Parmenides the model Parmenides the model –Anti-experience—not a reason to believe –Leads to false conclusions—error No change (or motion) No change (or motion) –No talk of “is not” b/c doesn’t exist Like saying 無無也Like saying 無無也 –Becoming = ‘is not’ turns into ‘is’ So illegitimateSo illegitimate –Change is a thing’s not-being  its being Predication blended with existencePredication blended with existence

Existence claim supported Existence claim supported –Law of preservation of matter –Consistent with constant change ( 陰陽 yin-yang) –No ‘is’ verb-- 有 無 you-wu exist-notexist and 也 Other Greek Rationalists Other Greek Rationalists –Zeno and motion paradoxes –Pythagoras and concept of “proof” Mathematical mysticismMathematical mysticism –Euclid: How to think—axioms + proof  all truth Role of definitions  Socrates & ethics as theoryRole of definitions  Socrates & ethics as theory Examined life = theory of the healthy soul=ethicsExamined life = theory of the healthy soul=ethics

Socratic Method Socratic Method –Doubt — but much more –Rationally motivated doubt Still in the same structure — how proof motivates doubtStill in the same structure — how proof motivates doubt Logic as disciplined discourse Logic as disciplined discourse –'Argument': proof v quarrel sense –Proof consists of sentences Premises and conclusionPremises and conclusion Conversational implicationConversational implication –Conclusion “ follows from ” the premises –Needs explanation

Valid: has a form such that if the premises were true, the conclusion would also be true Valid: has a form such that if the premises were true, the conclusion would also be true Formal-symbolic representation Formal-symbolic representation –Venn diagram technique –Classic example: all C are B, all B are A, all C are A Aristotle ’ s syllogism — now propositional logicAristotle ’ s syllogism — now propositional logic –Modes Ponens If … then … –Model Tolens &Disjunctive syllogism

Quiz for New Years? Formulate the problem of evil. Explain the advantage of a symbolic statement.

Use the same form Use the same form –With plainly true premises –And a false conclusion –Can not be a valid form Distinguish from argument by analogy Distinguish from argument by analogy –Form of induction on a similarity –How do I know you have minds?

Definition Definition –Valid argument –True premises (all) Conclusion of two definitions Conclusion of two definitions –Sound arguments have true conclusions If an argument is valid and has true premises, then the conclusion is true.If an argument is valid and has true premises, then the conclusion is true. A sound argument is a valid argumentA sound argument is a valid argument A sound argument has true premisesA sound argument has true premises Therefore a sound argument has a true conclusionTherefore a sound argument has a true conclusion What if conclusion of valid form is false What if conclusion of valid form is false –Contradiction of “all” is “one or some” –At least one premise is false

Deductive v inductive Deductive v inductive –Guarantee by form v good reason for Could be wrong—reasonable conclusionCould be wrong—reasonable conclusion Can’t use rule of the triad—conclusion false and still valid and premises trueCan’t use rule of the triad—conclusion false and still valid and premises true –Weakest to strongest Analogy (weak form) one likenessAnalogy (weak form) one likeness Classical induction: next one might changeClassical induction: next one might change Sampling, polling and statistics (with rigor)Sampling, polling and statistics (with rigor) Science (strong form) explain laterScience (strong form) explain later –Inference to the best explanation

Uses the same model: called the practical syllogism Uses the same model: called the practical syllogism –Belief-desire explanation of action in western thought Belief + desire (sentence) entail intention/actionBelief + desire (sentence) entail intention/action May substitute a norm/value/principle for “ desire ”May substitute a norm/value/principle for “ desire ” –Desire the perception of value To get a value (ought) conclusion, you need a value premise To get a value (ought) conclusion, you need a value premise –You can't get an "ought" from an "is" –Abortion argument example

If conclusion false, then either invalid or premise false If conclusion false, then either invalid or premise false Key to scientific induction (v. Classical induction) Key to scientific induction (v. Classical induction) –Laws and experimental setup predict a result Premises are laws + observations/measurementsPremises are laws + observations/measurements Conclusion is a prediction of experimental outcomeConclusion is a prediction of experimental outcome –If prediction is false, one+ premise must be false Usually the setup, but after repeated checking calls one of the laws into questionUsually the setup, but after repeated checking calls one of the laws into question True  confirm (false  disconfirm)True  confirm (false  disconfirm)

