4. Katherine KlingseisDr. Charles Rice

5. Logic helps you to think in an orderly way. Like all objects in our world, thought has a form and structure. Thought also follows certain rules and laws which can be learned.

6. Logic has the power to prove a point and to persuade people. Logic is the science of argumentation. Logic can also be used to lead people to wicked conclusions. Knowing logic helps to defend you from manipulation by others. A Face You Can Trust

7. Logic will help to show you the structure of books, so you can read more effectively. Logical thinking leads to clear, understandable writing.

8. All religions and faiths must be logical to be believable. Faith goes beyond logic, but cannot go against it. Logic assists faith in three ways: 1. Logic clarifies and defines beliefs. 2. Logic shows what other beliefs and actions necessarily follow from faith. 3. Logic shows why particular beliefs are reasonable, thus giving further reasons for people to believe; that is, logic strengthens faith.

9. Logic teaches us which ideas contradict each other. Avoiding contradictions makes our thought clearer and our lives more peaceful. The principles of logic are unchanging and always true. Logic can help clarify situations that are confusing by providing us with a reliable “rule” for measuring what we do know.

10. The most important use of logic is for helping us to find the truth. Logic helps us find truth by: 1. Teaching us to define what we are talking about 2. Teaching us to give good reasons for what we are talking about Truth is valuable to us because it: 1. Helps us to change the world 2. Helps us to change ourselves 3. Helps us to know for the sake of knowledge—our natural curiosity.

12. 1. Terms – the words used 2. Premises – the reasons given 3. The Conclusion – the argument made

13. 1. The terms must be clear – all the words must make sense and be used correctly 2. All the premises must be true – each reason given must be correct 3. The argument must be valid – the conclusion must make sense

14. 1. “What do you mean?” All the terms should be clear and unambiguous 2. “What is the point?” All the premises should be true 3. “How do you prove it?” The argument should be logically valid

16. Meaning what you say.

17. Only human beings can ask this question Animals cannot use abstract terms Computers can only manipulate words and numbers in relation to each other

18. Quantity/Extension How many things or individuals are included in the term? How many different types of things are included in the term? What does the term mean? What other words can describe the term? Quality/Comprehension

19. Animal Mammal Primate Human Beings

20. 1. How clear is the term? 2. How many meanings does the term have? 3. Is the term literal or metaphorical? 4. Does the term refer to a group or a particular thing?

21. a. Make sure the terms do not overlap Bad division: Dividing “music” into “rock,” “rap,” “pop,” “alternative,” “country,” and “jazz.” Good division: Dividing music into “Baroque,” “Classical,” “Romantic,” and “Modern.” Bad division: Dividing “teenagers” into “jocks” “preps,” “goths,” “geeks,” and “nerds.” Good division: Dividing “teenagers” into “junior high-age,” “high school- age,” and “graduate-age.” b. Use the same standard of division

22. All definitions should be: 1. Neither too broad nor too narrow 2. Clear, literal, and brief 3. Not negative or circular Bad: “Big blue wobbly thing that mermaids live in: sea.” “Dog: not a cat.” Good: “Medium-sized insectivore with protruding nasal implement: aardvark.”

23. Mistakes regarding terms

24. 1. Changing the meaning of a word during an argument. Who's on Stage? 2. Using the wrong word order. “Would you rather a cannibal ate you or a shark?” 3. Stressing or accenting words. “We don’t have to tell the whole truth, you know.” 4. Exaggerations or understatements “You need to clean your room.” “Oh, so you want me to be your slave!” 5. Misrepresenting your opponent’s position “You think we should all be brainless idiots!”

25. 1. Attacking the person who is making the argument “What do you know? You’re only a kid.” 2. Citing an irrelevant authority “According to 75% of all convicted felons, the American justice system is unjust.” 3. Threatening or shaming the person 4. Appealing for pity or acceptance 5. Relying on ignorance “He can’t prove he earned that money, so he must have stolen it!”

