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resorting to teleological or metaphysical explanations. However, in studying the relationship
between body and soul, Descartes faced a particular problem: the soul is not governed by
mechanical laws. While the body, as an extended substance, follows the laws of physics, the soul,
as a thinking substance, operates independently. His solution to this dilemma was to recognize
that body and soul are distinct substances; therefore, the soul is not subject to mechanical laws.
The next Cartesian question was how both substances are integrated into a single
individual. Descartes resolved this through a third substance, a "miracle" that allows for the
communion of body and soul despite being different substances, which Descartes calls "God"
(Descartes, 2014). This miracle manifests itself in the pineal gland, which Descartes identified as
the point of interaction between body and soul. Contrary to this perspective, Baruch de Spinoza
proposes that the supreme reality is a unique manifestation of God; the universe, deity, and nature
are the same entity expressed in different ways. According to Spinoza, there is no plurality of
substances; instead, thought and extension are two attributes of a single substance, and these
attributes are part of the totality of nature and being (Spinoza, 1663).
For Spinoza, everything that exists is an expression of God, and the differences we
perceive are simply modes of a single infinite substance. His pantheistic and monistic view
contrasts deeply with Cartesian dualism, offering a unified perspective of reality in which there
is no separation between mind and body, but rather an essential interrelationship of all things in
God. Descartes and Spinoza represent two fundamental approaches in modern philosophy
regarding the nature of reality and the relationship between mind and body. While Descartes
introduces a dualism that separates the mental from the physical, Spinoza proposes a monistic
view in which everything is part of a single divine substance. Both approaches have had a lasting
impact on philosophy and continue to be crucial reference points in contemporary debates about
the nature of reality, consciousness, and the relationship between mind and body. Descartes' and
Spinoza's rationalist ideas laid the groundwork for Immanuel Kant to develop his philosophy of
transcendental idealism (Dilthey, 1949).
Descartes, known as the father of modern rationalism, argued that the certainty of
knowledge comes from reason, not from the senses, and that the physical world exists as an
extensive and finite substance, independent of our consciousness (Descartes, 1641). Spinoza, in
his Ethics, posited that everything that exists is part of a single divine substance, identified with
God or Nature, and that mind and body are two attributes of this substance, an attempt to resolve
Cartesian duality between mind and body (Spinoza, 1677). Immanuel Kant, inspired by these
rationalists, proposed that reality, in terms of space and time, does not exist independently of the
human being; instead, they are forms in which we perceive objects. According to Kant, objects in
space and time are mere representations and do not exist outside our ability to represent them.
With this perspective, Kant argues that things exist, but our perception of them is entirely different
from their true nature, the "thing in itself," which is impossible to fully know (Kant, 1757).