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Chapter 1-10

PHLA10H3 Chapter Notes - Chapter 1-10: Evolutionism, Decision Theory, Testability

Course Code
William Seager

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Readings p. 1-19
CHAPTER 1: What is philosophy?
Subjective realm: opinion
Objective realm: fact
Ethical subjectivism: is the philosophical these that there are no ethical facts, only ethical
Utilitarianism: that action you should perform in a given situation is the one that will produce
the greatest happiness for the greatest number of individuals.
Metaphysics used to describe what there is (exists).
Philosophical problems: Does god exist + knowledge + brain/mind and ethics.
Philosophical skepticism: not even knowing things that we take to be most obvious.
Dualism: mind separate from brain.
Theory of utilitarianism: Actions performed in given situation should produce the most
happiness to the largest amount of people.
Solipsism: mind is the only thing that exists.
Mystical guru model: Making deep and mysterious pronouncements off the top of your head
that sound very important but that are hard to make sense of when you try to think about the
clearly. What philosophy is NOT.
Review questions:
1. What is the difference between objective and subjective? Objective is fact, subjective is
2. If you want to say what philosophy is, why isn’t it enough to list some examples of
philosophical problems? Giving examples would only give a hint of what philosophy is, to give
the full meaning you would have to give a theory and examples/hypothesis.
3. Which of the ideas presented here about what philosophy is also apply to mathematics?
Which do not? Metaphysics & objective realm; can relate to mathematics because they both
describe facts and cannot be change, the things they describe just ARE. Subjective and
utilitarianism do not relate to mathematics because they are opinions.
CHAPTER 2: Arguments
Arguments in two parts: Premise and Conclusion (expressed by declarative sentence, either
true or false).
2 questions we will want to ask about arguments are: Is it deductively valid? Are all the
premises true?
Reductio ad absurdem argument form: Assume the opposite of what you want to prove and see
if the conclusion is absurd thus proving that the first idea is the correct idea.

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Good Arguments rationally persuasive (good reason to believe in the conclusion), Also have
true premise. Premises must be relevant to conclusion. Do not beg the question (if u had
uncertainty about the premise and the conclusion does not help) [p is y/ p is y].
Sounds Argument: Correct form with true Premise.
Deductively Valid argument: If premise is true, so must be the conclusion.
Deductively Invalid argument: Possibility that the conclusion can be false even with true
Conditionals: If/ Then statements (2 separate statements If p then q)
“P being the antecedent and Q being the consequent”
Conditionals don’t say that the antecedent or the consequent are true.
If P the Q has a contrapositive which if NOT P then NOT Q.
A conditional and its converse are not equivalent (if p then q not equal to if q then p).
Review questions:
1. When is a statement or idea valid? (trick question). Philosophers never say whether a statement
or idea is valid or invalid. It is the argument that determines that validity of statement or idea. The
statements or ideas might not make sense, but if the conclusion backs it up, it is still a valid argument.
2. Define what it means to say that an argument is deductively valid? If premise is true, so must
be the conclusion.
3. Invent an example of a valid argument that has a false premises and a true conclusion. Invent an
example of an invalid argument that has a true premises and a true conclusion.
All vegetables grow on trees.
Some fruit are vegetables.
Therefore, some fruit grow on trees.
All humans have a heart.
All animals have a heart.
Therefore, all cats have a heart.
4. Can a statement be a premise in one argument and a conclusion in another? If you think so, give an
example. No, a statement cannot be a premise in one argument and a conclusion in another.
Smith lives in Ontario.
Everyone who lives in Ontario lives in Canada.
Smith lives in Canada
Smith lives in Canada.
Everyone who lives in Ontario lives in Canada.
Smith lives in Ontario.
5. Which of the following argument forms are valid? Which are invalid? For each of the invalid ones,
construct an example of an argument with that form in which the premises are true and the conclusion

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For the argument forms you think are fallacious. Invent names for these fallacies by using the vocabulary
about conditionals presented in the box on page 14.
a) if P, then Q b) if P then Q c) if P, then Q d) if P, then Q
P Q_ Not-P Not-Q
Q P Not-Q Not-P
a) valid
b) invalid
All reptiles are warm blooded,
All alligators are reptiles,
Therefore, monkeys eat alligators.
c) invalid
The world is round; therefore our o-zone layer is round.
The world is no round; therefore our o-zone layer is not round.
d) valid
P - antecedent
Q - consequent
P therefore Q -
Q therefore P Converse
Not P therefore not Q -
Not Q therefore not P - Contrapositive
6. A sign on a store says “no shoes, no service.” Does this mean that if you wear shoes, then you will be
served? This does not mean that if you wear shoes you will be served. There are also other unwritten
rules in society that people just know and follow that would affect if you get service or not.
7. What does it mean to say that an argument is “circular”, that it begs the question? Construct an
example of an argument of this type different from the one presented in this chapter.
A circular argument is when you believe something because a higher power told you it was true. If you
do not believe in the higher power, you do not believe anything they say.
Ex: My doctor told me I have Basal Cell Carcinoma, therefore I have cancer because my doctor said I did.
8. What does it mean to say that truth is objective, not subjective? Truth is objective because it
is fact, subjective is opinion and truth cannot be an opinion.
Readings: pg. 19-52
CHAPTER 3- Inductive and Abductive arguments
Strong, non deductive inference the premise makes the conclusion plausible/possible but not
Induction: these arguments are strong/weak depending on sample size and representation.
(Inference based on information gathered from a previous sample experiment.
Not equivalent
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