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A Powerpoint on Logic


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A Powerpoint on Logic

  2. 2. When do you say that someone/ something is logical or illogical?
  3. 3. What is Logic, then?
  4. 4.  Logic is the study of methods and principles used to distinguish correct reasoning from incorrect reasoning (Cohen )  Science and art of correct thinking
  5. 5. Goals of Logic A. Identify good arguments B. To be able to make good arguments
  6. 6. Types of Logic (form and content) 1. Formal Logic -about aspect of forms, structures, sequences and the following of the rules e.g. Life is a matter of choice. (what’s the subj.?verb?pred.?...)
  7. 7. 2. Material Logic concerned with subject matter, content and function *Why and how is life a matter of choice?
  8. 8. Types of Logic (Process of thinking) 1. Deductive Logic universal to particular; general to specific
  9. 9. e.g. All III-13 students are pretty. Agatha belongs to III-13 Therefore, Agatha is pretty.
  10. 10. 2. Inductive Logic  particular to universal, specific to general
  11. 11. e.g. The mango falls, the book, the pen… Therefore, bodily objects fall.
  12. 12. 1. Simple Apprehension -process of grasping the objective reality where concept/idea is formed and expensed in terms.
  13. 13. - The act by which the mind grasps or lays hold of an object, without affirming or denying anything about it - (L) Apprehendere: become aware of, recognize or contemplate and object
  14. 14.  When I understand what is meant by “triangle”, “man”, and “stupid”, this understanding is a simple apprehension
  16. 16. 2. Judgment - assertion or denial of something in case after all the available/needed ideas are organized and analyzed. Proposition is used in expressing judgment
  17. 17.  Simple apprehension + affirmation/denial = Judgment
  18. 18. E.g.  The triangle is an isosceles triangle.  This man is stupid.  Every changing being is imperfect.
  19. 19.  Simple apprehension => concept or mental word : judgment=> mental statement* * Representations formed in by the mind
  20. 20. Things to consider in making judgment: 1. All ideas involved are to be understood 2. Each ideas is to be contrasted/compared with the other ideas. 3. Ideas compared are to be judged as to whether in agreement or in agreement. 4. Judgment is expressed as propositions. 5. Judgment is based on inferences.
  21. 21. Logical Truth and Falsity of Judgment  A judgment is true when real relationship of two ideas/realities being compared is established or in agreement  And false if relationship is not established and not in agreement
  22. 22. Convince Me Why!  Is death penalty justified?  Is the Philippines a progressive country?  Should divorce be allowed in the Philippines?
  23. 23. 3. Reasoning  Process with which one advances from premises to conclusion to prove something 1 Inferences 2 Judgment 3 Conclusion
  24. 24. Proposition (Cohen) –assertions that are either true or false and stated in declarative form; written or spoken expression of the mental statement e.g. This is a dog. The animal is not a cat.
  25. 25.  Argument, Premise and Conclusion 1. Argument- group of propositions of which one follows the others to provide support on ground for the truth of that one 2. Premise- a proposition or inference in an argument 3. Conclusion- an affirmed argument
  26. 26. Examples of Premise and Conclusion 1. No one was present when life first appeared on earth. Therefore, any statement about life’s origin should be considered a myth. 2. Since all humans come from a small number of African ancestors, believing in different races is ridiculous. 3. Cigarette selling should stop. After all, cigarette is the leading cause of death.
  27. 27.  Arguments are acts of reasoning  In reasoning, the known truths are related to new truth(premise) to form conclusions(resulting to truth)
  28. 28. Two Principle of Reasoning  Principle of Non-Contradiction an object cannot be true and false at the same time. e.g. The chalk is white and non-white. You are beautiful and ugly.
  29. 29.  Principle of Excluded Middle every predicate can either be truly affirmed or truly denied of every subject