Transcript Definitions and Arguments - Michael Johnson's Homepage

Definitions and Arguments
Extensions
If something is a cat, and I call it “a cat” then I
have correctly applied the word “cat” to it.
The extension of a word is all the things that the
word correctly applies to.
The extension of ‘cat’ is all of the cats.
Definitions
A definition is an attempt to explain the
meaning of a word by using a different word or
phrase that has the same meaning.
The word being defined is called the
definiendum (Latin for “to be defined”).
The word or phrase doing the defining is called
the definiens (Latin for “defining”).
Extensional Adequacy
Definitions should be extensionally adequate,
meaning that the definiens and the definiendum
should correctly apply to exactly the same
things. Compare:
“A bachelor is a man.”
“A bachelor is an unmmaried man.”
Extensional Adequacy
However, just because two things have the same
extension does not mean that one of them is a
good definition of the other. Compare:
“A renate is an animal with kidneys.”
“A renate is an animal with a heart.”
Reportative Definitions
The most common type of definition is a
“reportative definition.” This is a definition that
gives the meaning of a word as it is actually used
by speakers of the language.
Dictionaries
You might think that dictionaries contain mostly
reportative definitions, but this is not true:
much of the time they do not actually present
definitions.
Example: ‘red is the color of ripe tomatoes’
Subtlety
One reason that dictionaries don’t contain
definitions is that their goal is not a great degree
of accuracy, but instead informing you how to
use a word.
A dictionary might say, “religion is belief in a
superhuman controlling power.” This works
most of the time, except in unusual scenarios.
Jargon
Another concern with using dictionaries to
determine the meaning of a word is that
sometimes words have special meanings to
certain groups of people.
If you’re in a conversation with a philosopher
and they use the words “free will,” they will
mean something different than what’s in the
dictionary.
Stipulative Definition
A stipulative definition does not report the
meanings of words as they are actually used.
Instead it introduces a new meaning, either for
an already existing word, or for a new, made-up
word.
Spotting Stipulative Definitions
There are many ways people have of indicating
that they are stipulating a meaning:
• “Let us define X as…”
• “In what follows, we will understand X to
mean…”
• “Suppose we say that a thing is X when…”
Purposes of Stipulative Definitions
Sometimes there is not a word for what you
want to talk about, so you have to invent one.
Science and math are full of words with
stipulative definitions. (“prime,” “composite,”
“whole,” “continuous”…)
Precising Definitions
Precising definitions are a combination of
reportative and stipulative definitions. This is
when you take the normal meaning of a word,
and stipulate some aspects of its meaning.
“Criminals cannot apply for this job.”
“Students get a set lunch discount.”
Using Precising Definitions
Precising definitions can often be used to resolve
certain arguments.
“If by ‘marriage’ you mean that gays can have a
religious ceremony, live together, and call each
other ‘spouse’ then yes, gays can get married in our
country; but if you mean by ‘marriage’ a
recognition by the government and society of the
validity of such a relationship, then they cannot.”
Persuasive Definitions
Persuasive definitions are definitions that get
the correct meaning of a term, but not the
correct emotional impact of it. The term is
neutral, but the persuasive definition adds a
positive (or negative) dimension to it.
Example
Example from Hurley (2008):
• definition supporting taxation: “the procedure
by means of which our commonwealth is
preserved and sustained”
• definition opposing taxation: “the procedure
used by bureaucrats to rip off the people who
elected them”
Problems
Persuasive definitions (as you would expect) can
persuade people to change their minds or to
support a particular view. But they do not do
this with a good argument– instead they
convince with emotional impact. Having a strong
emotional reaction to something is not a reason
for supporting it or being against it.
Evaluating Definitions
As we’ve seen, definitions can play an important
role in understanding arguments, resolving
arguments, and misleading people.
It is thus important to understand how they can
go wrong, and how they can get things right.
Example: Too Wide
Some definitions are “too wide.” This is a
metaphor about the definition’s extension. A
definition is “too wide” when it includes all the
things in the word’s extension plus some other
stuff.
“A small business is a business with less than 25
workers.”
Example: Too Narrow
A definition is “too narrow” when it includes
only some of the things in the word’s extension.
“A Christian is someone who believes that the
Bible is the word of God. Therefore, allowing gay
marriage discriminates against Christians,
because the Bible says that homosexuality is
wrong.”
Example: Neither (Both?)
“A restaurant is a place where one can eat.”
You can eat in your house, or in a park. So there
are places where one can eat that are not
restaurants.
There are restaurants one cannot eat at, for
example takeaway restaurants.
Circular Definitions
The Law and Definitions
Definitions are particularly important in legal
contexts. Often laws are written in ways that
don’t foresee certain strange events, and they
either technically apply or don’t apply, when
that’s not what we want or expect.
“Using” A Gun
In the US, there are higher penalties for drug
crimes when people involved in the crime “use”
a gun.
But what happens if you trade your gun for
drugs? Is that a “use”?
Smith v. US: person giving gun uses it.
Watson v. US: person receiving gun does not.
“Occurrence”
On 11 September 2001, hijackers flew two
planes into the World Trade Center towers in
New York City. The towers collapsed and almost
3,000 people died.
