Descartes' Meditations: Cogito, God, and Knowledge

Second Meditation: Methodical Doubt and the Self

Applying Methodical and Universal Questions

Metaphysical Discourse: "I think, therefore I am" (Cogito ergo sum). Thought is the first truth, founded on doubt. The edge is the subject "I". This raises the question of the subject of modern critical doubt. The thinking thing is a substance cogitans. Is the relation between thought and body? Thought is essentially res cogitans plus body, which defines us best. The thought is easily guessable: res cogitans plus the self is the simple (one unit, indivisible) whole, contrasting with Hume's view on the existence of the self.

Nietzsche suggests that we do not truly desire what we passionately think we desire. Freud posits that the ego is not only thinking but also unconscious. The idea of division originates from Descartes.

Extension and the External World

Res Extensa (extension) and the outside world are defined by their quantitative properties, not by quality. This reflects Galileo's influence: focusing on properties in terms of nature. Appearance shows why quantitative properties represent reality today, reporting on the nature of reality.

Third Meditation: Rationalism and Proving God

Introspection-Related Rationalism

Reason leads us to look within, rather than solely outside. "Know thyself" (Socrates). By knowing myself, I can trust what reason has demonstrated. If God exists and is not a deceiving genius, then the world cannot be a deception. This demonstrates that when my mind perceives green, it corresponds to an objective reality. Reason, when used properly, is capable of perceiving reality.

The Argument for God's Existence

• I have in my mind the idea of perfection.
• This idea must have come from something actual, as it cannot originate from my finite self.
• Therefore, God exists (The Ontological Argument).

Fourth Meditation: The Source of Error

How We Err in Knowledge

Error is not caused by God, but by a lack of understanding. We err because our understanding is finite and limited. Freedom is the capacity to choose (the will). Freedom could be indifference: if two paths are open, I am indifferent, and then I move toward one or the other.

Mistakes can arise from examining options through my will. Wrong use of freedom occurs when we decide before fully knowing the options.