Philosophy 25Critical ThinkingChapter 1Agenda1) What.docx

Philosophy 25
Critical Thinking
Chapter 1
Agenda
1) What is Philosophy?
2) What is Critical Thinking?
3) Argument Overview
4) Statements & Truth
HW: P. 23 (Exercise 1.2)
Intro to Critical Thinking
What is Philosophy?
“Love of Wisdom”? (Etymology not helpful)
“Philosophy is thinking really hard about the most important
questions and trying to bring analytic clarity both to the
questions and the answers.” Marilyn Adams
“Philosophy is 99 percent about critical reflection on anything
you care to be interested in.” Richard Bradley
3
What is Philosophy?
Another way to approach defining Philosophy is to think about
the questions it asks. Here are three core questions:
Metaphysics: What exists?

Epistemology: What can we know? How can we know what
exists?
Ethics: What is right?
4
What is Critical Thinking?
Philosophers use the skill of critical thinking to answer
philosophical questions.
Critical Thinking is a set of tools for determining whether we
have good reason to believe or accept something.
Connection to Logic: Logic is the study of good reasoning (and
it is another branch of Philosophy)
5
Parts of an Argument
Arguments
Premises Conclusion
Statement/Claim Statement/Claim
6
Statements / Claims
Consider the following sentences:
“Grass is Green.”

“Is Grass Green?”
“Yay!!!”
7
Statements / Claims
Consider the following sentences:
“Grass is Green.”
“Is Grass Green?”
“Yay!!!”
8
Statements / Claims
Statements/Claims are sentences that are either true or false.
But what is truth/falsity?
9
Four theories of truth
Correspondence Theory: A statement is true if it corresponds
with reality
Coherence Theory: A statement is true if it coheres with our
other beliefs
Pragmatic Theory: A statement is true if it is useful for the lives
of human beings
Minimalism: A sentence ‘S’ is true if S
Truth is not a substantial property.

10
Correspondence
Correspondence Theory: A statement is true if it corresponds
with reality
E.g. The statement “Grass is green” is true because (out there in
reality) grass is green.
Pros: it is intuitive –many people find this view of truth
commonsensical. It is objective- truth is not an invention of
people’s minds.
Cons: 1) It is TOO objective – How can we what reality is like
apart from our perceptions? 2) Why should we care about such
an objective notion
11
Coherence
CoherenceTheory: A statement is true if it coheres with our
other beliefs
E.g. The statement “Grass is green” is true because it does not
conflict with other beliefs we hold.
Pros: 1) There is a subjective element to it and it is clear why
truth would matter to human beings.
Cons: 1) The ramblings on an insane person can be completely
coherent, yet we don’t think they are true. This reveals that
there needs to be more to truth than coherence.
12
Pragmatic

Pragmatic Theory: A statement is true if it is useful for the lives
of human beings
E.g. The statement “Grass is green” is true because it helps
human beings to live well. It is sometimes useful to believe that
grass is green. (“If you bring me something green, I’ll give you
$1,000,000”)
Pros: 1) There is both a objective and a subjective element to it.
It seems to blend some pros from both Correspondence and
Coherence Theories.
Cons: 1) Being useful doesn’t seem to guarantee truth.
Believing that I will recover from a disease may be useful, but
doesn’t mean it is true.
13
Minimalism
Pragmatic Theory: A statement ‘S’ is true if and only if S
E.g. “Grass is green” is true if and only if grass is green
Pros: 1) It seems to capture the main insight of the
correspondence theory. 2) It allows us to avoid seeing truth as a
deep metaphysical issue. 3) It allows us to see how truth is
useful to human beings.
Cons: 1) It is susceptible to the liar’s paradox
“This sentence is false”.
14
Key Concepts- Truth
The Liar’s Paradox
Liar Sentence: “This sentence is false.”
Assumption 1: the liar sentence is true
It says that it is false.

So, it has to be false too (given Assumption 1).
Assumption 2: the liar sentence is false
The sentence says that it is false.
So, it has to be true too (given Assumption 2)
15
Key Concepts- Truth
Liar Sentence: “This sentence is false.”
So, either way, the liar sentence is both true and false.
But, it is incoherent to assert that ANY sentence is both true
and false. But our reasoning seems good and our premises seem
to be true. So where is the problem?
This is the Liar’s paradox
16
Key Concepts- Truth
So, while we all have a common sense understanding of what
truth (and falsity are), the concept of truth leads to some serious
philosophical questions.
17
Key Concepts- Claims/Statements
Now that we have discussed truth, we can move on to the
concept of a claim / statement.
Declarative Sentence: A sentence that attempts to describe (or

declare something about) reality.
“Grass is green”.
“There are 200 hundred people in this room”
NOT questions or exclamations or imperatives or greetings
18
Key Concepts- Arguments
An argument has statements as parts. There are two:
Premise(s)
Conclusion
Definition 1: An argument is a group of statements where some
of the statements (the premises) give us a reason to believe one
of the other statements(the conclusion)
Why is this a bad definition?
19
Key Concepts- Arguments
Definition 2: An argument is a group of claims where some of
the statements(the premises) are intended to give us a reason to
believe one of the other statements(the conclusion)
20
What makes these true?
“Pizza tastes delicious”

