It is a century from now, maybe two. The most horrific war to ever touch the world has ended, the forces of justice and equality barely prevailing over the servants of avarice and despair. The price, however, was terrible. Cities lie in ruins, poorer regions obliterated by the machine hordes of the super-rich, affluent regions torn down by rebel incursions. From a peak of ten billion people, the war has dwindled the population down to maybe a billion or two. Billions died from combat, heat exhaustion, exposure, disease, assassinations, starvation.
The survivors face the daunting task of rebuilding civilization, but it can not be like it once was. Technology and knowledge have survived the apocalyptic war due to the foresight of many individuals, as well as neutral nations such as Switzerland and the Nordic countries that will be untouched by the war because the wealthy of those nations chose to change their ways rather than share the fate of greedier countries. Today we already have seen the efforts of those dedicated to preserving knowledge and progress. Sites such as Wikipedia continually add more and more to their database. And while the veracity of these articles needs to be validated through multiple sources before they can be accepted as fact, most of them are on the level. Projects such as the Svalbard Global Seed Vault will ensure that crops survive any disaster that arises; the stored seeds will be used to restore plants wiped out in the War. A vault storing the genetic codes of countless extinct animals will also be used to repopulate the ruined Earth once humanity has repaired it. Other measures will be taken to preserve knowledge and technological progress, to be used at the proper time. But first, Earth has to be restored.
I'm going to assume an absolute worst-case scenario, short of human extinction. Most countries are in ruins, their infrastructures broken beyond repair. Cities are ghost towns, electrical power is gone for most of the world, and very few nations have been untouched by war. Coal and oil reserves have all but run out. However, there are some countries that have survived intact. Much of Europe will actually survive the war relatively unscathed, due to relative income equality and pervasive social nets in many of its nations. Great Britain and Portugal will fall, as well as Bulgaria and some of the Balkan states. Many southern European nations will have to be abandoned due to worsening drought conditions until crops able to withstand the new temperatures and reduced rainfall are engineered. This will cause a growing refugee crisis in northern nations, but one that will be alleviated with increasing arable land in the far north, as well as the prevalence of urban farming. Africa, Russia, the United States, China, as well as most of Asia and South America will collapse due to a combination of worsening climate conditions and class warfare. Most survivors in the Western Hemisphere will flee to Canada, the only nation in the Americas that will survive the war. Many Asian survivors will create new nations out of the ruins of Russia. Siberia will become one such nation. Others will flee to Australia, untouched by the war due to preemptive social reforms and its geographical position. Some intrepid survivors from around the world will even flee to the thawing Antarctica, and create the new nation of West Antarctica.
Most of the new societies will have learned well the lessons of the past. Very few will retain the old survival-of-the-fittest capitalist system. The new business system will most likely be a communist-capitalist hybrid, while the political system will be either a meritocracy or a demarchy/lottocracy. Oligarchies will be rare. Even if I'm wrong, and the new nations go right back to the old ways, this will simply cause another catastrophic war a couple of centuries later. Either way, sooner or later humanity will get the message that a more egalitarian system is needed, and they will adopt such a system.
The system of education will be rebuilt from the ground up. Teachers will be evaluated based on the effectiveness of their teaching, rather than tenures or unions. They will be part of Education Councils, which will ensure they get fair compensation while at the same time being held accountable by their peers. Ethics Officers will oversee the Councils to prevent corruption. All children, from kindergarten through graduate school, will be taught every subject — law, business, political science, chemistry, biology, physics, basic and advanced mathematics, foreign languages, geology, geography, astronomy, quantum mechanics, computer coding, robotics. Education through the PhD level will be compulsory, while at the same time taking into account a student's interests and strengths. A writer will not be required to get a PhD in neurology, though advanced science courses will still be required. Students who struggle will be assisted with tutors as well as treatments designed to enhance cognition. Education will be funded through taxation, even graduate school. Humanity will become a species of geniuses, through genetic and technological augmentation and a focus on education rather than wealth.
And it is these many geniuses who will create innovations that will change the very fabric of the world, as well as humanity itself...