intervening, no matter how grave the crisis? As n+1’s critics pointed out, the magazine was in effect advocating outright pacifism. The moral zeal of that position tends to blur distinctions between armchair imperialists and those who feel morally compelled to acknowledge the possibility that U.S. military action might sometimes be necessary.

In 1947, while lecturing on Shakespeare at the New School in New York City, W. H. Auden reflected on The Tempest and its protagonist, Prospero. Much preferring the solitude of his library to his political duties, Prospero entrusts his day-to-day tasks to his brother and retreats into his studies—only to be overthrown by his treacherous sibling and sent into exile. To Auden, the message was clear: “Prospero wished to improve himself, and that takes time, but government has to go on now.” He repeated the point for emphasis: “It is desirable for the best people to govern, but we can’t wait—government must go on now.”

Prospero’s temptation is all too familiar to American liberals, who since 2008 have been engaged in a very public struggle with the burdens of power. When liberals have failed in recent years, it has often been because they have demanded moral purity when they ought to have accepted political efficacy. Certainly, there is wisdom in understanding that power is difficult to reconcile with justice. But as Prospero learned, it is worse still to wait around for perfection, if only because history itself does not wait. Some compromises, of course, are impossible to accept. But we can’t wait for all our moral dilemmas to be resolved before acting. Government has to go on now.