In this book, we have focused on developing an understanding of the scope of complexity theory and its application to criminal justice and social work (and beyond). The various chapters, while representing an exposition of some of the defining features of complexity, also demonstrate that these features are given different interpretations or levels of significance depending upon whether you are looking at this from a positivist, post-positivist or constructivist position; and even then, these positions have philosophical and theoretical differences within them. It can appear that the study of complexity is very complex; however, what this book does demonstrate is that differing ontological, epistemological and methodological traditions are open/sensitive to complexity, albeit in ways that tend to fall along the traditional fault lines of the ‘natural’ and ‘social’ sciences. However, the very fact that complexity is being studied across the sciences, social sciences and in social theory, and with some broad areas of consensus, should be enough to refute any fundamentalist charges of physics envy/grand theorising on the one hand, or accusations of soft science on the other.

The particular challenge that complexity theory poses involves the application and analysis of whole-systems thinking for our particular theoretical position, and especially in relation to human systems. The universal cosmos is, of course, the ultimate fractal, comprising evolving constituent systems – so much for the nature of galaxies as self-organising systems for example – but what does complexity theory mean for our understanding of human consciousness, the nature of human society and the processes that occur therein? In this sense, the book takes us on a journey from: first, abstract mathematical, mechanical and deterministic concepts in the Platonic, Cartesian and Newtonian tradition(s), and the development of Descartes's ‘ghost in the machine’ idea to accommodate human consciousness in the clockwork universe; to, second, what would appear to be a more human(e) approach through the Aristotelian, Marxist, existentialist, postmodern tradition(s), focusing on the primacy of human experience, learning and the nonreducibility of evolving and complex human life. It is also important to note that quantum mechanics arises from the positivist tradition but radically changes our understanding (if the Copenhagen Interpretation is correct) of the nature of mind–matter interaction.