The same is true of the Republican Party in America today. Tea Party conservatives funded by the Koch brothers and other fossil-fuel donors are trying to wipe out whatever is left of the Republican Party’s polyculture and turn it into a monoculture. When Senate Republicans last week first offered their compromise proposal to end the shutdown, Representative Tim Huelskamp, a Tea Party congressman from Kansas, warned that, “Anybody who would vote for that in the House as a Republican would virtually guarantee a primary challenger” from the Tea Party. In short: They’d be purged in favor of a monoculture.

Image Thomas L. Friedman Credit... Josh Haner/The New York Times

When the G.O.P. was more of a polyculture, it gave us ideas as diverse as the Clean Air Act (Richard Nixon), daring nuclear arms control (Ronald Reagan), cap-and-trade to curb acid rain (George H.W. Bush) and a market-based health care plan (“Romneycare” in Massachusetts). The purge being mounted by the ultraconservative, oil-funded monoculturalists in the G.O.P. today will kill the Republican Party if continued. They will wipe out “all of its topsoil,” all of its rich nutrients, said the environmentalist Hal Harvey.

That is, unless the G.O.P. can avoid another lesson of Mideast politics: Extremists go all the way and moderates tend to just go away. With the feeble House speaker, John Boehner, and majority leader, Eric Cantor, consistently appeasing the Tea Party extremists, it is no wonder the party went over a cliff and almost took the country with it. But here’s another lesson I learned in the Middle East: It is not enough to just stop extremists from acting extreme. You have to take on and take down their ideas. After 9/11, Arab governments were more willing to arrest their violent fundamentalists, but few, if any, were willing to really take on and take down their ideas in public and offer moderate alternatives. Only Muslim moderates can take down Muslim extremists; only mainstream conservatives can take down Tea Party extremists.

It’s striking how much the Tea Party wing of the G.O.P. has adopted the tactics of the P.O.G. — “Party of God” — better known as Hezbollah. For years, Lebanese Shiites were represented by the mainstream Amal party. But in the 1980s, a more radical Shiite militia emerged from the war with Israel: Hezbollah. Under the leadership of Hassan Nasrallah, Hezbollah began to run for seats in the Lebanese Parliament in 1992 to change its brand. But it still refused to give up its weapons to the Lebanese Army, arguing that they were needed for “resistance” against Israel. Ultimately, Hezbollah could only win a minority of seats, but today it uses its arms and pro-Syrian allies in Parliament to block any policy it doesn’t like. As Hanin Ghaddar, the Lebanese Shiite writer who edits NowLebanon.com put it to me: “Hezbollah’s rule is: if we win, we rule, but if you win, you’ll think you rule, but we will do anything and everything to hinder you, and then we rule.”