26. 1. Applying a general rule to a special case. “Water is good for you, so take a drink from Lake Erie.” 2. Taking a special case and generalizing it. “I was stung by a bee at camp, so I don’t go camping anymore.” 3. Claiming that what is true of a part is true of the whole. “Every actor in this movie is great, so it must be a great movie.” 4. Claiming that what is true of the whole is true of a part. “She goes to Willard High School, so she must be awesome.” 5. Seeing in black and white. “You have to be either a Republican or a Democrat.” 6. Stereotyping. “I can’t stand all these teenagers with their loud music!”

27. Grace BrideFr. John’s OpponentsOpponents

30. 1. Conclusions that do not follow. “It’s raining today, and I’m sad today, so the rain must make me sad.” 2. Assuming the conclusion before it is proven. “The accused will be given a fair trial before we execute him.” 3. Expecting a simple answer to a complex question. “Are you dumber today than you were yesterday?” 4. Arguing in a circle. “How do I know there’s a God?” “The Bible says so.” “How can I trust the Bible.” “Because God says it’s true.” 5. Contradicting yourself. “I will not tolerate intolerance!”

31. 1. Making a Hasty Generalization. “The Browns keep losing this season. They’ll always be losers.” 2. Assuming that what comes before is the cause of what comes after. 3. Jumping to conclusions based on what a person does not say. 4. Selecting only the evidence that supports an argument. 5. Slanting the question. “Shouldn’t a woman be free to choose?” “Isn’t all human life sacred?”

32. 1. Claiming to refute an argument by refuting its conclusion. 2. Claiming that refuting an argument refutes its conclusion. 3. Ignoring an argument or answering a different argument. 4. Giving an explanation instead of proof. 5. Being cruel to our opponents in debate.

33. Giving good reasons.

34. We write a proposition as a declarative sentence. Ex.: All the students at Calvert High School are human. We must identify in every proposition a subject and a predicate. Subject – what we are talking about Predicate – what we say about the subject Propositions are either true or false. Finding the truth is the main goal of logic, so finding true propositions is essential for finding truth.

35. “One of the best remedies for bad reading and writing is good logic, especially the analysis of propositions. For thinking clearly, expressing your thoughts clearly (in writing or speaking), and interpreting another’s expressions (written or spoken) clearly are three arts that are very closely allied; no one of them can be done well without doing the other two. And the part of logic that is most directly related to this is the part that studies propositions.”

36. To make an argument easier to understand, you can re-phrase each premise into one of the four classic forms: 1. Universal affirmative “All men are mortal.” 2. Universal negative “No men are mortal.” 3. Particular affirmative “Some men are mortal.” 4. Particular negative “Some men are not mortal.”

37. Quality AffirmativeNegative Quantity Universal All ___ are ___.All ___ are not ___. Particular Some ___ are ___.Some ___ are not ___.

38. Proving your point.

40. 1. We can gain knowledge beyond our experience based on what we do know. All objects with great mass emit a gravitational pull, certain dark areas of the universal emit a gravitational pull, therefore these dark areas (black holes) must have mass. 2. We can know universal truths. “All human babies come from human mothers.” 3. We can know necessary and unchangeable truths. The sum of all interior angles in a triangle is 180 degrees.

41. Rule 1: Whatever is universally true of a subject must be true of everything contained in that subject. For example: All men are mortal, I am a man, therefore I am mortal. Rule 2: Whatever is universally false of a subject must be false of everything contained in that subject. Rule 3: Two things identical with the same thing are identical with each other.

42. Rule 4: If one thing is identical with something that a second thing is not identical with, then the first and second things are not identical with each other. For example: No men are angels, I am a man, therefore I am not an angel. Rule 5: A thing cannot be the opposite of itself. Rule 6: A thing either has a certain attribute or it does not have it. In other words, a premise is either true or false.

43. The premises are the evidence, reasons, or proof for an argument. The conclusion is what the argument is trying to prove.

44. Before the premises: Because Since For As If Follows from For the reason that Therefore Hence It follows that Consequently Which shows that So Then Before the conclusion:

45. An explanation simply gives the cause of something. An explanation does not try to prove anything, but only states what is the case.

46. A good argument is one whose terms are all clear, whose propositions are all true, and whose logic is valid. A valid argument gives us certainty about its conclusions. The certainty of the conclusion depends upon the premises. So we know that a conclusion is true when the premises are all true and the logic is valid.