1/BASIC CONCEPTS YolaFile-080618FoClassDiscussionOnly/Teacher/ArmandoLTan/AssociatProfessor/PhilosophyDepartment/SillimanUniversity

s1. LOGIC. [ Gk. logos:reason]; Copi: study of the methods and principles used to distinguish good (correct) from bad (incorrectarguments. Though logic may be defined in many other ways, cen-tral to any definition of logic is the study of argument.

s2. STATEMENT: any sentence that asserts/denies something and is either  true or false¬ but not both.  Commands/questions/exclama-tions/suggestions/proposal are not statements. [traditional use: Proposition] 2a. Synthetic and Analytic Statement.

synthetic: factual and verifiable.

The Christians believed in the doctrine of incarnation.The Hindus believed in the doctrine of metempsychosis. Heraclitus: the eyes are more exact witnesses than the ears.

analytic :  reason/definition/principles of thought

Á square is a four equally sided plane figure. If x is 2 and y is 3, then x+y=5. 2 plus is equal to 4.

In ordinary language¬ the logical truth of any given statement is understood on the basis of the meaning of words.  Example of statements which are by definition logically true/false:

All spinster are unmarried women. Every husband is a female person.

Summary: statement is, gen.speaking, either synthetic/analytic. Synthetic if is either true/false; analytic: either logically true or false.

s3. ARGUMENT: a set/sequence of statements. Two parts: the premisethe statement  that  asserts about  something;  conclusion:  the statement that is claimed to follow from the premise. Ex. "it is good  to eat/drink/and be merry, for tomorrow we shall die."  The first statement is the conclusion, the second, "tomorrow we shall die," is the premise since it provides d reason/ground for eating, drinking/merry making.

Other examples: a. All men are mortal. Socrates is a man. So Socrates is mortal.b. Eternal life belongs to those who live in the present for the

reason that eternity means timelessness and the present has no temporal dimension. Common premise-indicators: assuming that/granting that/ for the reason that/given that/since/whereas/because/for/inasmuch as. Common conclusion-indicators: therefore/hence/thus/so/ we infer/ we conclude/for this reason/it follows that/consequently/accord-ingly. The presence of indicators does not necessarily guarantee/imply an argument: "glasses are breakable. So handle them with care."

Single conditional statement makes no claim, and hence not an argument. "If  we take eternity to mean not infinite  temporal  duration but timelessness, then eternal life belongs to those who live  in the present."

Here none of the assumed categorical statements is asserted as  a premise and conclusion respectively. Hence there is no argument.

3a.  The Form of the Argument. To say that the conclusion must formally or logically follow from the stated premises is to  say that  the  premises and conclusion of any argument need  not  be factually true  so that if an argument is valid because  of  its form¬ all argument having that same form are equally valid.

Logical analogy to the Socrates argument: All boxers are persons of good will. J. Venn is a boxer. /J. Venn is a person of good will.

s4. TRUTH AND VALIDITY: statements are either true/false. arguments are either valid/invalid. Validity is determined by form and not by the truth value of statements.  So we can have a valid argument with entirely false premises and conclusion:

All great philosophers are women.All good teachers are great philosophers.So ally good teachers are women.

On the other hand¬ we can have an invalid argument with entirely true premises and conclusion:

Some professors are critics of society.Some writers are critics of society.Hence some writers are professors.

Logical analogy:

Some men love to watch TV shows. Some women love to watch TV shows. Hence some women are men

Most  important point to remember in this case: no argument  with true premises and a logically false conclusion can be valid.

Some samples of valid/invalid arguments with the combination of truth values:

a. If you are studying, then you are not asleep.(true) You are not asleep.(true) Thus you are studying.(true)

b. All liars are spies.(false) All lawyers are spies.(false) So some lawyers are liars.(true)

c. Either Russell is a logician or mathematician.(true) Russell is not a logician.(false) Thus Russell is a mathematician.(true)

d. If Ramos won, then Cardinal Sin voted for him.(true) Cardinal Sin did not vote for Ramos.(false) Hence Ramos did not win.(false)

e. All feminists are teachers.(false) No teachers are psychologists.(false) Hence no psychologists are feminists.(false)

a and b are invalid; c, d, and e are valid.

