Philosophy
6: Logic in Practice
Los Angeles Pierce College
Department of History, Philosophy, & Sociology
Lecture Notes for "Chapter One" and "Chapter Two" of Porter's The Voice of Reason
Lecture Notes for
"Chapter One" of Porter's The Voice
of Reason
Contradictory Statements
"'All generalizations
are false.'"
"'There's an
exception to every rule'"
"The French novelist
Albert Camus once remarked that the minute we declare 'Everything is absurd' we
contradict ourselves, for we have said something meaningful"
"No one goes to that
club anymore, it's too crowded"
Seeming Contradictions
Contradiction Paradox
"Paradoxes are
statements that appear to be inconsistent, absurd, or opposed to common sense
but may be true in a special or deeper sense"
Contradiction Oxymoron
"An oxymoron is a
figure of speech in which opposite or incongruous words are put together to
express a point more pungently"
Trying it Out
I. 2
II. 3
II. 5
IV. 2
V. 1
V. 8
VI. 1
VI. 3
VII. 6
VII. 10
Using vs. Mentioning Terms
Referring to what words
(may) represent, using those words
Referring to words
themselves
Use
Mention
"a map is not the
land itself"
"if 'strawberries' were mentioned as something found in a
dictionary, it would be a waste of time trying to find them there to eat with
cream and sugar."
Quotation
Marks
"To avoid
miscommunication we must use quotation marks to signal that we are mentioning a
word"
"otherwise people
will assume we are using it in the customary way"
Trying it Out
IV. 2
IV. 4
Lecture Notes for
"Chapter Two" of Porter's The
Voice of Reason
Part One of Chapter Two
Why Words
Logical analysis demands
the clear use of words
Understanding the
"basic elements that make up words" will help us in our future
logical analyses.
The Basic Ingredients
Intension Extension
Connotation
Intension
Extension
The See-Saw
Intension varies inversely
with extension
Larger and Smaller
The larger the intension,
the smaller the extension, and vice versa
Small intension:
a herbivorous
mammal
four legged
Large extension: cows, gazelles, horses, etc.
Larger intension:
a
herbivorous mammal
four
legged
solid
hoofed
Smaller extension: cows, gazelles, horses, etc.
What's What
"knowing the
distinction between intension and extension helps us understand such phrases as
'business is business,' 'boys will be boys,' [etc.]"
Business E.G.
E.G. "Business is business"
Extensional-business
(commerce, competition, exchange, etc.) is intensional-business
(money-making activity aimed at profit)
Trying it Out
I. 9
I. 10
II. 1
II. 9
III. 3
III. 4
IV. 3
IV. 7
IV. 10
Connotation
Emotional associations
connected to a word explicit meaning of a word
"When you hear me on
those other stations that's just industry businessÐbut when you hear me on Fake
93.2Ðnow that's family."
Trying it Out
V. 1
V. 2
V. 6
VI. 3
VII. 3
VII. 5
VIII.
XI. 1. d
XI. 2. a
XI. 2. c
Part Two of Chapter Two
Vagueness
"Vague words or
expressions lack clarity and distinctness, so that we don't know whether they
apply in a given case."
Acceptable Vagueness
Aristotle: "We must not expect more precision
than the subject-matter admits"
Vagueness as a Charge
Word use that is
unnecessarily vague is to be avoided
The charge of vagueness
comes from using unnecessarily vague words
Charge
E.G. "suppose we ask a used car salesman
how much a car costs and we are told it's a bargain, a very good deal, less
expensive than we might think, priced to move, sure to save us money, and so
forth."
The Ought for Vagueness
Avoid vagueness as much as
possible for the sake of clarity, even when vagueness is unavoidable
Trying it Out
I. 3
I. 4
II. 2
II. 3
Ambiguity
"In ambiguity a word
contains several meanings, and we are uncertain which one is meant."
In ambiguity, "[w]e are confused about the word,
phrase, sentence, or passage because it can be understood in more than one
sense."
Multiple Meanings of Words
Many words have more than
one meaning
"Go to the bank"
Ambiguity as a Fact of Language
In context, not a problem
"Go to he bank and deposit money into
your savings account"
"Go to the bank and
cast your line in"
Ambiguities Semantic & Ambiguities Syntactic
Semantic syntactic
Neutral Semantic Ambiguity
"Semantic ambiguity
has to do with the multiple meanings of a word as it appears in a sentence,
either once or twice."
Single Use Semantic Ambiguity
"Bikinis now sold for
a ridiculous figure"
Double Use Semantic Ambiguity
"'Time flies like an
arrow, but fruit flies like a banana (and fireflies like the wind)'"
Ambiguity as a Positive Tool
Ambiguity is not
necessarily bad, and necessarily a mere fact of language, it can be a tool
"In philosophy, I am
a tool too!"
My favorite
ambiguity:
"I confuse
easily"Ðcopyright me!
Ambiguity as a Charge
When the context does not
settle the meaning, and you're not trying to tell a joke, you are open to being
(negatively) charge with being ambiguous
Negative Semantic Ambiguity
"'All committed
people will get out the vote,
'John has just been
committed,
'therefore John will get
out the vote'"
Pernicious Semantic Ambiguity
The right to bear arms
extends to whom?
Semi-Neutral Semantic Ambiguity
Accent
"Under the broad
category of semantic ambiguity the phenomenon of accent should also be
mentioned."
"Here ambiguity
occurs because it is unclear which word in the sentence is being accented or
emphasized."
Accent E.G. Banks
"The bank robber
Willie Sutton was asked, 'Why do you rob banks?' and he answered, 'Because
that's where they keep the money.'"
Accent E.G. Harm
"'You should not harm
someone who has harmed you' might mean be taken to mean that you ought not
return injury for injury (we should turn the other cheek), or maybe that we
should harm someone who has not harmed us."
Syntactic Ambiguity
"Syntactic ambiguity
occurs when the grammatical arrangement of words makes the meaning of a
sentence unclear."
"The meaning of each
word may be plain but we cannot understand the overall sense."
"Eat here and get
gas"
"Hospitals Are Sued
by Seven Foot Doctors"
"Save soap and waste
paper"
"In 'Save soap and
waste paper,' we do not know whether 'waste' is an adjective or a verb"
Negative Syntactic Ambiguity
Amphiboly
"'If John loves his
family more than his mistress, then he is a good man,
'but John's mistress loves
his family more than he does,
'therefore John is not a
good man.'"
Instead
"'If John's mistress
loves his family more than he does then he is a good not a man,
'but John loves his family
more than his mistress,
'therefore John is a good
man.'"
Take Away Be aware of these differences and don't let
them get in the way of your use of language
Trying it Out
IV. 4
IV. 6
V. 7
VI. 3
VI. 5