Philo 1 inference


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Philo 1 inference

  1. 1. Introductory Notion of JudgmentThe mind does not stop in the formation ofideas and terms.It starts asserting relationship betweenthese concepts, either affirming or denyingit.Examples:“Juan is a Filipino”. Judgment“Juan is not a Filipino”.
  2. 2. What is Judgment in Logic?• A mental act of affirming or denying the relationship between two concepts. A mental operation or act by which the mind affirms or denies anything whatsoever.• Some people are generous Affirmation Man is a creature. Denial A dog is not rational. A tree is not a cow.
  3. 3. Examples of JudgmentEvery man is a rational animal.No dog is human.A tree is not a cow.Baguio City is the summer capital of thePhilippines.Joseph “Erap” Estrada is the president ofthe Philippines.Some people are generous.
  4. 4. Judgment and PropositionTheoretically, judgment is a mental act notyet verbally expressed. It exists only in themind. But ideas need terms as a means ofexpression, so judgments need a tool forcommunication. This tool is calledPROPOSITION. Therefore, everyproposition is a judgment.
  5. 5. Prerequisites of Judgment For a judgment to be valid and truecertain prerequisites must be followed.They are the following:1. The two related concepts must bethoroughly understood.2. There must be an intellectualcomparison between the two concepts/terms. The mind must comprehend theiridentity or non-identity as basis forpronouncing a judgment.
  6. 6. • 3. There must be an objective perception of the relationship of the two concepts whether or not such relationship is of agreement or disagreement.• 4. There must be a mental pronouncement of the agreement or disagreement of the terms compared.
  7. 7. Introductory Notion of Proposition A judgment is mental act not yetverbally expressed. But man has thefaculty of speech and can put this inwriting. So that if ideas need terms forexpression, so judgment need a tool forcommunication. This tool is called proposition.
  8. 8. A proposition is defined as a declarativesentence which expresses a relation ofaffirmation or denial between two terms.It is a verbal expression of judgment.
  9. 9. Types of Proposition There are two types of proposition: the Categorical and the Hypothetical. We shall discuss first the categorical. The Hypothetical will be discussed later.• CATEGORICAL PROPOSITIONS. A categorical is one in which the predicate term is either affirmed or denied of the subject term. If the predicate term is affirmed by the subject term the, the two terms are united and the proposition is called affirmative. If the two terms are denied of each other as indicated by the negative adverbs no or not, the proposition is called negative. The subject and the predicate are united or separated by a copula, the present tense of the verb “to be”, am, is or are.
  10. 10. All pine trees are plants.Some plants are not flowers.All people are beautifulI am a finite being.The farmer is God’s servant.No man is immortal.
  11. 11. Components of Categorical Proposition 1. Subject Term 2. Predicate Term 3. Copula
  12. 12. Truth or Falsity• The mind’s act of affirming or negating a relationship of terms in a proposition is in fact a declaration of truth or falsity. But how do we know a judgment is true or false? It is the conformity between the mental judgment and objective reality. Or the congruence between what is in the mind and the objective world.
  13. 13. A tree is a plant.The sun revolves around the earth.Flowers are petals.A triangle has four sides.Igorots are Filipinos.A dog is an irrational animal.
  14. 14. Reduction To Logical Form• A proposition may run like this: “The dog barks. This has to be reduced to logical form – forming a categorical proposition by changing the verb into a linking verb in order to have a copula. Modify slightly or add a word without changing the thought of the original proposition.
  15. 15. ALL DOGS BARK. In logical form may be asfollows: All dogs are barking animals. All dogs are barkers. All dogs are animals that bark.FILIPINOS WORK HARD. In logical form may be as follows:
  16. 16. Properties of Categorical PropositionQuantity of Proposition1. Universal Proposition2. Particular Proposition3. Singular PropositionQuality of Proposition1. Affirmative Proposition2. Negative Proposition
  18. 18. INFERENCE:THE REASONING PROCESSNature of Reasoning Logic is the science of correct thinking. It startswith ideas and terms and leads to the formation ofjudgment and proposition. Using judgment andproposition it proceeds to the intellectual activity calledreasoning process or inference.
