The first three decades of the twentieth century saw dramatic changes in science and philosophy. In 1905 Einstein published his special and, in 1919, his general relativity theory, and in 1924 De Broglie formulated the wave-particle dualism for matter – the beginning of quantum theory. At the same time the idealism of the Neo-Hegelian schools, of Bradley, McTaggart, Royce and others, lost its credibility. The idea that the distinction between appearance and reality was philosophically fundamental, the claim that space and time are not real, but a mere appearance, and the associated degradation of all scientific knowledge to knowledge of appearances only, the view that philosophy could deal with a purported reality behind appearances – all these assumptions lost their grip on the minds of philosophers, who instead began once again to recognise the relevance of the empirical sciences.

A. N. Whitehead worked at this time as a philosophically minded Professor of Applied Mathematics at Imperial College London. He reacted very quickly to the scientific developments that he took to require nothing less than a radically new way of understanding nature itself. This book— together with his more technical Enquiry concerning the Principles of Natural Knowledge from 1919—is his attempt to formulate such a new concept of nature against the background of post-Newtonian science and in the spirit of the post-Kantian and post-Hegelian New Realism.

For Whitehead, natural scientists were not being naïve when they took their objects of study to exist independently from thought. But natural scientists do not argue for their realism. It is self-evident, for a physicist who studies the sun or a palaeontologist who investigates a fossil, that they do not create these objects that existed millions of years before any human enquiry was possible. Whitehead tried to take this realism seriously because he accepted the temporal dimensions in which science placed its objects. Thus, the nature that science investigates cannot be just the totality of human experience, organised by laws, as Kant thought. It is more. The fact that the different natural sciences can work together was of great importance for Whitehead, and he thought it set him a philosophical task, that of formulating a generalised and realistic concept of nature. His conclusion was that nature is a ‘self-contained’ totality that is ‘closed to mind.’