Summary: Premises : Conclusion : Argument ---------------------------------------------- All true : true : valid or invalid All true : false : invalid All false : true : valid or invalid All false : false : valid or invalid any truth : true/false : valid or invalid value : combination :

4a. Sound N Unsound Argument

:----- Formal Arguments -----: : : Valiä Invalid : : : : :---------: -------- : : unsound sounä unsound (at least one false premise)

s5.  DEDUCTION/INDUCTION: difference is cantered on the validityof their conclusion.

All vegetarians are religious persons. Polmin Walkaway is a vegetarian. So Polmin Walkaway is a religious person.

Most vegetarians are religious persons. Polmin Walkaway is a vegetarian. So Polmin Walkaway is a religious person.

Difference:  first speaks of all vegetarians and therefore the conclusion necessarily follows; second speaks only of most vege tarians likely to include Mr. Walkaway, and so the conclusion probably but  not necessarily follows. This is so because the evidence in favor of Mr. Walkaway is not conclusive.  In other words,  the probability that Mr. Walkaway is a  religious  person does not, of logical necessity, dismiss the possibility that  he is not.  In term of logical wisdom, it means that even if the premises are true, the conclusion could be false.

Common distinction : deduction proceeds from general  statements to a particular conclusion; induction proceeds  from  particular statement to a general conclusion.

Not always true: 1. deductive argument with particular premises and conclusion; 2. inductive arguments with universal premises and conclusion;  3. inductive argument with particular premises and conclusion.

1. Either Wang stole or legally earned the gold. Wang did not steal the gold. Therefore Wang legally earned it. 2. All saints are Christians and are Catholic. All Popes are Christians and are Catholic. All crusaders are Christians and are Catholic.

Therefore probably all Christians are Catholic.

3. Rachmaninov is a composer and a romantic musician. Verdi is a composer and a romantic musician. Mozart is a composer. Hence Mozart is probably a romantic musician.

s1/s5 EXERCISES

I. Identify the premises and conclusion for passages that contain an argument.

1. Shaw: Any idea that has never been tried is false. Christianity is false simply because it has never been tried.

2.  Aquinas: To every existing thing God wills some good.  Hence, since to love anything is nothing else than to will good to  that thing, it is manifest that God loves everything that exists.

3.  Locke:  Labor is the basis of all property. From this it follows that a man owns what he makes by his own hands  and  the man who does not labor has no rightful property.

4. Aeschylus: So Agamemnon, rather than retreat, endured to offer up his daughter's life to help a war fought for a faithless  wife and pay the ransom for a storm-bound fleet.

5. Leibniz: And there must be simple substances, since there are composites;  for the composite is nothing else than an  accumula-tion or aggregate of the simples.

6. Govier: There can be no such thing as the beginning of time, because all beginnings are in time, and there would be no time in which the beginning of time could be located.

7. Aquinas: Whoever repents of what he has done has a changeable will. God then has a changeable will, since he said, "it repent-eth me that I have made man" [Gen. 6:7]

II. Distinguish between deductive and inductive arguments.

1. If Marx had been a communist, then he would have been a Christ-ian.  But  Marx was not a Christian. Therefore he was not acommunist.

2. We experience that human life is not eternal. Hence all humans are mortal.

3. Martino Salbahe must be a moron because all those morons  whom we have had occasioned to talk to come from his clan.

4. If nothing can happen without a cause is true, then the world has a  cause.  The world has no cause. Therefore nothing can happen without a cause is false.

5.  Arguments with false conclusion are invalid¬ inasmuch as noarguments with false conclusion are valid.

6.  Philosophers  draw conclusions from premises  assumed  to  be true. Americans, Chinese, Filipinos and others  also  do. So probably they are all philosophers.

7. Either the teacher is absent-minded or he is out of his mindThe teacher is not either of the two. We conclude that we really don not know.

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