According to Wittgenstein, “the limits of language mean the limits of my world”. In this sense, categories shape the world they set out to understand. For this reason, and since the way we conceptualise the world influences our perception and comprehension of the context we live in, scholars have the duty to use proper concepts to describe reality. Especially in times of legitimacy crisis and scepticism, addressing good definitions and accurate descriptions can be helpful to rationalise and understand complex issues. In particular, one of the hardest challenges of the last decades for legal philosophers concerns the analysis of the international legal order’s development through categories and paradigms. Mostly, the biggest problem to solve has always been the relation between the national legal order and the international one. In fact, since States decide to cooperate or at least to recognise other States’ sovereignty, they accept some limitations to their own sovereignty. This point poses serious consequences, which progressively became even more evident in the process of European integration. The aim of the paper is to highlight the importance of a pluralist approach towards the European Union in order to understand its values and purposes, the way it operates and the idea of international relations that it proposes.