Valid argument: impossible for premises to be true and conclusion to be false; determined by
Sound argument: all premises are true and conclusion is true.
All tigers are mammals. = A are B.
No mammals are creatures with scales. = No B are C.
Therefore, no tigers are creatures with scales. = No A are C.
1. Rational- Rulers (desire: truth)
On the top of other parts of soul.
2. Spiritual- Guardians (desire: honour & glory/emotions)
Social (about what others think)
3. Appetitive- Producers (desire: pleasure)
Anti-social (just about oneself).
Moderation: all parts of soul agree
Just: rational part dominates.
Sense-perception vs. Thinking
Subconscious action Conscious action (voluntary)
Instinct Knowledge (taking in info/logical)
Cannot be overloaded Can be overloaded
Sight > Seeing > Object
Thought > Thinking > Object How is soul the cause of action?
Types of soul defines the type of action.
The three causes: 1) Origin & Movement (soul made what is there), 2) End (soul made a
purpose/goal), 3) Essence of living body (soul shapes form/physical traits).
Argued that we are forced to believe in stuff habitually, so he has to prove it without keep
thinking it’s true; the beliefs we have may habitually come back to us to make us continue to
believe even in the things that are false. Example: Being told 1+1=3 and just accepting it without
proving it myself.
Tries to show skepticism is false, possibility of universal illusion, dream reality (have to wake up
in order to realize it was a dream), and that we have to believe all facts that are of the same kind
as false if one of them is proven to be false.
How do we believe in truth?
1. Correspondence with reality
2. Result of a process (scientific method)
4. Individual truth (only for who is considered reasonable)
Relations of ideas (certainly true) vs. Matters of fact/experience (possibly true)
Necessary (has to be true in all possible Contingent (doesn’t have to be true in all
worlds) possible worlds)
ex: triangle has 3 sides (always) ex: it’s cold out (not cold during summer)
Analytic (known by definition of words; Synthetic (meaningful truths; “new truth”)
“boring truth”; “definitional truth”)
ex: all bachelors are lonely
ex: all bachelors are unmarried men
Priori (true before experience and don’t need Posteriori (after experience and do need evidence from the world; “no need of evidence from the world; “need checking”)
Left side doesn’t tell very much whereas Right side is meaningful.
Hume claims that philosophy should be done by the right side for it to be meaningful.
Sufficient vs. Necessary
A -> B B -> A
D -> B B -> D
this is sufficient because to get a B, you need this is necessary because you need a B to
either A or D. have A or D.
Perception: anything one is aware of; either impressions or ideas.
• Impression: feeling and thinking presently
• Idea: feeling and thinking non-presently.
Hume argued Necessary + Priori = Analytic and Contingent + Posteriori = Synthetic.
Kant argues that Necessary + Priori = Synthetic too!
(Synthetic because it is meaningful and priori because it is necessary).
He defines metaphysics as being synthetic with “priori” truths.
Example of synthetic with priori truth is math and geometry (Hume thought it was analytic).
The car = a car (analytic)
The car = red (synthetic)
12359 + 64218 = 76521 (synthetic)
You don’t instinctively know it’s wrong because it might take you a second; thus, math is