Martin Heidegger and René Descartes are pivotal figures in [[Philosophy]], but their approaches to understanding being, existence, and the world diverge significantly. Heidegger was critical of Descartes’ approach, particularly as outlined in Descartes’ _Meditations on First Philosophy_, which introduced a framework that prioritised rational certainty and the separation of mind and body. **Descartes: Dualism and Foundationalism** René Descartes (1596–1650) is best known for his method of radical doubt, leading to his famous conclusion, _cogito, ergo sum_ (“I think, therefore I am”). This established the [[Thinking]] subject (_res cogitans_) as the foundation of all knowledge, separating it from the external, extended world (_res extensa_). Descartes’ [[Dualism]]—dividing reality into mental and material substances—became foundational for modern [[Science]] and philosophy. **Heidegger’s Critique of Descartes** Heidegger, writing in the 20th century, challenges Descartes’ framework, particularly in _Being and [[Time]]_ (1927). His critique focuses on several key areas: 1. **Reduction of Being to a Subject-Object Dichotomy:** Heidegger argues that Descartes reduces the understanding of _being_ to a relationship between a subject (the thinking mind) and an object (the external world). This dualism neglects the richer, more fundamental question of what it means _to be_—a question Heidegger seeks to recover. Heidegger contends that Descartes’ approach artificially separates humans from their world. Instead, Heidegger introduces the concept of _[[Dasein]]_ (literally “being-there”), which emphasizes that human existence is always already situated in and engaged with the world. For Heidegger, we are not detached observers but beings deeply entwined with our environment and [[History]]. 2. **Prioritisation of Rational Knowledge:** Descartes’ method elevates rational, scientific knowledge as the ultimate way of understanding reality. Heidegger critiques this as overly narrow, sidelining other modes of relating to the world, such as practical engagement or historical context. For example, Heidegger discusses tools: we do not primarily encounter a hammer as an object to be observed (as Descartes might suggest) but as something _ready-to-hand_—understood through its use. 3. **Mathematical-Scientific View of the World:** Heidegger argues that Descartes’ philosophy contributed to the dominance of a mathematical and technical worldview, where [[Nature]] is seen as something to be measured, controlled, and exploited. Heidegger critiques this as emblematic of the modern forgetting of _being_—what he calls _Seinsvergessenheit_. 4. **Neglect of Temporality and Historicity:** For Heidegger, Descartes’ emphasis on the thinking subject overlooks the temporal and historical nature of existence. Human beings are not static entities but are defined by their temporality—the way they project themselves into the future, interpret the past, and live in the present. Descartes’ philosophy, Heidegger claims, abstracts humans from this temporal and existential context. **Heidegger’s Alternative: A More Fundamental [[Ontology]]** In contrast to Descartes’ focus on [[Epistemology]] (how we know), Heidegger is concerned with [[Ontology]] (what it means to _be_). Heidegger calls for a return to the pre-Socratic understanding of being, which he believes was obscured by philosophers like Descartes who emphasized the subject-object split. For Heidegger, understanding being requires acknowledging our interconnectedness with the world and the temporal, relational, and practical nature of existence. **Summary** While Descartes’ dualism laid the groundwork for modern philosophy and science, Heidegger saw it as a turning point in the alienation of humans from the question of being. Heidegger’s critique goes beyond philosophy to address the broader implications of Cartesian thinking in shaping modernity’s instrumental relationship with the world—a theme central to his later works on technology and ecology. `Concepts:` `Knowledge Base:`