Reflections on the unity of knowledge were widely expressed at different times in history. They started with the philosophers of antiquity, and then continued in the Middle Ages, during the Enlightenment, in the theoretical foundations of the mereology of systemic thought and also throughout the philosophy of science. Debate on the theme was intensified in the sixteenth century and later with the revolutionary ideas of German, French, English and Italian thinkers about knowledge and the scientific method that will give rise to modern science; for example, Francis Bacon, Galileo Galilei, René Descartes, Blaise Pascal, John Locke, Isaac Newton, Gottfried W. Leibniz, David Hume, and Immanuel Kant. Table 1.1 shows how the ideas of such thinkers intersect throughout time.

In the wake of modern science, however, the issue of disciplinary specialization has emerged, causing a profound change in the search for scientific knowledge. The new order of increasingly specialized disciplines negatively affected the integrated view of science and knowledge, as it kept a distance from the various realities found in the same problem or circumstance and even disregarding the necessary integration between different types of knowledge. Upon realization of this trend, numerous movements and initiatives emerged out of the concern for the breakdown of the unity of knowledge. The Enlightenment philosophers, for example, organized the Encyclopédie or Dictionnaire Raisonné des Sciences, des Arts et des Métiers (Diderot and D’Alembert 1751–1772; Encyclopedia, or a Systematic Dictionary of the Sciences, Arts, and Crafts), a collection of 17 volumes, released between 1751 and 1772 in order to gather, organize and disseminate the knowledge available. Despite this grand undertaking, science has been fragmented, and this situation remains until today.

In the 1990s, however, the debate on the importance of pursuing the unity of knowledge was rekindled, enhanced by the concept of transdisciplinarity, introduced in the 1970s. It was argued that the traditional mode of knowledge production (Mode 1) gave way to a new way (Mode 2) that was more suited to capturing the complexity of reality through scientific research.