This article comprises several sections. The first is devoted to an explanation of a number of notions stemming from work by Ilya Prigogine and others on open systems far from equilibrium. As a result of this work, I have been able to stand back from the traditional approach employed in family therapy, that of open systems at equilibrium (the theory of Ludwig Bertalanffy). The second section describes a clinical example based on elements close to Prigogine's theories. In the third part I develop an approach that—although continuing to draw on Prigogine's work—is much more closely linked to the research I have carried out with Félix Guattari over recent years. In this part I attempt to study a level that, in my view, has too often been left outside the field of inquiry: that of couplings between “singularities” of members of the family system and the therapist. A clinical case is presented in which this “semiotic” level, as Guattari terms it, is used together with that of the “intrinsic rules” of the system. Finally, I propose a few avenues of inquiry and research on the basis of the concepts presented.