EPISTEMOLOGY

study of knowledge — how we know what we know.

What is Knowledge?

Knowledge is justified true belief — when you believe something, it is true, and you have a good reason (justification) for believing it.

Rationalism

René Descartes — famous for “I think, therefore I am” and believing in innate knowledge.

Belief that knowledge comes primarily through reason and logic, not the senses.

Empiricism

John Locke — argued the mind is a blank slate at birth.

view that all knowledge comes from sensory experience — what we see, hear, touch, etc.

David Hume — emphasized skepticism about knowledge beyond experience.

Phenomenalism

Objects only exist as sensory experiences; we never know the “thing-in-itself.”

To say “the chair exists” means we have or could have sensory experiences of it.

George Berkeley — argued that to exist is to be perceived (“esse est percipi”)

Common Sense Realism

the belief that the world exists as we perceive it — things are really there just like our senses tell us.

• Thomas Reid — argued against skepticism and said our common sense perceptions are trustworthy.

• If you see a tree, Common Sense Realism says the tree really exists, not just in your mind.

Idealism

belief that reality is fundamentally mental or made up of ideas — the physical world depends on the mind.

• Reality is a collection of ideas or perceptions, not independent matter.

• George Berkeley — famous for saying objects exist only when perceived by a mind.

Representational Theory of Perception

we don’t perceive the external world directly; instead, our mind creates internal representations (or mental images) of objects based on sensory input.

• Descartes — skeptical about trusting senses because they give us only representations.

  Seeing a tree means your brain forms a mental image based on light signals, not that you directly “touch” the tree with your mind.

Solipsism

only your own mind is certain to exist — everything else (people, world) might be just part of your mind or imagination.

• You can only be sure of your own thoughts and experiences.

• Other minds and the external world are not provably real.

Pragmatism

the idea that the truth of a belief depends on its practical effects and usefulness.

• Ideas are true if they work or help us solve problems.

• Charles Peirce — founder of pragmatism, focused on practical consequences.

Skepticism

doubting or questioning knowledge claims — not accepting ideas without good evidence.

• David Hume — questioned knowledge about cause and effect.

• René Descartes — used skepticism to find what could be known for sure.

Deconstructionism

way of analyzing texts and ideas to reveal hidden meanings, contradictions, and assumptions — showing that meaning is unstable.

• Jacques Derrida — founder of deconstruction, focused on language and philosophy.

A Priori vs. A Posteriori Knowledge

• A Priori: Knowledge that is independent of experience (e.g., math, logic).
  
  Knowledge you have before or independent of experience.

• Based on reason, logic, or definitions.

• A Posteriori: Knowledge that depends on sensory experience (e.g., science, observation).

• Knowledge you gain from experience or observation.

• Based on sensory evidence.

• Immanuel Kant explored this distinction deeply in his work.

 Cogito Ergo Sum (“I think, therefore I am”) — Descartes

meaning that the very act of thinking proves your own existence.

• You can doubt everything — the world, your body, other people — but you cannot doubt that you are thinking.

Edifying

educational or uplifting — it improves your mind or character by teaching you something valuable or inspiring.

• Edifying actions or ideas help people become better, wiser, or more virtuous.

Unity of Consciousness

The idea that all our thoughts, feelings, and experiences are connected and experienced as a single, unified “self”.

• Immanuel Kant emphasized the unity of consciousness as central to how we experience the world.

Casuality

Causality is the idea that every event has a cause — one thing happens because of something else.

• Cause and effect relationship between events.

• Helps explain how and why things happen in the world.

• Important in science and philosophy for understanding reality.

• David Hume questioned how we can know causality for certain, saying we only observe events happening together, not a necessary connection.

• Aristotle identified different types of causes (material, formal, efficient, final).

Plato

True knowledge is of eternal Forms (not of the physical world); learning is recollection.

Aristotle

Knowledge begins in the senses but must be structured by reason and logic.

Rorty

Denied objective truth; focused on the usefulness of beliefs rather than their correspondence to reality.

Knowledge is not a perfect copy of reality — it’s about usefulness and language.

Chomsky

Language is innate, suggesting certain structures of knowledge may be hardwired.

We are born with some basic knowledge in our minds that helps us learn language.