How does Heidegger’s view of human beings challenge the idea of a private inner mind?

Martin Heidegger challenges the traditional Cartesian view of the human being as a "thinking subject" or a private, isolated mind by introducing the concept of Dasein, or "being-in-the-world".12

From the time of René Descartes, philosophy often treated the mind as an internal domain—a "specially designed compartment"—that represents the world to itself while remaining cognitively sealed off from it. Heidegger rejects this, arguing that there is no need for internal mental states to mediate a relationship between the individual and the external world.12

Instead, Heidegger posits that human existence is fundamentally unitary. By defining humans as Dasein ("being there"), he suggests that we are inherently "in" the world, serving as the locus where entities disclose themselves. This perspective effectively dismantles the notion of a private inner mind from which others are excluded. Rather than sequestering human functions within a mysterious mental interior, Heidegger identifies these functions as the defining characteristics of our existence in the world. Consequently, the distinction between an "inner" subjective mind and an "outer" objective world is replaced by the unified, disclosive nature of Dasein.132