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Diagramming arguments
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Diagramming arguments

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Slides from lecture #2 in Phil 57 ("Logic and Critical Reasoning), section 3, at San Jose State University, Fall 2010.

Slides from lecture #2 in Phil 57 ("Logic and Critical Reasoning), section 3, at San Jose State University, Fall 2010.

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  • 1. Homework from last time:
    • 11. Freedom of the press is an important freedom of societies. It is like the right to life with respect to individuals.
    • Argument, or something else (e.g., report, illustration, explanation)?
  • 2. Homework from last time:
    • 12. An agreement cannot bind unless both parties to the agreement know what they are doing and freely choose to do it. This implies that the seller who intends to enter a contract with a customer has a duty to disclose exactly what the customer is buying and what the terms of the sale are.
  • 3. Homework from last time:
    • 13. Neither the butler nor the maid did it. That leaves the chauffer or the cook. But the chauffer was at the airport when the murder took place. The cook is the only one without an alibi for his whereabouts. Moreover, the heiress was poisoned. It’s logical to conclude that the cook did it.
  • 4. Homework from last time:
    • 14. If a piece of information is not “job relevant,” then the employer is not entitled qua employer to know it. Consequently, since sexual practices, political beliefs, and associational activities are not a part of most job descriptions, employers qua employers are not entitled to information about them from a prospective employee. And since they do not directly affect one’s job performance, they are not legitimate information for any employer to know in the determination of hiring a job applicant.
  • 5. Homework from last time:
    • 15. Parents who were abused as children are themselves more often violent with their own children then parents who were not abused. This proves that being abused as a child leads to further abuse of the next generation. Therefore, the only way to stop the cycle of child abuse is to provide treatment for abused children before they themselves become parents and perpetuate this sad and dangerous problem.
  • 6. Diagramming Arguments Phil 57 section 3 San Jose State University Fall 2010
  • 7. Arguments
    • Claim that is supported (conclusion)
    • Claims that offer support/reasons in favor of believing the conclusion (premises)
    • Sometimes it takes some work to identify conclusion and premises!
  • 8. Diagramming arguments
    • Number the claims (1, 2, 3, …)
    • Use “+” to indicate that two or more premises work together to support a conclusion.
    • Use a line ( _______ ) under premises and above the conclusion they support.
  • 9. Diagramming arguments: an example.
    • “There cannot be any emptiness; for what is empty is nothing, and what is nothing cannot be.”
  • 10. First: number the claims.
    • There cannot be any emptiness
    • what is empty is nothing
    • what is nothing cannot be.
    • Useful to break out and number individual claims, even if they’re in the same sentence.
  • 11. Next: work out relations of support.
    • There cannot be any emptiness ( conclusion )
    • what is empty is nothing ( premise )
    • what is nothing cannot be. ( premise )
  • 12. Next: work out relations of support.
    • (2) what is empty is nothing ( premise )
    • (3) what is nothing cannot be. ( premise )
    • _____________________________________
    • There cannot be any emptiness ( conclusion )
    • (2) + (3)
    • (1)
  • 13. Another argument
    • “Lentils are healthy. There are many reasons for this. They reduce heart disease. They are a great source of fiber and protein. And, they are low in fat and simple carbohydrates.”
  • 14. First: number the claims.
    • Lentils are healthy.
    • There are many reasons for this.
    • They reduce heart disease.
    • They are a great source of fiber and protein.
    • They are low in fat and simple carbohydrates.
  • 15. Next: work out relations of support.
    • Lentils are healthy.
    • There are many reasons for this.
    • They reduce heart disease.
    • They are a great source of fiber and protein.
    • They are low in fat and simple carbohydrates.
    • Each premise here provides an independent reason to accept the conclusion.
  • 16. Next: work out relations of support.
    • (2) There are many reasons for this.
    • Lentils are healthy.
    • (2)
    • (1)
  • 17. Next: work out relations of support.
    • (3) They reduce heart disease.
    • Lentils are healthy.
    • (3)
    • (1)
  • 18. Next: work out relations of support.
    • (4) They are a great source of fiber and protein.
    • Lentils are healthy.
    • (4)
    • (1)
  • 19. Next: work out relations of support.
    • (5) They are low in fat and simple carbohydrates.
    • Lentils are healthy.
    • (5)
    • (1)
  • 20. Relations of support for whole argument:
    • (2) (3) (4) (5)
    • (1)
    • No “+” because the premises don’t need to be together to support the conclusion.
    • (Any one of them alone is enough to support the conclusion.)
  • 21. Diagramming arguments: an example.
    • “You should vote for the ballot measure that legalizes and taxes marijuana in California. California’s state budget is hurting, and new tax revenue will help. Plus, the state spends too much incarcerating people for possession of marijuana. If the ballot measure passes, marijuana will be legal and we won’t spend so much money on jails.”
  • 22. First: number the claims.
    • You should vote for the ballot measure that legalizes and taxes marijuana in California.
