Although a certain degree of internal inequality among social groups within the same territory, country, empire has existed almost everywhere in history, the phenomenon of international inequality is relatively recent and at the same time has established itself with an uncommon speed and breadth. While the authoritative economics historian Paul Bairoch reported in his texts that the income and wealth imbalances between the great international social groups were still reduced in 1700 (with approximate ratios of 3 to 1), the UN has published studies that show the growth of global inequality between the richest 20% and the poorest 20% of the planet (still 3 to 1 at the beginning of 1800, but reached 72 to 1 at the end of 1900).
Political-economic colonialism in Africa and Asia at the end of the 1800s and the beginning of the 1900s, and economic neo-colonialism in the second half of the 1900s (which, although without military occupation, takes value from the African, Asian and Latin American peripheries, for example through the mechanism of external debt) are the factors that best explain the growth of international inequality.
For a long time, these analyses have remained the heritage of Third World circles and intellectuals from those geographical areas. However, the ideas of equity and equality seem to be innate in human beings, as confirmed by research which shows that even very young children are aware of inequality. And so, since the late 1900s and throughout the 2000s, the emergence of international movements, the global economic crisis and the great success of the book Capital in the Twenty-first Century by Thomas Piketty have increased the interest of the global community in a theme which for decades had continued to exist without receiving attention.
Studying these fundamental dynamics to understand the overall planetary situation, analysing their historical, geographical, economic, environmental, political and cultural implications, making hypotheses on their possible solutions and trying to implement them is a task that even today too few subjects have assumed. Schools can play an important role in ensuring that this issue receives the importance it deserves and that future citizenship be provided with the tools to design and live in a world that should be more sustainable, fairer, more cohesive, and consistent with the objective (SDG) 10 of the UN Agenda 2030: "Reducing inequalities within and between countries".