Premises and deductive conclusion Premises and deductive conclusion –Laws: pure water freezes at 0 C. –This is water –This is below 0 C. –This will freeze Doesn’t freeze—so? Doesn’t freeze—so? –Thermometer wrong, salt/alcohol mixed in water etc. –If all ruled out—reject the law Laws, measurements, mathematics Laws, measurements, mathematics –Precision of prediction for science

Socratic method no experiment Socratic method no experiment –Use argument to derive a contradiction –Must change a premise. Not necessarily the definition –Limits of Socratic (scientific) method: only exposes error not truth –Trial and error, creativity, insight, genius for premises

God is omnipotent, omniscient and all good creator of everything God is omnipotent, omniscient and all good creator of everything –Hence, there is no evil Formal statement: A  B  C  D. All good Formal statement: A  B  C  D. All good –"All things there are” –"things God made" –"things God wanted" –"good things“ Evil = not good (definition) Evil = not good (definition) –There is no evil (everything is good/God’s will)

What is the alternative to no-evil? What is the alternative to no-evil? –God does not exist? Why does it not prove that? –Theodicity: possible solutions to the problem of evil Limited godLimited god Free will and necessary evilFree will and necessary evil Human and divine “good”Human and divine “good”

Applies metaphysical analysis to ethics, truths are moral facts. Applies metaphysical analysis to ethics, truths are moral facts. –one (conventions many) –unchanging (vs. mores) –knowable (definitions) –rational (Socratic method) and –real. Why care about those peculiar facts? Why care about those peculiar facts? –No man knowingly does evil

No answers — Socrates the skeptic No answers — Socrates the skeptic –Dies ignorant –Famous lament — and student response At least knows he doesn ’ t knowAt least knows he doesn ’ t know 知之為知之不知為不知是知也 知之為知之不知為不知是知也 Deeper problem — many different consistent doctrines Deeper problem — many different consistent doctrines –Contradiction not easy to prove –Plato cheats!

Death by legislature — bill of attainder Death by legislature — bill of attainder –Plato ’ s hatred of democracy Better for policy and choice of leadersBetter for policy and choice of leaders Not for judgment of guiltNot for judgment of guilt Takes Socrates as a figure in dialogues Takes Socrates as a figure in dialogues –Source of our account of Socratic method –Classic example in Thrasymachus dialogue

Parmenides: the real world and ethical ideal blend Parmenides: the real world and ethical ideal blend Focus on search for definitions Focus on search for definitions –Socrates origin or geometry Result is that meaning/value = being Result is that meaning/value = being –Really that being = meaning/value

Conform to rationalist presuppositions Conform to rationalist presuppositions –One -- instances are many –Unchanging -- remain while that kind of thing –Knowable -- beliefs about objects (Heraclitus and Parmenides) –Rational -- Socratic method –Hence real Idealism. Definitions (meanings:ideas) are realIdealism. Definitions (meanings:ideas) are real "Things" are not"Things" are not

Implicit in Plato's dialogues with Socrates Implicit in Plato's dialogues with Socrates No lists. What is common to all instances No lists. What is common to all instances No vagueness. Strong No vagueness. Strong No circularity (or mere synonyms) No circularity (or mere synonyms) –Definition so usable in arguments No hearsay -- test by expert knowledge No hearsay -- test by expert knowledge –Real v. Nominal definitions Test by reason. Socratic method Test by reason. Socratic method

Intellectual forms correspond to definitions (meanings) Intellectual forms correspond to definitions (meanings) Forms provide a unified answer to questions in all fields of philosophy Forms provide a unified answer to questions in all fields of philosophy –Metaphysics: what is real. Real definitions v. Nominal –Epistemology: what is knowable. Like soul/mind-- intellectual –Logic: the thinkable objects (not laws of thought but semantics) –Ethics: no man knowingly does evil. Health of the soul Objects of striving -- teleological account of changeObjects of striving -- teleological account of change