Foundations of Knowledge: Skepticism and Rationalism

Skepticism in Philosophy

Introduction to Skepticism

• Skepticism posits that no knowledge is possible.
• It describes a term relationship: one is skeptical about something.
• In epistemology, skepticism denies the possibility of knowing.
• It is ambivalent and anti-philosophical because philosophy is an attempt to learn.
• Philosophy, because it always doubts and rejects unsafe assumptions, has been important in forcing thinkers not to fall into complacency.

Types of Skepticism

• Partial Skepticism: Doubts the possibility of knowing a certain aspect, similar to agnosticism (e.g., it's not possible to know God or beyond the empirical).
  • Difference from Atheism: An atheist claims to know that God does not exist.
• Total Skepticism: Affects all knowledge, implying one cannot even know one's own affirmation.

The Skeptical Argument (Descartes)

• Descartes focused on doubt as a method.
• He was the first modern thinker. Modernity, a time to break with the Middle Ages, begins with the Renaissance.
• Descartes sought a solid foundation for understanding, a method to prevent errors.
• To apply this method, he doubted everything.
• He identified three grounds for doubt:
  1. Senses deceive: We know how things are, not just as they seem.
  2. Inability to distinguish sleep from wakefulness: Dreams can feel real.
  3. Evil Genius: A hypothetical entity that could deceive us even about mathematics.
• Despite these doubts, one truth remains: "I think, therefore I am" (the Cogito).
• This foundational idea leads to clear and fundamental views.

Modern Skeptical Arguments

• Contemporary skeptical arguments often involve:
  • Illusion: The problem of appearance versus reality.
  • Hallucination
  • The Brain in a Vat scenario.

Sources of Knowledge

Rationalism

• Descartes, after initial hesitation, aimed to provide accurate, indubitable knowledge.
• His model was mathematical, seeking necessary universal truths.
• These truths are universal and valid for all.
• Being: What cannot be other than it is; to think otherwise leads to contradiction. Its opposite is contingency.
• Universal and necessary truths are evident.
• The first truth is evident (for Descartes): evidence as a criterion of truth.
• Innate Ideas: Reason itself is the source of these ideas.
• While we can derive ideas from the senses, they are not foundational.

Distinctions in Knowledge

• First Distinction:
  • Truths of Reason: Universal and necessary, valid for all knowledge.
  • Truths of Fact: Derived from experience.
• Second Distinction:
  • A Priori Knowledge: Knowledge independent of experience.
  • A Posteriori Knowledge: Knowledge derived from experience.
• The limits of knowledge are optimally understood by applying all known methods to reality.