The next chapter could be even worse. Even if some fraction of the opposition can reach an accord with the government, the area they could try to rule would amount to a rump state. The nation’s industrial heartland and most populous city, Aleppo, has been almost completely destroyed. Before the war, Syria’s manufacturing economy, education and health systems all functioned well by regional standards; they are unlikely to recover. The postwar landscape will probably play host to extremists, entrepreneurs of violence and widespread graft.

So why does anyone have hope for the talks in Geneva?

One reason is superpower politics. Russia and the United States are looking for ways to calm tensions, and diplomats from both countries believe an accord could lead to progress on issues they consider more important, like Ukraine. Another critical factor is exhaustion: Iran and Hezbollah backed the regime for years but, without Russia’s assistance, were unable to help it hold ground, much less win. Turkey, Saudi Arabia and the United States, the main sponsors of the opposition, have pulled back support whenever their proxies have surged, perhaps unsure that they’ll behave responsibly if they win power.

Syria’s civilians are desperate. The ranks of fighters are dwindling, especially on the government side. None of the parties have given up hope of outright victory, but an increasing number of rebels and midlevel government supporters acknowledge that they will either have to settle for a divided country or join forces with their sworn enemies. Some of the rebel commanders I interviewed in March said they believed the war had entered an endgame, but that it would take at least a few more years of fighting before serious negotiating would begin. Until now, none of the players have taken peace talks seriously.

Russia and America’s renewed engagement has drawn the notice of negotiators, but that means only that they believe they might be embarking on a real process — not that they expect a result soon. That rivals like Iran and Saudi Arabia, as well as Russia and the United States, will see eye to eye on a brokered deal to end the war is a long shot. But the idea that they would work together to prevent Syria’s continued decay into a zone of violence is an even longer one.

For now, Mr. Assad’s negotiators still consider the rebels “terrorists,” while the opposition insists that Mr. Assad, “the disease that struck Syria,” must step aside immediately. The state over whose fate they’re haggling, however, appears beyond salvaging.

