Category Archives: PHL 215-01

MWF 1:30p-2:35p
Fawcett 218

PHL 215-01

Dropped with W.

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PHL 215-01

discussion of 7-2

gambling, horseraces, blah blah blah. Is this Logic or something else??

PHL 215-01

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PHL 215-01

1. If you flip three coins simultaneously, what is the chance of getting at least two heads?

50%
2. W hat is the chance of picking the correct (single) number two times in a row in the standard version of
roulette?
3. Flip three coins. If exactly two of them come up heads, you win $2; otherwise, you lose $1. W hat is the
payoff ratio of this bet?

3/8
4. If the chance of your car crashing in the coming year is .05 and the chance of the hard drive in your
computer crashing in the coming year is .03, what is the chance of both your car and your hard drive
crashing in the coming year?
5. If you roll two dice, what is the chance that each die will come up an even number? (In calculating your
answer, use the formula for the probability of independent events, not the dice table.)

25%
6. Flip two coins. If they both come up heads, you win $3; otherwise, you lose $1. W hat is the payoff ratio of
this bet?
7. In craps, you can make a “proposition bet” that 7 will come up on the next roll of two dice. A $1 bet will
win you $4. What is the payoff ratio of this bet?
8. In craps, you can bet that 2 will come up on the next roll of two dice. A $1 bet will win you $29. What is
the payoff ratio of this bet?

9.  Consider the following game. You and another person each draw one card from a deck; the person who
draws the highest card wins. (The cards, in ascending order of value, are 2, 3, 4, 5, 6, 7, 8, 9, 10, J, Q, K,
A.) If you both draw the same value card, no one wins. Suppose you have drawn a 9, and your opponent is
about to draw. W hat is the chance of your winning the game?

10. Consider the following game. You draw a card from a deck. If you draw a face card (a jack, queen, or
king), you win $3. If you draw some other card, you lose $1. What is the payoff ratio of this bet?

PHL 215-01

EX 4.1

  1. yes, mutually exclusive; heart ≠ spade
  2. hw
  3. 50%
  4. hw
  5. 3/13
  6. hw

EX 4.2

  1. r = p [1 + w/b]  —  r = 1/2 [1 + 1/1]  —  1/2 x 2 = 1 = 100%
  2. hw
  3. r = 1/2 [1+ 2/1]
  4. hw
  5. r = 1/3 [1 + 17/9]
  6. hw
  7. r = .3 [1 + 5/2]
  8. hw

EX. 4.3

PHL 215-01

belief ≠ knowledge

Hume: first attack on induction

  • no good reason to assume FRP
  • the sun will rise tmw: Why?
    • the sun has always risen
    • FRP: Future Resembles Past
      • in the past, FRP
      • FRP

Circular!

New problem of Induction (Nelson Goodman)

  • 1, 3, 5, 7, ___?
    • find pattern
    • project pattern
    • fill in next in pattern sequence
  • “What’s a pattern?”

txt

PHL 215-01

indlog-part2

PHL 215-01

5.5:  Some phoilosophers were born in TX. Irvine is a philosopher. Therefore Irvine was born in TX.

Good logic: deductive (guaranteed conclusion) / inductive (≥50% probability)

3-1 (Bold=true italics=false)

1. Anyone who lives in Dayton lives in Ohio.
Anyone who lives in Ohio lives in the United States.
Therefore, anyone who lives in Dayton lives in the United States.
Check all that apply: premises all true 9      logic good 9       good argument 9
2. No American president has been Jewish.
Clinton was an American president.
Therefore, Clinton wasn’t Jewish.
Check all that apply: premises all true 9      logic good 9       good argument 9
3. George Bush is the Pope.
The Pope lives in the Vatican.
Therefore, George Bush lives in the Vatican.
Check all that apply: premises all true 9 logic good 9 good argument 9
4. All roses are red.
All violets are blue.
Therefore, George Bush loves his wife.
Check all that apply: premises all true 9      logic good 9       good argument 9

2-2

Exercise 2-2. Determine whether the following arguments have good or bad logic. If they have bad logic, say so; if
they have good logic, tell whether it is good deductive logic or good inductive logic.
1.  Most people have two kidneys.
Dr. Irvine is a person.
Therefore, Dr. Irvine has two kidneys.
Check one: bad logic 9           good deductive logic 9 good inductive logic 9
2.  All people live in Fairborn, Ohio.
Dr. Irvine is a person.
Therefore, Dr. Irvine lives in Fairborn, Ohio.
Check one: bad logic 9           good deductive logic 9        good inductive logic 9
3.  Some people have only one kidney.
Dr. Irvine is a person.
Therefore, Dr. Irvine has only one kidney.
Check one: bad logic 9 good deductive logic 9        good inductive logic 9
4.  Somewhere between 80 and 90 percent of the students in this class will get a passing grade.
You are a student in this class.
Therefore, you will get a passing grade in this class.
Check one: bad logic 9           good deductive logic 9        good inductive logic 9

PHL 215-01

Exercise 1-3

1. All human beings have reasoning ability.
not susceptible to conceptual CE

2. If there were fewer than 10 people in this room, then there would have to be fewer than 5 people in this room. CE possible: any number of people from 5-9 could be in the room.
3. If something has reasoning ability, then it will necessarily count as a human being.
conceptual CE possible: platypus(!), dolphin, chimp, gorilla
4. There have never been more than 100 people in this room. CE not possible, factual claim
5. If you believe something, and if what you believe is true, then the thing you believe will necessarily count as
knowledge.
CE possible: “lucky guess” example
6. To count as a dog, an animal has to have four legs. CE possible – 3-legged dog
~~~~~~~~~~~~~
Std. definition of knowledge: true justified beliefs

PHL 215-01

EX. 1-1

  1. A N P
  2. Cannot be true by definition of “Pope.”
  3. P
  4. A N P (correction: a c p)
  5. P
  6. A N P (contingently true only if 6 is a negative number)
  7. Cannot be true.
  8. A N P
  9. P
  10. P (but unlikely)

EX. 1-2

  1. CE: Pope
  2. No CE: existential claim, extraordinary claims require extraordinary evidence
  3. No CE: statistical generalization
  4. CE: WA state
  5. CE: Rubies
  6. No CE: statistical generalization
  7. No CE: categorical
  8. CE: universal generalization, this class (also WSU course catalog)
  9. No CE: Statistical generalization
  10. CE: universal generalization — Pope Ratzinger drinks wine at every Mass (regardless of what they claim the wine turns into once a priest says the magic spell)