After America’s 2012 elections, many Democrats appear increasingly confident that their party has a new long-term advantage in American politics. Sooner or later, they will be proven wrong.

Division Is Human Nature

The idea that the Democrats are on the cusp of a permanent majority—which Democratic officials and operatives have articulated since November—rests fundamentally on the argument that structural changes and especially demographic changes in the American electorate will give the Democratic Party a much larger base than the Republican Party. Setting aside the fact that Republicans are already trying to develop a counter-strategy, this line of thinking ignores one of the central lessons of recorded human history as well as some very recent American political history.

Psychology and sociology have demonstrated compellingly that human beings and human societies have an irresistible temptation to divide themselves into groups. History and anthropology have documented this tendency from the tribal societies of the distant past to the city-states of ancient Greece and China’s warring states to twentieth century Europe. Political science has analyzed it around the world, from Yugoslavia to Rwanda and Sudan.

Of course, the same process that established modern nations occurs within them along ethnic, religious, class, and political lines, among others. Here, twenty-first century Europe is a perfect example; now that European states have settled their disputes, internal differences are intensifying and fueling independence movements in places like Scotland.

In American politics, George Washington was one of the first to warn vainly against the tendency toward division when he cautioned Americans to avoid “the spirit of party.” Unfortunately, his warning didn’t work—because it couldn’t.

Today, even if the Democrats’ wildest political dreams come true—and actually, especially if they do—these powerful urges will play out relentlessly inside the party. Just ask leading Republicans, who are engaged in a vicious and public internecine war that is primarily a consequence of their political successes, not their failures.

As Republicans increasingly captured state governments across America, they were tempted by the illusion of “permanent majority.” Karl Rove and others argued forcefully that American politics had evolved and that Republicans could seize upon new realities and new techniques to dominate the country’s political life.

Turning against Colleagues

The predictable problem with this was that once members of a political party believe that they have gained a long-term upper hand over their opponents, the battle with the other side becomes much less important and interesting than the fight to control their own side. Intra-party disputes inside the dominant party appear decisive in setting the nation’s course.

Republicans learned this painfully in Congressional primary races between establishment and insurgent candidates. And they saw it in a presidential primary that turned Republican candidates against one another to a degree unprecedented in recent decades. Rove is now leading an effort to promote moderate candidates, ironically combating the very forces he contributed to setting in motion.

The unraveling of a majority can move more rapidly or more slowly based on social, economic, and political conditions—and based on party leaders’ effectiveness in bridging the gaps within the dominant group. But once a majority believes it has won long-term power, the divisions are inevitable and inexorable. They are also usually fatal.

It is especially ironic that American politicians should fall victim to the mirage of permanent majority given their widespread view that one-party rule is unsustainable anywhere else in the world—which it is. Absent continuing brutal violence, something difficult to sustain indefinitely, one-party systems don’t survive their own internal divisions.

The divisions inside the Communist Party of the Soviet Union brought a leader in the party’s reformist faction to power and ultimately led to the USSR’s collapse. The same thing has happened in democracies like Japan, where divisions in the Liberal Democratic Party eventually split it apart and allowed an equally divided opposition party to take over—for a time.

And divisions in China’s Communist Party created the drama of the country’s recent leadership transition, making clear that however often Chinese leaders claim to have a one-party state, they actually don’t in the ways that matter. China’s citizens may not be able to choose their leaders, but they are well aware of the divisions inside their ruling party and know how to support one side or the other.

Any Democrats who think that their party is at the beginning of a period of long-term ascendency should take a hard look at political history in America and elsewhere. The Democratic Party is divided in the same way as the Republican Party over how strongly to adhere to and advocate its core principles and, if a critical mass of Democrats come to believe that their party is riding a rising demographic tide, these differences are likely only to sharpen and to bring about the same kind of split that the Republicans are facing. It might happen sooner or it might happen later. But it will happen.