  19. 19. Notion of Inference the process in which from a sequence of propositions, we arrive at a conclusion. The mind proceeds from one proposition to other propositions. Mental process of comparing 2 concepts with a common third term in order to establish agreement or disagreement with each other. Inference consists of 2 parts: the antecedent and the consequent.
  20. 20. ANTECEDENT- CONSEQUENT RELATIONSHIP Antecedent (premises) S E Q U inference E N C E Consequent (conclusion)
  21. 21. Example:Crimes are evil acts. AntecedentBut murder is a crime. Crime appears 2x. Common 3rd term. Sequential relationTherefore, murder is an evil act. Consequent
  22. 22. There are three terms:• Crimes - appears twice in the premises. This term establishes a sequential relation between the 2 premises.• Evil acts• Murder
  23. 23. Kinds of Inference Immediate and Mediate InferenceImmediate Inference A short-cut way of reasoning process passing directly from one proposition, without the aid of a second proposition or a third term, to a new proposition but not a new truth. example: Crimes are evil acts. Therefore, crimes are evil acts.
  24. 24. Kinds of Inference (cont.)Mediate Inference A process of reasoning whereby the mind passes from two propositions which are called premises to a new proposition called conclusion thru the mediation of of a common third term called the middle term. The mind arrives at a new truth. This reasoning process or inference is called a syllogism. The structure of a syllogism consists of 3 declarative sentences: 2 premises and one conclusion. example: Crimes are evil acts. But murder is a crime. Therefore, murder is an evil act.
  25. 25. The Old CowboyYou have lived to be 80 and know who you are...then along Comes someone and blows it all to hell........
  26. 26. An old cowboy sat down at the Starbucks And ordered a cup of coffee. As he sat sipping his coffee, a young woman sat Down next to him. She turned to the cowboy and asked, Are you A real cowboy?
  27. 27. He replied, Well, Ive spent my whole life breaking Colts, working cows, going to rodeos, fixing fences, Pulling calves, bailing hay, doctoring calves, cleaning My barn, fixing flats, working on tractors, and feeding My dogs, so I guess I am a cowboy.
  28. 28. She said, Im a lesbian. I spend my whole day thinking About women. As soon as I get up in the morning, I Think about women. When I shower, I think about Women. When I watch TV, I think about women. I even think about women when I eat. It seems That everything makes me think of women.
  29. 29. The two sat sipping in silence. A little while later, a man sat down on the other side Of the old cowboy and asked, Are you a real cowboy? He replied, Hell, I always thought I was, but I just found Out that Im a lesbian
  31. 31. DEDUCTIVE REASONING - the mind proceeds from a universaltruth to a particular one.Examples:1. Every man is rational But the teacher is a man. Therefore, the teacher is rational.2. A dog is an animal. But a person is not an animal. Therefore, a person is not a dog.
  32. 32. INDUCTIVE REASONING - the mind proceeds to conclude fromindividual or particular cases to theexistence of a universal law or principle.Example: Filipinos have 2 eyes each. Americans have 2 eyes each. Chinese have 2 eyes. But Filipinos, Americans and Chinese are people. Therefore, people have 2 eyes each.
  33. 33. THE CATEGORICAL SYLLOGISM - a verbal expression of an inference. An oralor written discourse showing agreement ordisagreement between 2 terms on the basis of acommon third term. - an argumentation from 2 propositions calledpremises, we arrive at a third proposition calledconclusion. - must always have a sequential relation inthe presence of a middle term.
  34. 34. Observe the ff. propositions. Do theyconstitute a syllogism? Why?Every man is a bipedBut every cow is a quadruped.Therefore, every cow is not a man.All creatures are mortal.But a person is a creature.Therefore, a person is mortal.
  35. 35. COMPONENTS OF A CTEGROICAL SYLLOGISM SyllogismMajor Premise Minor Premise Conclusion Major term (T), Minor term (t), Middle term (M)
  36. 36. Observe the following example:Every flower is a plant. (Major Premise)But a fish is not a plant. (Minor Premise)Therefore, a fish is not a flower. (Conclusion)T – flowert – fishM – plant
  37. 37. The three (3) terms in the premises must beUNIVOCAL.A President is a ruler.But a ruler is 12-inch thing.:. A 12-inch thing is a President.Therefore is represented by :.