Chapter 4 Flashcards
In logic we are concerned with evidence of truth in a proposition. this evidence is______
A conclusion
The evidence in support of these conclusions consists of other propositions, which are termed _______
Premises
In order to support a conclusion, one must use other propositions or ____.
Premises
For each ______ we must identify the premises that provide the evidence for that ______[same as above]____ and those premises should be distinct propositions.
conclusion, conclusion
A set of premises together with a conclusion is an _____
Argument
In logic an argument is made up of what?
A set of premises (or other propositions that provide the evidence for a conclusion) and a conclusion
In an argument the conclusion is ____ from the premises
Inferred
In logic a synonym for argument is____
Inference
Conclusion indicators include:
Thus Therefore So Consequently As a result Which means that Hence Which means that Which implies that
Premise indicators include:
Since Because As For Given that Assuming that In as much as The reason that In view of the fact
The author doesn’t just tell the reader what they think to be true, they also present _____ which are intended to convince the reader that it is true.
Reasons
Examples in this chapter involve different types of reasoning, but they also illustrate a common pattern. In each case we are concerned with evidence for the truth of some proposition. In logic, this proposition is called a _____. The evidence in support of these _______ consists of other propositions called premises. Thus each of our examples involves the use of premises to support a ______.
this proposition is called a conclusion
…support of the conclusions
to support a conclusion
Examples in this chapter involve different types of reasoning, but they also illustrate a common pattern. In each case we are concerned with evidence for the truth of some proposition. In logic, this proposition is called a conclusion. The evidence in support of these conclusions consists of other propositions called ______. Thus each of our examples involves the use of_______ to support a conclusions.
premises
A set of premises together with a conclusion is called an ______.
argument
In logic, an argument is a set of …..
a set of premises with a conclusion
In everyday speech, argument is often used to mean a quarrel between two people. But it is also
used to mean…..
an appeal to evidence in support of a conclusion in logic
______ means a set of propositions in which some propositions (the premises) are asserted as support or evidence for another (the conclusion).
Argument
A conclusion is inferred from the ________. Thus an argument can also be described as an _____.
premises
inference
We can think of the premises as the raw materials for an argument and the conclusion as the final product. To understand an argument, we need to know what happens in between—on the factory floor, so to speak. We need to analyze the inner workings of the argument, the individual steps that lead from premises to conclusion. Once we have analyzed the argument, we can go on to ______ it: Is it a good argument? Does it provide
a good reason to accept the conclusion?
evaluate it
There are two main steps in reviewing an argument. They are…
analyzing and evaluating
An _____ pointing from premise to conclusion represents a single step in reasoning—the relationship between a premise and the conclusion.
an arrow
In some cases, the premises are _____ on one another: Two or more premises work together to make a single argument for a conclusion.
dependent
In other cases, the premises are ______: They do not work together; each one offers a separate line of support for the conclusion.
independent
When we put premises together in order to create an argument—meaning they are dependent on each other. We represent this fact by using a second symbol ____ , to join the premises.
the plus (+) sign
When premises independently support the conclusion we would diagram the argument by using _____ to join each
premise to the conclusion separately.
arrows
In an argument with independent premises, two (or more) arrows will converge on the conclusion. But can we have the opposite situation? Can we have arrows diverging
from a single premise to two or more different conclusions? That is, can a single face serve as evidence for more than one conclusion?
Certainly
In everyday chinking, as well as in science and ocher academic subjects, we often find chains of ______
inferences (or arguments)
For example, if someone opposes gun control on
the ground that it violates the right of self-defense, we might ask: Why assume people have such a right? The person might answer: Because people have a right to life,
and therefore have a right to defend it/themselves. So we have four propositions to deal with, which are
- People have a right to life.
- People have a right to defend their lives.
- Gun control violates the right of self-defense.
- The government should not restrict gun ownership.
- People have a right to life.
- People have a right to defend their lives.
- Gun control violates the right of self-defense.
- The government should not restrict gun ownership.
How would this be diagrammed?
1 —–> 2+3 ——-> 4
Strategy for diagramming arguments (or inferences):
- An argument must have at least one ____ and one ____; use an arrow to represent the link between them .
at least one premise and one conclusion
Strategy for diagramming arguments (or inferences):
- An argument must have at least one premise and one conclusion; use an_____ to represent the link between them .
an arrow
Strategy for diagramming arguments (or inferences):
- A single conclusion may be supported by more than one_____; use a plus sign and a single arrow for dependent premises, convergent arrows for independent ones.
premise
Strategy for diagramming arguments (or inferences):
- A single conclusion may be supported by more than one premise; use a _____ and a single arrow for dependent premises, convergent _____ for independent ones.
use a plus sign (+)
convergent arrows for independent ones
Strategy for diagramming arguments (or inferences):
- A single premise may support more than one ______; draw divergent arrows.
conclusion
Strategy for diagramming arguments (or inferences):
- A single premise may support more than one conclusion; draw ______ _____.
divergent arrows
Strategy for diagramming arguments (or inferences):
- An argument may have more than one step, so that a given proposition can be both a conclusion (of one step) and a premise (of another step}; use ______ to represent each step, with the final conclusion on the bottom line.
separate arrows
The basic standard to evaluation is that an _____ is good to the extent that it provides evidence for the truth of its conclusion.
argument
The basic standard of evaluation is that an argument is good to the extent that it provides ______ for the truth of its conclusion.
evidence
What is the goal to reasoning?
the goal of reasoning is to determine the truth or falsity of propositions that we are not in a position to verify directly by sense perception.
