Greek: Episteme = knowledge
Greek: logos = thought
Humans have beliefs: "I believe that Santa wears green" and "I believe that Montreal is
east of Toronto".
Question: Do I know these two things?
Humans have true beliefs: I believe that Montreal is east of Toronto, and it's true that
Montreal is east of Toronto
Question: Do I know that Montreal is east of Toronto
No. We could've gotten it right by luck. If I spin until dizzy and say "Montreal is that
way", and this is true, do I have knowledge?
Knowledge involves: (1) a belief that (2) is true and that (3) is justified/proven
Ex: belief: Montreal is east of Toronto
True: It is true that Montreal is East of Toronto
Justification: I have knowledge of maps, and compasses and Canadian geography, and
three truck drivers have told me it's true
Question: Do I know that Montreal is east of Toronto?
Yes and No.
We can have a justified, true belief, but still be uncertain of our belief and/or lack
experiential knowledge of our belief
Ex: First kiss, jury testimony Two types of knowledge:
Knowledge by acquaintance: a justified, true belief that is justified based on first-hand
Ex: I know that kissing is good because I believe it, it is true, it is justified by my own
experience of kissing
Problem: can't we have knowledge of things we have never experienced?
Ex: Columbus sailed the ocean in 1492. Hitler existed.
Knowledge by description: a justified, true belief that is not necessarily justified based on
Ex: I know that Montreal is east of Toronto because three truckers have told me, and I
have seen Canadian maps
Question: How is a true belief justified?
Rationalism: reason justifies true belief
Empiricism: experience justifies true belief
Descartes' Methodological Skepticism
We are often skeptical of things (magic, tall tales, something amazing)
But Descartes suggest we should be skeptical (i.e., doubt the truth of) everything
His purpose: doubt everything until something presents itself as undeniably true, and that
thing is so self-evident that know it as true
Once we know something as certainly true, we can built our knowledge based upon this
sturdy foundation Doubts about sense experience
"I find two completely diverse ideas of the sun in my mind; the one drives its origin from
the sense; according to this idea the sun seems to be extremely small; but the other is
derived from astronomical reasoning… in accordance with it the sun appears to be
several times greater than the earth"
Descartes, Meditation 3
The Dream Argument
"I remind myself that on many occasions I have in sleep been deceived… I see so
manifestly that there are no certain indications by which we may clearly distinguish
wakefulness from sleep."
Descartes, Meditation 1.5
Doubts about mathematics
"How do I know that I am not also deceived each time I add together two and three"
Descartes, Meditation 1.9
Doubts about the existence of God
"is there not a God, or some being, by whatever name I may designate him, i who causes
these thoughts to arise in my mind? But why supposed such a being, for it may be I
myself am capable of producing them?"
Doubts about memory
"I believe that none of those objects which my fallacious memory represents ever
existed" - Descartes, Meditation 2.2
The Evil Daemon (The Evil Genius) "But there is I know not what being, who is possessed at once of the highest power and
the deepest cunning, who is constantly employing all his ingenuity in deceiving me." -
Descartes, Meditation 2.3
Descartes searches for a strong foundation of indubitable knowledge, but everything is
subject to doubt. Is there any foundation for knowledge?
"Doubtless, then, I exist, since I am deceived; and, let him deceive me as he may, he can
never bring it about that I am nothi