“Sushi is gross”
“The taste and texture of rotten milk is disgusting”
All of these are true/false relative to each person’s beliefs
This is called: Subjective Relativism about Taste
21
“If someone lets you go before them while driving, it is polite
to raise your hand thanking the other driver.”
“It is polite to bow to your superiors.”
“It is polite to burp loudly at the dinner table to show one’s
thanks for a delicious meal.”
22
“If someone lets you go before them while driving, it is polite
to raise your hand thanking the other driver” is true relative to
American culture
“It is polite to bow to your superiors” is true relative to
Japanese culture
“It is polite to burp loudly at the dinner table to show one’s
thanks for a delicious meal” is true relative to Culture X
So, statements about politeness are true/false relative to a
culture’s beliefs.
This is called Social Relativism about Etiquette/Politeness

23
Subjective / Social Relativism
So far, so good. Relativism seems to provide a good explanation
of why statements about taste or etiquette are true/false.
But is relativism a good explanation of why ALL statements are
true/false? Probably not.
Moral Judgments
Scientific Statements
Digression: Moral Language
Moral Language
“Torturing 4 year olds for fun is wrong.”
“Having an abortion is ok.” / Having an abortion is
permissible”.
“You shouldn’t lie!” / “Telling the truth is the right thing to do”
These are examples of moral judgments
25
“Torturing a four year old child merely for fun is morally
wrong”
“Genocide is morally wrong”

26
“Torturing a four year old child merely for fun is morally
wrong”
“Genocide is morally wrong”
Subjective Relativism about Moral Judgments?
Is it really plausible to think that Genocide is morally right if
you believe that it is? I don’t think so.
Social Relativism?
It also doesn’t seem plausible to think that Genocide is morally
right just because the Nazis believed it was.
27
“Earth is closer to the sun than Jupiter”
“Human Beings have lungs”
Subjective Relativism?
Social Relativism?
28
Global Subjective/Social Relativism
So, what we can call “global subjective relativism” (i.e. the idea

that all statements are either true or false relative to the beliefs
of each individual person) is false.
Furthermore, it would seem that global social relativism would
also be false for the same reasons—it cannot adequately explain
the truth/falsity of scientific statements.
29
Chapter 3
Deductive vs. Inductive Arguments
Is this an argument?
“God exists.”
*
NO!
“Obviously God exists.”
*
NO!

“I believe in God. I grew up in a religious family.”
*
NO!
“God exists. After all, something had to create the universe.”
*
Yes!
An argument has two parts!
Remember…
*
The conclusion-part.
The part that tries to support or prove it—the premise-part.
The engine (of my cheap car) burns oil.Therefore, it will be
really expensive to fix.Therefore we should buy a new car.
Often the conclusion of one argument is a premise in a second
argument.
*

Another complication>>>>>>>
*
Arguments can have an unstated premise!
*
“You aced the midterm;
therefore, you will pass the course.”
*
Unstated assumption (premise): People who ace the midterm
will pass the course.
“You aced the midterm, and people who ace the midterm will
pass the course.”
A conclusion may also be implied:
Implied conclusion?
“You will pass the course.”
*

Two kinds of argument:
Inductive vs. Deductive
New topic:
*
In an argument, the premise(s) (a group of statements) are
intended to support the conclusion (another statement).Since
there are different kinds of support, there are different kinds of
argument.
Remember…
*
Sometimes we try to provide conclusive support for believing a
statement.Ex.If I’m not dreaming right now, then we are all in
Rosemead. I’m not dreaming. So, we are all in
Rosemead.Deductive Argument
*
On the other hand, sometimes we only try to provide probable
support for a statement.Ex.90% of the time there is traffic in
Rosemead on weekdays at 6pm. I’ll leave Rosemead today at
6pm. So, I’ll be in traffic today.Inductive Argument

*
I intend to support a statement conclusively= Deductive Arg.
I intend to support a statement probalistically= Inductive Arg.
Deductive vs. Inductive Arguments
*
Good deductive arguments have 2 qualities. Good deductive
arguments are both:1) Valid
and2) Have true premises
When is a Deductive Argument good?
*
The premises of a valid argument provide conclusive support
for the conclusion.An argument is valid when: it is impossible
for (a) the premises to be true AND (b) for the conclusion to be
false.Ex. If I eat an apple, then I eat a fruit. Napoleon is eating
an apple. So, Napoleon is eating a fruit.
Valid Arguments
*
A sound argument is a valid argument with true premises.If you
give a sound argument, you prove your conclusion conclusively.

