4Classdiscussiononly.Teacher.Armandltan.Associateprofessor. Philosophydepartment

1- BASIC CONCEPTS YolaFile#171109 4ClassDiscussionOnly.Teacher.ArmandLTan.AssociateProfessor. PhilosophyDepartment SillimanUniversity. s1. LOGIC. [ Gk. logos:reason]; Copi: study of the methods and principles used to distinguish good (correct) from bad (incorrect arguments. Though logic may be defined in many other ways, central 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/exclamations/suggestions/proposal are not statements. [traditional use: Proposition]

2a. Synthetic/ 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 premise is the 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/ accordingly.

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 all 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) /Hence you are studying b. All lawyers are spies.(false) All liars are spies/ 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) -3-

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 tvalue : true/false : valid or invalid combination :

4a. Sound N Unsound Argument

------Formal Arguments -----: : : : : Valid -- Invalid : Sound : Unsound (at least one false premise)

s5. DEDUCTION/INDUCTION: difference is cantered on the validity of 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 vegetarians 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/ So probably all Christians are Catholic. -4-

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 accumulation 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 repenteth 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 Christian. But Marx was not a Christian. Therefore he was not a communist.

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 no arguments 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 mind. The teacher is not either of the two. We conclude that we really don’t not know.