How does Dasein differ from Descartes’s idea of a thinking subject?

Martin Heidegger developed the concept of Dasein to fundamentally challenge the Cartesian view of the human individual as a "thinking subject."

In the tradition of René Descartes, humans are defined as minds or souls radically distinct from the material world. This mind-body dualism creates a cognitive isolation, where the subject must use internal mental states to represent or bridge the gap to an external world.12

Heidegger rejected this model, arguing instead that:

• Being-in-the-world: Rather than being a mind sealed off from reality, the individual is inherently "in the world." Dasein is not a mental construct but a unitary existence.1
• Disclosive function: Dasein acts as the "there" or the locus where entities show themselves. It does not need to "represent" the world because it is already engaged in the mode of uncovering it.1
• Holistic nature: Dasein is a whole individual, not a compound of mind and body. By replacing "consciousness" with Dasein, Heidegger moved away from sequestering human functions into a mysterious, internal mental compartment.1