Firstly, how are you going to draw lines that please everybody or avoid ethnic cleansing? There are huge Sunni minorities in the South, and large Shi'ite minorities in the middle. Baghdad is very mixed. Even the Kurdish populations are mixed with Arab populations in Baghdad, Kirkuk, and Mosul.
Secondly, this isn't some inevitable result. YES, Iraq was ethnically diverse. YES, there were historical rivalries. But that's true of lots of countries, and it doesn't inevitably mean a country has to break up. Shi'ite Iraqis were just as patriotic and nationalistic during the Iran/Iraq War as Sunnis. Also, if you read Iraqi blogs or watch documentaries about Iraq (or look at polls), one common feature is that relations between Sunnis and Shias on an individual level have long been fine. There are very high rates of intermarriage, etc. The main problems have had to do with patronage, historically.
The current ethnic fighting wasn't inevitable; otherwise Iraq would have broken up long ago (it wasn't always as autocratic as under Saddam; it was even relatively democratic in the 1950s). The current situation is the result of a power vacuum; in such a climate, public order breaks down and extremist groups can operate freely; this leads to political polarization and sectarian clashes.
I would add that historically, partitioning countries to avoid conflicts hasn't worked out too well. India and Pakistan are STILL mortal enemies and although nobody can be sure for certain, it arguably worsened Hindu-Muslim relations across the subcontinent. Three wars have been fought and the countries still threaten to go to war at any time. Plus, Pakistan is a mess largely because of the legacy of the partition; they were economically devastated, with massive refugee populations and no institutions except for the army (all the rest went to India).
Ireland's another great example. And I would argue that the Western powers should have done more to prevent Yugoslavia's breakup. Milosevich was a thug, but the all-Yugoslav government was led by a moderate Croat and it's important to remember that as thuggish as Milosevich was, the violence started AFTER Croatia and Slovenia declared independence. Had the Western powers made clear that they did not support the breakup of Yugoslavia and instead brokered a compromise plan for a confederal Yugoslavia (as many experts say was possible), the bloodshed could have been avoided and ALL of Yugoslavia could have entered the EU 2 years ago, not just Slovenia.
I'll cite a good interview on the subject of partitions and secessions from Peace Magazine (1995):
Secession and its outcomes:
A conversation with Robert Schaeffer that Quebecers should read
Metta Spencer (interviewer)
METTA SPENCER: Back in September of 1991 we reviewed your book, Warpaths: The Politics of Partition (New York: Hill and Wang, 1990). Since then it has become even more relevant, with the secessionist wars in the former Yugoslavia and the former Soviet Union, and with the prospect of secession in Canada. I think that everybody in the world ought to read your book, but since not everyone will, I'd like to discuss your findings.
ROBERT SCHAEFFER: Okay. The book looks at what has happened in countries that were divided by the great powers after World War II, such as Korea, China, Vietnam, India, Palestine, Cyprus, Germany, and Ireland, which was divided after World War I. The intellectual questions were: Why did they decide to divide these countries? Was partition a good idea? Did it work? What were its consequences? The main reason for partition was to try to settle disputes between contending political parties that wanted state power on their own. In Korea there were Communists and non-Communists; in India there were Hindus and Moslems. When the war ended and independence seemed likely, instead of awarding state power to one group or the other, the great powers decided to split the difference and award state power to both by dividing those countries in two.
They thought that partition would solve the problems between these contending groups, which would then leave each other alone.SPENCER: Famous last words!
SCHAEFFER: Exactly.
Instead of solving problems, partition actually created three major problems that the people who divided these countries had not expected. First, partition was enormously disruptive socially. It led immediately to widespread migrations between two countries. For example, tens of thousands of people migrated across the new Irish borders. In Korea and Vietnam, hundreds of thousands, if not millions, migrated across the borders very rapidly. Seventeen million people migrated across the Indo-Pakistani borders in a six-month period, in history's fastest migration. Many people, fearing for their lives, fled across the borders. Others were told by the governments, "You should live where you're supposed to"--Communists in the Communist part, capitalists in the capitalist part, Muslims in Pakistan, and Hindus in India. People left behind families, businesses, and the graves of their dead ancestors. These migrations often led to war between migrating groups, so that millions of people died in the violence. None of the people who divided these countries expected that people would move in such large numbers.
But even so, large numbers of people stayed behind. For example, there are as many Muslims living in India today as in Pakistan. In Israel, many Arab Palestinians remained and when Israel occupied the West Bank in Gaza, Israel incorporated even more Palestinians. Many Catholics stayed in Northern Ireland, and many Protestants in the South. So there were large residual minorities living in these countries that were divided. The second major problem of partition was that most of the governments in the divided states tended to discriminate against people not their own. In Communist countries they discriminated against capitalists. Communists prohibited the formation of political parties, threw opponents in jail, refused to let them serve in the army, and so on. In countries divided along ethnic lines, the government typically prohibited minorities from serving in the civil service. They refused to let them speak their languages, practise their religion, serve in the army, or vote. Where they did let them vote, they tried to gerrymander the electoral ridings. This discrimination antagonized these minority groups, who have friends in neighboring states.
