World politics change quite dramatically after 1945 although we are still in the middle of the transition to something else, which as of 2017 is still unclear. But we can certainly say that the dropping of the atomic bomb on 6 August 1945 transformed the idea of power as well as the idea of the nation-state. It was not an obvious transformation--indeed, there were many in 1945 who believed that the atomic bomb was just another weapon. But as nuclear military power evolved, particularly after the development of Intercontinental Ballistic Missiles (ICBMS) in the early 1960s, we slowly began to understand that the nation-state could no longer offer an iron-clad guarantee of security. That guarantee was part of the contract between states and citizens: the state would offer security, and citizens would give their loyalty to the state.

But nuclear weapons altered that contract. The absolute best that nation-states could offer was the ability to deter a nuclear attack. An opponent armed with nuclear weapons and ICBMS could obliterate a nation if it so chose and there was nothing a state could do to to prevent that catastrophe. All it could do in response was to threaten the mutual obliteration of its opponent (thus, the doctrine of Mutual Assured Destruction [MAD]). There is currently an effort to bring back a guarantee of security through an Anti-Ballistic Missile (ABM) system, but that effort is roughly equivalent to shooting a bullet to hit a bullet. The current technology is far from fail-safe.

Nuclear weapon also, therefore, made war especially dangerous. It was no longer simply an instrument of diplomacy. Through miscalculation or through escalation even small wars could bring about widespread destruction. The phrase used by strategists to describe war-making in the presence of nuclear weapons was: "We make war in the nuclear age the same way porcupines make love. Very carefully"

The dangers of war also complicated the role of the United States as it emerged as a dominant force in world politics. Unlike previous hegemons, the US did not insulate foreign policy from the democratic process. Previous hegemons had conducted foreign policy with little attention to citizen input. Most citizens had few methods of obtaining information about other countries until technology made information more immediate in the 20th century, and thus had little leverage over foreign policy. The US commitment to democracy, typified most dramatically by its reliance on the draft to field an army (it was not until 1973, in the midst of the Vietnam War, that the US switched over to a volunteer army), made citizen input into foreign policy inevitable. In order to justify its activities abroad, the US needed to gain the support of its citizens for such efforts. It was unlikely that citizens would support classical realist justifications for war (can one imagine the US invading Iraq in 2003 by simply asserting that it wanted Iraq's oil?), so US foreign policy revived an old doctrine justifying war. We call that doctrine the Just War Doctrine.

The Just War Doctrine is not international law and we should not think about it in legal terms. Rather, one should think about the Just War Doctrine as a checklist: does the decision to go to war and the way the war in conducted conform to generally acceptable moral precepts? This injection of moral considerations into foreign policy was in many respects a repudiation of classical Realpolitik.

These moral considerations parallel traditional realist thought. Nation-states still follow their national interest, but they now must craft those interests in language that conform to moral principles: "spreading democracy", "upholding international law", "protecting innocents". The need to develop a new rhetoric of world politics complicates decision-making to an incredible degree and makes the role of being an analyst much more difficult. It is almost like living in two separate universes and it is very difficult to figure out exactly why a state is following a specific policy. That new rhetoric has been turbo-charged by the proliferation of news outlets and social media. We have access to significantly more information but also have significantly less confidence in the reliability of that information.

The dramatic change in the number of nation-states after the Great European War also made world politics more complicated. In 1945, 44 nation-states signed the UN Charter, there are now 194 nation-states. These new states were created through the collapse of the European empires through the process of decolonization. Unfortunately, these new states kept the territorial boundaries of the old colonies and most of those boundaries reflected only the interests of the colonial powers and not the interests of the people who actually lived on the ground.

Indeed, there are about 2,000 groups of more than 100,000 people who regard themselves as "distinct" from others. The distinctiveness of these groups is variously determined. It could be determined by religion, or by ethnicity, or by race, or by any number of criteria that are regarded as important.

Thus, the world has a major problem. There are about 2,000 nations in the world and only 194 states.

Many of the conflicts in the world revolve around this discrepancy. For example, the Kurds regard themselves as a separate nation, but Kurds live in 4 states: Iran, Iraq, Syria, and Turkey. The creation of a Kurdish nation-state would mean that four states would have to be carved up. No state will allow the loss of territory. Territory is the sine qua non of a state. Thus, all four of these states have very difficult relations with the Kurds, with the Turks actually conducting a war against Kurdish separatists. At the other end of "nationhood", Arabs constitute a clearly identifiable nation. But Arabs live in 26 separate states.

When Yugoslavia fell apart, the Serb nation and the Croat nation endeavored to create their own states, both at the expense of the Bosnians. The resulting violence led to 400,000 deaths and over 100,000 rapes. In 1994, the Hutu and the Tutsi in Rwanda fought a ferocious war that killed 800,000 people in six weeks. We can go on and on with unfortunate examples of nations aspiring to become states. There are no guidelines in world politics to manage this type of transition. The best the world can do is to say: If your nation wins the war, then it can become a state. That principle is itself a stimulus toward conflict.

Thus we confront a very difficult discussion topic: Has the world since 1945 become ungovernable? Are there any reasons to believe that the world can move to greater stability in a more peaceful, disciplined manner?