What are we talking about when we talk about inequality?
Inequality between whom?
Inter-country inequalities/intra-country inequalities
Inter-country inequality refers to inequalities in wealth or well-being between different countries in the world, while intra-country inequality refers to inequalities within a particular country. Inter-country inequality has largely decreased over the last 30 years due to globalization and the rise of China since the 1980s and of countries such as India, Vietnam and Indonesia in the 2000s. This reduction in inter-country inequality has at the same time been helped by low growth in high-income countries. On the contrary, intra-country inequality has increased considerably over the last thirty years, as globalization has created winners and losers within each country.
Vertical inequalities / horizontal inequalities
Vertical inequalities are related to the distribution of income between different social groups, whereas horizontal inequalities correspond to the distribution of opportunities and constraints within social groups with a common identity (e.g. inequalities related to gender, generation, location, religion, ethnicity).
Inequalities of what?
Inequalities of opportunity/inequalities of outcome
Although these two types of inequality are often linked (inequality of outcome often being the result of inequality of opportunity), policies aimed at tackling inequality of outcome can harm inequality of opportunity, and vice versa.
Inequality of rights
Although equality in law is universally enshrined, it does not necessarily result in equality of opportunity. For example, education for all is a universal right, but in reality many children are not enrolled in school, which diminishes equality of opportunity.
Income inequality
Income inequality is the type of inequality on which most research on socio-economic inequality is based. However, the study of this type of inequality has limitations because income inequality does not take into account the process and determinants of these outcomes.
Absolute inequalities/relative inequalities
While absolute inequalities correspond to the absolute distance between two situations, relative inequalities allow us to determine how one result relates to another.