SPENCER:
Does discrimination get worse after partition than it was before?SCHAEFFER:
Generally it does. If you look at the Koreas, both North and South, they were run by dictatorships that discriminated against everybody, but especially against certain groups. In North Korea, they obviously discriminated against capitalists more and in the South against the Communists. The minorities experienced greater disadvantage, had friends and relatives next door who sympathized with their plight and supported them. That nationalized the political struggles in each country.
SPENCER:
So what previously had been a civil war turns into an international war.SCHAEFFER: Right. A good example would be Korea. The Communists in the South began to rebel against the leadership there. They drew in the Communists from the North so that what was essentially civil war became international. The same with North and South Vietnam. It actually started as a local or domestic civil war but expanded.
That leads us to the third major problem of partition: Most of the states did not like the way that they were divided or the fact that they were divided at all. If you look at their constitutions, most of them claim the right to rule the other half of the country. For example, the South Vietnamese and North Vietnamese constitutions make overlapping territorial claims. So do each of the Irish, German, Chinese, and Taiwanese constitutions. Often they tried to resolve the problems of migration, discrimination, conflicts over who gets what, by going to war with each other. The history of divided states is bad with regard to war: the Korean war, the war between North and South Vietnam, a number of different conflicts between Taiwan and China, three major wars between India and Pakistan, and five Arab-Israeli wars.
SPENCER: Wars over the disputes about which they'd been fighting before separation was imposed as a "solution"?
SCHAEFFER: There had been conflicts in most of these regions but most were rather small conflicts involving guerrillas or riots in the streets.
But once they became states, and they purchased tanks and airplanes, their wars became big. The exception is China, which had a really big war between the Communists and Nationalists before division. Partition actually reduced that conflict--mostly because the Taiwanese were set up across a body of water, the Taiwan Straits, which made them hard to get to. Otherwise, the Chinese probably would have managed to go on fighting.
<snip>
SPENCER: I know of researchers who say that new sibling states are less democratic and economically weaker than before their partition. Do you agree with that?
SCHAEFFER: Economically they are generally weaker than they would have been, but there are exceptions. With outside assistance, South Korea and Taiwan did develop and maybe they are perhaps better off. But not Vietnam.
SPENCER: One hears about Czechoslovakia, that the Czech side is benefiting by casting aside the poorer Slovakia.
SCHAEFFER: In some cases downsizing benefited one but not the other--Taiwan, say, but not China.
SPENCER: In Russia everybody now recognizes that breakup of the Soviet Union was an economic disaster. There's move to reconstitute it, leaving out the Central Asian republics that would be a drag on the economy.
SCHAEFFER: The early partitions did not have so many economic effects but they did have social disruptions because of the migrations. Contemporary partitions create some migration too--notably across the Soviet Union--but the greater disruption is economic. They are breaking up centralized power structures, as well as train lines and supply relationships that were economically integrated. The British Empire didn't integrate economies as much as the Russians.
But you also asked whether secession results in less democracy. Generally it does. Conflict with their neighbors makes the successor states a little crazy.
Officials go into bunker mentality--a military mode of dealing with these problems. The two Koreas both became dictatorships for a long time. However, Southern Ireland is a fairly democratic country. Also Israel--for the Israelis but not the Palestinian Arabs in the West Bank. India is a pretty democratic country for some people, but not for people in Kashmir and Punjab. So you have democratic states with civil wars along their borders.
Is that all attributable to partition? It partly reflects political ideologies and events preceding partition. The Communists in North Korea, North Vietnam, and China stayed as they were before partition. Separation was not the reason for dictatorship there. On the other hand, the long-lasting dictatorships in South Koreas and Taiwan probably reflects the fact that they were divided. Since the partition of Czechoslovakia three years ago, there has been a rise of authoritarianism in Slovakia. Some Soviet Republics have become authoritarian or have reverted to it.
http://www.peacemagazine.org/archive/v11n3p12.htmSchaeffer does note that some secessions and partitions may be justified or unavoidable. I agree - my sentiments against such partitions aren't absolute. But they're VERY difficult to make work, particularly when imposed from an outside group. And they're usually disruptive even when they come from below, which you can see in both Yugoslavia and the Soviet Union.
Now, IF we can put together a coherent plan to divide Iraq into three states, it could be better off, but given how little control we have of the country as is, what makes you think we'll be able to coherently put together a plan that will lead to 3 ministates living in peace and harmony? Most likely it'll lead to even more bloodshed and violence as countries try to expel "foreign" populations and each country tries to maximize territory. And the economic effects will be huge. Granted, Iraq is a mess economically right now as well, but there's even less of a potential for it to repair in the long-term if the networks created over 80 years are thoroughly destroyed.
Not to mention, how do you restrain the Kurds, prevent the disaffected Sunni statelet from falling to fundamentalists? (The Sunnis were largely secular, but extreme times lead to extreme politics and the Islamists will probably be the beneficiaries.) How do you prevent the Shia state from becoming an adjunct of Iran?
Perhaps partition will happen on its own; but it's hardly a desirable outcome and it's in many ways a cop-out option that will likely fail to improve things, based on historical experience.