    • (2) California’s state budget is hurting
    • (3) New tax revenue will help the state budget
    • (4) The state spends too much incarcerating people for possession of marijuana.
    • (5) If the ballot measure passes, marijuana will be legal and we won’t spend so much money on jails.”
  • 23. Next: work out relations of support.
    • You should vote for the ballot measure that legalizes and taxes marijuana in California.
    • (2) California’s state budget is hurting
    • (3) New tax revenue (from taxing marijuana) will help the state budget
    • (4) The state spends too much incarcerating people for possession of marijuana.
    • (5) If the ballot measure passes, marijuana will be legal and we won’t spend so much money on jails.”
  • 24. Next: work out relations of support.
    • (2) California’s state budget is hurting
    • (3) New tax revenue (from taxing marijuana) will help the state budget
    • _____________________________________
    • You should vote for the ballot measure that legalizes and taxes marijuana in California.
    • (2) + (3)
    • (1)
  • 25. Next: work out relations of support.
    • (2) California’s state budget is hurting
    • (4) The state spends too much incarcerating people for possession of marijuana.
    • (5) If the ballot measure passes, marijuana will be legal and we won’t spend so much money on jails.
    • ___________________________________
    • (1) You should vote for the ballot measure that legalizes and taxes marijuana in California.
    • (2) + (4) + (5)
    • (1)
  • 26. Next: work out relations of support.
    • Both pieces of the argument together:
    • (2) + (3) (2) + (4) + (5)
    • (1)
    • Premises 2 and 3 work together to support conclusion.
    • Premises 2, 4, and 5 work together to support conclusion.
  • 27. Homework – diagram the argument
    • 1. Whatever doesn’t kill me makes me stronger. The amount of coffee I drink is a lot, but it hasn’t killed me. So all that coffee makes me stronger.
  • 28. Homework – diagram the argument
    • 1. Whatever doesn’t kill me makes me stronger. The amount of coffee I drink is a lot, but it hasn’t killed me. So all that coffee makes me stronger.
  • 29. Homework – diagram the argument
    • 2. Time is either real or unreal. Space is real. Time cannot be separated from space. If something is real, and another thing cannot be separated from it, then that thing must also be real. So, time is real.
  • 30. Homework – diagram the argument
    • 2. Time is either real or unreal. Space is real. Time cannot be separated from space. If something is real, and another thing cannot be separated from it, then that thing must also be real. So, time is real.
  • 31. Homework – diagram the argument
    • 3. Jewish dietary law defines as “kosher” only meat from particular kinds of animals. Mammals that have cloven hooves and that chew their cud can be kosher, but mammals missing one of these two are not. (So rabbits, which ruminate but don’t have hooves, are not kosher.) Fish must have both fins and scales to be kosher. Milk and meat must not be consumed in the same kosher meal. (Fish don’t count as meat or dairy in this reckoning.) All of this means that the Aigi Kampoi (a fish-tailed goat of folklore) would be kosher because it has cloven hoofs, chews its cud, and has fins and scales. However, it would still be considered a meat meal, even though it’s partially fish. So you can’t eat dairy with it.
  • 32. Homework – diagram the argument
    • 3. Jewish dietary law defines as “kosher” only meat from particular kinds of animals. Mammals that have cloven hooves and that chew their cud can be kosher, but mammals missing one of these two are not. (So rabbits, which ruminate but don’t have hooves, are not kosher.) Fish must have both fins and scales to be kosher. Milk and meat must not be consumed in the same kosher meal. (Fish don’t count as meat or dairy in this reckoning.) All of this means that the Aigi Kampoi (a fish-tailed goat of folklore) would be kosher because it has cloven hoofs, chews its cud, and has fins and scales. However, it would still be considered a meat meal, even though it’s partially fish. So you can’t eat dairy with it.
  • 33. Homework – diagram the argument
    • 4. If morality requires freedom, and punishment requires morality, it follows that punishment requires freedom.
  • 34. Homework – diagram the argument
    • 4. If morality requires freedom, and punishment requires morality, it follows that punishment requires freedom.
  • 35. Homework – diagram the argument
    • 5. God is all-powerful, all-loving, and all-knowing. Since God is all-powerful, he has the capacity to rid the world of evil. Since God is all-knowing, he has the capacity to know where and when evil occurs. Since God is all loving, he wants to get rid of evil in the world. However, there is evil in the world. Thus, God does not exist.
  • 36. Homework – diagram the argument
    • 5. God is all-powerful, all-loving, and all-knowing. Since God is all-powerful, he has the capacity to rid the world of evil. Since God is all-knowing, he has the capacity to know where and when evil occurs. Since God is all loving, he wants to get rid of evil in the world. However, there is evil in the world. Thus, God does not exist.
  • 37. Homework – diagram the argument
    • 6. Some things that exist are caused by other things. Nothing can be the cause of itself. Nor can there be an endless string of objects causing other objects to exist. Therefore, there must be an uncaused first cause: God.
  • 38. Homework – diagram the argument
    • 6. Some things that exist are caused by other things. Nothing can be the cause of itself. Nor can there be an endless string of objects causing other objects to exist. Therefore, there must be an uncaused first cause: God.