1. R EVIEW L OGIC & R EASONING Deductive Validity—formal A form such that true premises always  true conclusions A form such that true premises always  true conclusions Informal test—imagine an argument in that form Core vocabulary: if..then.., and, or, not, all, some, none True premises & false conclusion Sound = df valid and all true premises “Conclusions of sound deductive arguments are true” “Conclusions of sound deductive arguments are true” Sound deduction from definition premises

2. O THER L OGICS Inductive—valid when good reasons for the conclusion Not a guarantee Not a guarantee Analogy, induction on example(s), sampling, science Analogy, induction on example(s), sampling, science Inference to the best explanation Practical syllogism: belief-desire to intention Needs an “ought” in premises Needs an “ought” in premises

3. I NCONSISTENT T RIAD ( DEDUCTIVE ) If conclusion false then Either premise(s) false or invalid Either premise(s) false or invalid Formal test for validity Then key to Socratic rational doubt Then key to Socratic rational doubt Doubt one of your premises Doubt one of your premises Also key to science: hypothetical decuction Take current theory as hypotheses Take current theory as hypotheses Measurements, mathematics Predict experimental outcome Predict experimental outcome Outcome falsifies  some hypothesis wrong

4. S OCRATES AND R ELIGION A PPLICATION Socrates no experimental method Needs explicit contradiction—harder Plato cheats a lot Limits: reveals error not truth No method to discover truth Problem of Evil even looser Needs formal statement unlike the usual Believer has many options Accept evil Best of all possible worlds: Free will Limited God Not creator

5. T HEODICY What is the alternative to no-evil? God does not exist? God does not exist? Why does it not prove that? Theodicy: possible solutions to the problem of evil Theodicy: possible solutions to the problem of evil Limited god (not perfect/omnipotent) Free will and necessary evil Necessary for greater good Human and divine “good” Or accept the conclusion Evil is an illusion

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7. B ACK TO S OCRATES : V IRTUE Use metaphysics model on ethics Fundamental reality of ‘virtue’, ‘justice’ Fundamental reality of ‘virtue’, ‘justice’ Search for definitions using Socratic method one (conventions many) one (conventions many) unchanging (vs. mores) unchanging (vs. mores) knowable (definitions) knowable (definitions) rational (Socratic method) and rational (Socratic method) and Real (!) Real (!) Why care about those peculiar facts? No man knowingly does evil No man knowingly does evil

8. W EAKNESS OF S OCRATIC M ETHOD No answers—Socrates the skeptic Dies ignorant Dies ignorant Famous lament—and student response Famous lament—and student response At least knows he doesn’t know 知之為知之不知為不知是知也 Deeper problem Many different consistent doctrines Many different consistent doctrines Contradiction not easy to prove Plato the playwright takes control

9. S OCRATES AND P LATO S TORY Death by legislature—wrong Plato’s hatred of democracy Plato’s hatred of democracy Better for policy and choice of leaders Not for judgment of guilt separate judiciary rule of law Socrates as figure in his dialogues Development of Socratic method Development of Socratic method Classic example in Thrasymachus dialogue Classic example in Thrasymachus dialogue

10. P LATO ' S S YNTHESIS : Parmenides: the real world and ethical ideal blend Real Real is rational; rational is real Focus on search for definitions Socrates Socrates origin and geometry The The idea or concept of a thing Result is the meaning/value = being Really Really that being = meaning Meaning linked to value, purpose The The concept is the thing’s “reality”

11. A RE D EFINITIONS I MPORTANT ? Not to knowing how to speak Vicious circle Vicious circle Real life and children learning Real life and children learning Examples: true, cute, way, water Examples: true, cute, way, water Why such emphasis? Importance to logical method Importance to logical method Socratic method and validity Problem of evil example Problem of evil example Can’t test validity w/o form

12. D EFINITIONS : C ONCEPT R EALITY Conform to rationalist presuppositions One – concrete instances are many One – concrete instances are many Unchanging – remain; things change Unchanging – remain; things change Knowable -- beliefs about objects Knowable -- beliefs about objects Heraclitus and Parmenides Rational -- Socratic method Rational -- Socratic method Hence real Hence realIdealism Definitions (meanings:ideas) real Sensible “things" are not

13. R ULES FOR D EFINITIONS Implicit in Plato's Socrates No lists. What is common to all instances No vagueness. ‘Strong’? No circularity (or mere synonyms) Definition so usable in arguments Definition so usable in arguments No hearsay -- test by expert knowledge Real v. Nominal definitions Real v. Nominal definitions Test by reason. Socratic method

14. C ONCLUSION : T HE F ORMS Forms correspond to definitions (meanings) Meaning “objects” Meaning “objects” Provide unified answer to philo questions Metaphysics: what is real—objective meaning Metaphysics: what is real—objective meaning Real definitions v. Nominal Epistemology: what is knowable Epistemology: what is knowable Like soul/mind--intellectual Logic: the thinkable objects Logic: the thinkable objects Not laws of thought but semantics Ethics: no man knowingly does evil Ethics: no man knowingly does evil Health of the soul Definitions of virtues Objects of striving -- teleological account of change

15. D IFFICULTY : F AMOUS A NALOGIES Cave: sensible appearance v reality C.f. taking hallucinatory drugs C.f. taking hallucinatory drugs Meditation or rational insight Meditation or rational insight Analogy: shadow/object as object/form Equal difficulty in getting you to accept them Equal difficulty in getting you to accept them When you "see" them, you will need no more convincing When you "see" them, you will need no more convincing The character of the object determines your knowledge

16. L INE A NALOGY : Links metaphysics and epistemology Knowability depends on nature of object (Parmenides) Rival view: true belief plus an account (the modern analysis) X knows that P =df. X knows that P =df. P is true X believes that P X has justification for believing that P

18. T HE S UN A NALOGY Rule for identification of forms Logic: there must be a form of forms Logic: there must be a form of forms It must be “more real” than the forms It must be “more real” than the forms The form of the good: of all value Form of the truth/beauty/good

19. M YSTICAL R ESULT Absolute one/being No reason leading to see it It would blind us But necessarily there (or nothing exists)

20. K EY P OLITICAL D OCTRINES The Republic a political plan Justice of political structure like that of individual Justice of political structure like that of individual Same in everything Rule of the correct ruler— intellect

21. T HE P HILOSOPHER K ING Anti-democratic and manipulative Education and classes Social ranks: intellectual, spirited, body-like

22. E ND OF P LATO AND G REEK R ATIONALISM Ancient Chinese idealism next!