Individuals in the Social Lifeworld is an analysis of Dasein's Being-in-the-world by asking how an individual Dasein (a person) interacts with their fellow Dasein (other people). Acknowledging that mineness is fundamental to Dasein, the book's analysis uncovers Being-sphere as the existential place of Dasein that is formed through a person's interactions with and involvements with the world. Being-sphere does not express any form of idealism but is an acknowledgment of what Being-in-the-world means for perception and individual responses to the world. Being-sphere provides valuable tools for social and political philosophy by seeing interpersonal relations as a dynamic interaction of individual Being-spheres (people). Using the concept of Being-sphere in social philosophy explains how a person is embedded in the world and how the world is an integral part of a person. The concept of Being-sphere avoids the problems of the Cartesian subject while at the same time acknowledging the person as a dynamic self-constituting rational and moral agent not wholly determined. It shows how people gain beliefs and use them as the basis for their worldviews and actions. Being-sphere improves Heidegger's concepts of das Man and Befindlichkeit and provides a broader conception of Dasein and its projection into its possibilities. Because it takes seriously Heidegger's observation that subjectivity is the true world of Dasein, it can explain the way that a person encounters and appropriates anything in the world, particularly other people. Being-sphere also explains how people experience and are affected and changed by their experiences, revealing new depths of a person's situatedness in the world and their relationship with society.