The lessee of the towers, Larry Silverstein, had
insurance up to $3.5 million USD ($27m HKD) for
any “occurrence” that damaged the buildings.
“Person”
Suppose the government wants more people
per car, so that less pollution is emitted for every
person transported. They open up a lane in the
road for cars with 2 or more people in them.
You’re not allowed to drive in the lane if you’re
the only “person” in your car. Now suppose that
you’re pregnant? Can you drive in the lane?
Verbal Disputes
Some arguments are “purely verbal” and
depend on the meanings of words. Some are
“factual” and depend on what the facts are.
William James gives an example of a purely
verbal dispute involving a man chasing a squirrel
around a tree.
James’ Squirrel
“Which party is right depends on what you
practically mean by ‘going round’ the squirrel. If
you mean passing from the north of him to the
east, then to the south, then to the west, and
then to the north of him again, obviously the
man does go round him, for he occupies these
successive positions…”
James’ Squirrel
“…But if on the contrary you mean being first in
front of him, then on the right of him then
behind him, then on his left, and finally in front
again, it is quite as obvious that the man fails to
go round him... Make the distinction, and there
is no occasion for any farther dispute.”
Ambiguity
An ambiguous word is a word with more than
one meaning.
‘Bank’ in English can mean a financial institution
or the side of a river.
Sometimes sentences can be ambiguous even if
none of their words are. “Flying planes can be
dangerous.”
Vagueness
A vague word is not ambiguous– it has only one
meaning. But it can be unclear whether it
applies in any particular circumstance:
•
•
•
•
Tall
Rich
Bald
Beautiful
Usefulness of Vagueness
Vague words are useful for communication. It’s
better to have a word ‘tall’ for describing people
than a word that means ‘over 1.8 meters.’
First, we might not know whether someone is
over 1.8 meters. Second, we might not care
about information so specific. Finally, we might
want to call children ‘tall’ if they are tall for their
age.
When to Avoid Vagueness?
Even though vagueness is useful, it sometimes
causes trouble.
Vague policy recommendations are often
completely unhelpful. If student reviews say
“the class is hard,” it’s difficult to tell how hard it
is, or in what ways. If someone says we need
“better hospitals” we don’t know what counts.
Difficulty of Confirming Vague
Statements
Furthermore, people can use vague statements
to avoid responsibility for what they’re saying.
Distortion
No TRUE Scotsman
Teacher: You didn’t get an A because you didn’t
work hard.
Student: But I did work hard, I studied five hours
every day, came to class and office hours…
Teacher: But you didn’t REALLY work hard,
because people who REALLY work hard get A’s.
ARGUMENT ANALYSIS
Arguments
An ‘argument’ in philosophy is not a quarrel or
dispute, instead it is a number of premises that
are given in support of a conclusion.
Indicating Premises
•
•
•
•
•
•
since
firstly, secondly, ...
for, as, after all,
assuming that, in view of the fact that
follows from, as shown / indicated by
may be inferred / deduced / derived from
Indicating Conclusions
•
•
•
•
therefore, so, it follows that
hence, consequently
suggests / proves / demonstrates that
entails, implies
Hidden Assumptions
Unlike arguments written in logic and proved
using our formal logical systems SL and PL,
arguments in ordinary language don’t always
state all their assumptions.
Example #1
Assumption: If people make fun of religious
beliefs, then religious people will have their
feelings hurt.
Hidden Assumption: It should be illegal to hurt
people’s feelings.
Conclusion: It should be illegal to make fun of
religious beliefs.
Example #2
Assumption: My opponent wants to increase
social welfare programs.
Assumption: Social welfare programs help
minorities more than other people.
Conclusion: His agenda is to help minorities at
the expense of the rest of us.
Example #3
Assumption: Lots of students talk with one
another very loudly in class.
Assumption: If lots of students do something,
then it’s OK to do.
Conclusion: It’s OK if I talk to my friends loudly
in class.
Analogies
An analogy is when you take two different things
and compare them in some respect.
“Life is like a box of chocolates: you never know
what you’re going to get.”
Analogical Arguments
An analogy is often used as the premise in an
argument. “X is like Y; Y is Z; therefore X is Z.”
Analogical Arguments
The universe is a complex system of interacting
parts that serve a purpose.
A watch is a complex system of interacting parts
that serve a purpose.
If we found a watch by itself in the wilderness
we’d assume that some intelligent designer had
made it.
Therefore we should assume that an intelligent
designer made the universe.
Analogies as Insults
Analogies are sometimes used solely as smear
tactics, with no real intellectual purpose.
American musician Hank Williams Jr. said that
John Boehner playing golf with Barack Obama
was “like Netanyahu playing golf with Hitler.” All
this analogy does is suggest that Obama is like
Hitler.
Analogy to Arguments
Analogies provide an important way of showing
that arguments are bad:
Person #1: The Iraq invasion was good; many
Iraqis (e.g. Kurds) supported it.
Person #2: That argument is like this one:
Hitler’s invasion of Czechoslovakia was good;
many Czechs supported it.