Descartes
What is the method of doubt?
A systematic process where Descartes doubts everything that could possibly be doubted, including senses, body, and external world, to find something indubitable.
What does tabula rasa mean?
It means “blank slate.” Locke argued that the mind is empty at birth and all knowledge comes from experience.
Translate esse est percipi.
“To be is to be perceived.”
What is the difference between impressions and ideas?
Impressions are vivid, immediate experiences (like pain or color). Ideas are faint copies of impressions (like memories or imagination).
What is Moore’s “proof of an external world”?
He holds up one hand and says “Here is one hand,” then another: “Here is another hand.” Therefore, at least two external objects exist.
What is the dream argument?
Descartes notes that dreams often feel just as vivid as waking life, which shows we cannot always trust sensory experience as a source of certainty. There is no distinguishing mark between the asleep and awake, we can never know when we are awake.
Define and name two examples of primary qualities.
Shape, size, motion, and number are examples. They exist in the object itself, regardless of perception.
Why does Berkeley deny material substance?
He argues we never experience matter directly, only ideas in our minds. Therefore, “matter” is an unnecessary fiction.
What is the Copy Principle?
All ideas are copies of prior impressions. Even complex ideas can be broken down into simpler impressions.
How does Moore’s proof refute skepticism?
It shows that ordinary facts we know (like having hands) are more certain than abstract skeptical arguments.
What role does the evil demon play?
The “evil demon” is a thought experiment imagining a powerful deceiver tricking us about everything — used to push doubt to its extreme. God did not need to be all good, just all powerful and all knowing. It was needed to doubt math.
Define and name two examples of secondary qualities.
Color, taste, smell, and sound are examples. These depend on the perceiver’s senses.
What role does God play in his theory?
God perceives all things at all times, ensuring their continued existence even when humans are not perceiving them.
Why can’t we perceive necessary connection?
We only ever see one event followed by another (constant conjunction). The “power” or “necessary connection” is never observed.
Why does he trust common sense over doubt?
Because we have more certainty in ordinary knowledge than in skeptical hypotheses. Common sense is a firmer foundation than radical doubt.
What is the Cogito and why is it important?
“I think, therefore I am” is the first indubitable truth Descartes finds: even if deceived, he must exist as a thinking being. It serves as the foundation of his new system of knowledge.
How do simple ideas combine to form complex ones?
Simple ideas come directly from sensation and reflection; the mind then combines them into complex ideas like beauty, justice, or unicorns.
How would Berkeley explain the existence of a tree when no one is looking?
The tree still exists because God is always perceiving it, even if no human is.
Why do we expect the sun to rise tomorrow?
Because of habit or custom. After repeated experiences, our mind forms expectations — but this is not rational proof.
How does Moore differ from Descartes?
Descartes starts with radical doubt and rebuilds knowledge. Moore starts with certainty of ordinary knowledge and rejects skepticism outright.
What was Descartes’ ultimate goal in doubting everything?
To discover a foundation of knowledge that is absolutely certain, upon which science and philosophy could be rebuilt securely.
How does Locke argue against innate ideas?
He claims no ideas are universally shared (like “God” or “morality”), and children/“idiots” lack them. Therefore, all ideas must come from experience, not birth.
What is his critique of Locke’s primary/secondary distinction?
Berkeley claims both kinds of qualities depend on perception — we cannot know qualities apart from how they appear to us.
What challenge does Hume’s skepticism pose for science?
Science relies on induction (predicting future events based on past patterns). Hume argues induction has no rational justification, undermining claims of certainty.
What is a major criticism of Moore’s approach?
That it oversimplifies — skeptics argue Moore just assumes what he’s trying to prove, rather than truly refuting skepticism.