Platonic Ideal vs. Cartesian Reality: A Philosophical Comparison
Platonic Ideal: According to Plato’s ontological dualism, true reality exists at the intelligible level, which is universal, necessary, and immutable. The sensible world is a secondary consequence of the intelligible realm.
Descartes’ Perspective: Descartes distinguishes three types of realities: the world, human beings, and God. The world is composed of extensive substances, including the human body. Descartes gives the physical world a reality that Plato did not fully recognize. For Descartes, the real world is not merely the material world, but the “world of physical science” where everything can be mathematized.
Knowledge and Truth
Plato: For Plato, the sensible world offers only a possible view, not true knowledge. The sensible world is useful for recalling ideas that the rational soul knew before incarnating in the body (nativism). The truth of knowledge depends on the truth of things (objectivism), which comes only through the rational soul. The senses show only an apparent reality (rationalism).
Descartes: Descartes agrees with Plato in asserting that the highest knowledge is intelligible science. Like Plato, he considers beliefs and opinions worthless. He cautions against relying on the senses as a valid source of knowledge, asserting that reason is the only reliable source. Descartes also accepts the existence of innate ideas but recognizes adventitious and factitious ideas as well.
Subjectivism vs. Objectivism
The greatest difference between Plato and Descartes lies in their commitment to subjectivism, a hallmark of humanism and anthropocentrism. Descartes posits that the subject determines when knowledge is true. Plato’s approach is objectivist: knowledge is true if it is knowledge of ideas, the true forms. For Plato, the object known is key, whereas for Descartes, it is the subject.
Anthropological Dualism
According to Platonic anthropological dualism, the true identity of man is his soul. The rational soul is immortal and the source of true knowledge. To achieve this, one must fight the body and senses, making life a process of separating from the sensible.
Descartes’ anthropological dualism is similar to Plato’s. As in Plato, the soul is immortal and defines humanity.
The Tree of Science and Morality
Descartes’ project, as outlined in his discourse, aims to use reason to find truth in science. In establishing the “tree of science,” he places morality as the highest branch. The goal is to develop a morality based on certain principles, echoing Plato’s thought where the ultimate goal of the philosopher is to find the good and live accordingly.
Modernity, Individualism, and Human Rights
The separation of reason and faith has led to the development and mathematization of science, as well as the emergence of atheistic and agnostic positions. According to Descartes, reason leads to the knowledge of God. However, modernity has lost its rationalist optimism; modern individuals no longer believe that reason is powerful enough to clearly demonstrate the existence of God, resulting in an agnostic rationalism.
The Thinking Subject
Descartes asserts that the “thinking” subject is the criterion of truth. This statement has had profound consequences in the history of thought. Descartes advocates not relativistic subjectivism, but rational subjectivism. Reason is the same in all individuals, laying the foundation for individualism, critical to modern society, and the demand for equal rights for all human beings.