Alfred Schütz and Talcott Parsons, two towering authorities of Weberian social thought are rarely interpreted in the same theoretical perspective (with the exception of Harold Garfinkel). This article intends to show that Schütz’s later writings about the constitution of social reality in the pluralized and differentiated modern society and Parsons’s concept of the social system converge with reference to their common problem of understanding interaction. In this article, I use Ronald Laing’s psychiatric thought of the early 1960s as a starting point to discuss some of the points of intersection between Schütz and Parsons. Laing argued that psychosis is not a phenomenon of the individual mind. Rather it must be understood in terms of an interaction system that is constituted by doctor and patient. The patient cannot maintain ego borders strong enough to establish a role-based social relationship and feels ontologically insecure. It is necessary to understand the patient in his existential position which constitutes his self as a kind of role. Schütz and Parsons reflected on similar interaction systems. Schütz analyzed the little social system that is established between Don Quixote and Sancho Panza; Parsons addressed the social system between doctor and patient. It is argued that Schütz and Parsons analyzed the conditions under which a social system can be established, but they also look at its breakdown leading to the situation as described by Laing.