Sound Argument
*
Good inductive arguments also have 2 qualities. Good inductive
arguments are:1) Strong
and2) Cogent
When is an Inductive Argument good?
*
© 2012 McGraw-Hill Higher Education. All rights reserved.
© 2012 McGraw-Hill Higher Education. All rights reserved.
The premises of a strong argument probable support for the
conclusion.An argument is strong when: the conclusion is likely
to be true provided that the premises are true
Strong Arguments
*
A cogent argument is a strong argument with true premises.If
you give a cogent argument, you give probabilistic reason to
believe the conclusion.
Cogent Argument
*
Two Kinds of Argument

DeductiveAttempts to provide conclusive supportValidIf
premises are true, conclusion must be true.SoundValid + true
premises
InductiveAttempts to provide probable supportStrongIf premises
are true, then the conclusion is probably true.CogentStrong+
true premises
*
Two Arguments for God’s Existence
Kalaam Cosmological ArgumentP1: Everything that begins to
exist has a cause.P2: The universe began to existC: The
universe has a cause (namely,God)
Argument from DesignP1: Many features of the universe appear
to have been designed.C: The universe has a designer (namely,
God)
*
DeductiveValidSound?InductiveStrong?
Exam 1: Sample Test Questions
33. Determine whether the following passage contains an
argument and, if it does, identify that argument’s final
conclusion.

“I seriously doubt many people want to connect up their TV to
the Internet. For one thing, when people watch TV they don’t
want more information. For another thing, even if they did, they
wouldn’t be interested in having to do something to get it. They
just want to sit back and let the TV tell them what’s
happening.”
Answer: Argument. Conclusion: It is doubtful many people
want to connect their TV to the Internet.
conclusion.
“Here’s how you make chocolate milk. Warm up a cup of milk
in the microwave for two minutes, then add two tablespoons of
the chocolate. Stir it up, then stick it back in the microwave for
another 30 seconds. Then enjoy it.”
Answer: No argument.
conclusion.
“The P/E ratio is the number of dollars of stock you have to buy
to get one dollar of profit. Any stock with a ratio greater than
15:1 is overpriced. That’s why it’s not a good idea to invest in
stocks right now. P/E ratios are way too high.”
Answer: Argument. Conclusion: It’s not a good idea to invest in
stocks right now.

conclusion.
“Your jacket looks a little tattered, there, Houston. Time to get
a new one, I’d say.”
Answer: Argument. Conclusion: Time to get a new jacket.
conclusion.
“Should I go to class today? We’re probably just going over the
test; I can afford to miss that. Besides, I haven’t cut a single
class all semester. I guess it won’t hurt to stay home this once.”
Answer: Argument. Conclusion: It won’t hurt to stay home this
once.
conclusion.
“You’ve got every reason to add another telephone line, despite
the cost. The way it is now, you tie up your phone for hours
while you’re on your computer. If people need to reach you in
an emergency, they can’t do it.”
Answer: Argument. Conclusion: You’ve got every reason to add
another telephone line.

conclusion.
“Pretzels are pretty good for a snack food. But it’s wise to keep
in mind that they are high in sodium, at least if you eat the
salted kind.”
conclusion.
“Can you believe it? Tight-fitting polyester clothes are making
a comeback. They’ve even brought back bell-bottoms. Next
thing you know, the professors around here will be dragging out
their leisure suits.”
9. Identify the following passage as containing an argument,
two arguments, or no argument; if it contains an argument,
identify the conclusion(s); and, if it contains two arguments,
indicate which argument is the principal argument.
“Hey, see that bald dude over there? You know how old that
guy is? He’s my teacher.”
“I dunno, fifty, maybe.”
“He’s not fifty, he’s almost seventy!”
“Must eat a lot of Grow Pup.”
“I guess! He’s a good teacher, too. He really communicates.
Makes you remember stuff. I forget now what the course was. . .
.”
Answer: Argument; the conclusion is that he’s a good teacher.

10. Identify the following passage as containing an argument,
two arguments, or no argument; if it contains an argument,
identify the conclusion(s); and, if it contains two arguments,
indicate which argument is the principal argument.
“If you don’t mow your lawn at least once a week, what
happens is that when you do mow it, it’ll turn brown later.”
Answer: An argument in most contexts, for the unstated
conclusion that you ought to mowyour lawn at least once a
week.
11. Supply a general principle that, assuming it is true, makes
the following into a relatively strong inductive argument:
Sydney is ten; therefore she likes horses.
Answer: "Ten-year-olds" like horses.
28. The word “so” introduces
a. a conclusion.
b. a premise.
c. sometimes a conclusion and sometimes a premise.
Answer: a
29. Consider: “ X . Therefore, since Y ,
Z .” Which would go in the “Y” space?
a. a premise
b. a conclusion
Answer: a
Chapter 3
Determine whether the claim in the following is too vague in

the context that is stated or implied: From the label of a can of
spaghetti sauce: “Made with real meat.”
Answer: Too vague, if you care what kind of meat goes into
your spaghetti.
64. Determine whether the claim in the following is too vague
in the context that is stated or implied: Teacher to student:
“How long should your term paper be? As long as it takes to do
justice to your subject.”
Answer: Too vague. (How does your instructor’s standard
answer to this question compare?)
32. “Sheila’s clarinet is French. It’s a Leblanc, and all Leblanc
instruments are made in France.”
This argument is best taken as
a. inductive
b. deductive.
Answer: b
33. If we know that a valid argument has true premises, then
the argument
a. must be sound.
b. might be sound.
c. is strong.
d. might have a false conclusion.
Answer: a

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