To provide evidence for a conclusion, an argument must have two essential attributes.
First, its premises must be _____.
True
An argument is an attempt to establish the truth of a proposition by relating it to facts we already know. So we have to start from facts; false premises don’t prove anything.
To provide evidence for a conclusion, an argument must have two essential attributes.
Second, the premises must be logically related to the conclusion in such a way that if the premises are true, the conclusion is likely to be ______ as well.
true as well.
In other words, it is not enough that the premises be true; they must also support the conclusion. They must provide evidence that the conclusion is true.
Consider this argument:
(1) All fish breathe through gills, and (2) whales are fish. Therefore (3) whales breathe through gills.
Premise 2 is false. Nevertheless, the conclusion follows from the premises ; if both premises were true, the conclusion would have to be true as well.
There are many types of arguments which are….
Inductive and deductive
Deductive arguments….
A deductive argument is an argument that is intended by the arguer to be deductively valid, that is, to provide a guarantee of the truth of the conclusion provided that the argument’s premises are true. This point can be expressed also by saying that, in a deductive argument, the premises are intended to provide such strong support for the conclusion that, if the premises are true, then it would be impossible for the conclusion to be false.
A _____ argument is an argument that is intended by the arguer to be _______ly valid, that is, to provide a guarantee of the truth of the conclusion provided that the argument’s premises are true. This point can be expressed also by saying that, in a ______ argument, the premises are intended to provide such strong support for the conclusion that, if the premises are true, then it would be impossible for the conclusion to be false.
Deductive
Deductively
Deductive
An argument in which the premises do succeed in guaranteeing the conclusion is called a _____ or valid argument.
deductive
Here is a valid ____ argument:
It’s sunny in Singapore. If it’s sunny in Singapore, then he won’t be carrying an umbrella. So, he won’t be carrying an umbrella.
deductive
Here is a mildly strong ________ argument:
Every time I’ve walked by that dog, it hasn’t tried to bite me. So, the next time I walk by that dog it won’t try to bite me.
inductive
An _______ argument is an argument that is intended by the arguer to be strong enough that, if the premises were to be true, then it would be unlikely that the conclusion is false. So, an ______ argument’s success or strength is a matter of degree.
inductive
There is no standard term for a successful inductive argument, but this article uses the term “_____.” Inductive arguments that are not ______ are said to be weak; there is no sharp line between _____ and weak.
Strong
Logicians often describe inductive arguments as _____. The conclusion ______ or goes beyond what the premises state
Ampliative
Amplifies
Which of the following is an argument?
Select one:
a. The boss always rewards hard work, but punishes laziness.
b. He straightened his tie carefully, as he did every morning.
c. Since cheerleading is physically demanding, it should be considered a sport.
d. Amanda was able to buy a new car because she got a promotion at work.
e. Since the blizzard of 2002, it has never snowed in our town.
c. Since cheerleading is physically demanding, it should be considered a sport.
Which of the following is an argument?
(I) It will probably rain tomorrow because a cold front is moving in.
(II) It rained yesterday because a cold front moved in.
Select one:
a. both I and II
b. only I
c. neither
d. there is not enough information to know
e. only II
b. only I
Generalization is:
Select one:
a. interrupting while someone else is trying to explain an argument
b. applying a general rule to a particular case
c. drawing a conclusion without any evidence to support it
d. arguing in a vague way without specifying what you mean
e. drawing a conclusion about a class of things by observing a sample of the class
e. drawing a conclusion about a class of things by observing a sample of the class
For which argument below are the premises dependent?
Select one:
a. Premises: The car stalled twice last week. The car has a malfunctioning headlight.
Conclusion: The car will need to go to the repair shop soon.
b. Premises: Sarah has very light skin. Sarah has blue eyes.
Conclusion: Sarah is of Northern European descent.
c. Premises: Penguins have feathers. Penguins have beaks.
Conclusion: Penguins are birds.
d. Premises: Bill always says hello. Bill has many friends.
Conclusion: Bill is very social.
e. Premises: Politics depends on morality. Morality depends on religion.
Conclusion: Politics depends on religion
e. Premises: Politics depends on morality. Morality depends on religion.
Conclusion: Politics depends on religion.
Which of the following premises provides the strongest support for the conclusion that Harry is a lousy driver?
Select one:
a. Harry has poor vision and can’t tell the brake pedal from the accelerator.
b. Harry was involved in a major accident.
c. Harry failed driver’s ed three times.
d. Harry got a parking ticket.
e. Harry once dinged his door in a parking lot.
a. Harry has poor vision and can’t tell the brake pedal from the accelerator.
The observation that “Harry has poor vision and can’t tell the brake pedal from the accelerator” provides objective, direct, explicit evidence that Harry is not a good driver. Good vision (at least, non-poor vision) is necessary for good driving, and knowing how the pedals function is also necessary.
The fact that Harry was in an accident tells us very little about his driving. The accident could have been another driver’s fault.
The fact that Harry failed Driver’s Ed three times is not very informative, for it may have been a very bad teacher, Harry may have had other more important obligations during the course, etc.
Getting a parking ticket does not relate to Harry’s actual driving skill, and likewise for getting his door dinged in a parking lot.
For which argument below are the premises independent?
Select one:
a. Premises: Spinach contains iron. This omelet contains spinach.
Conclusion: This omelet contains iron.
b. Premises: Laser eye surgery is getting cheaper. Cheaper goods have greater appeal.
Conclusion: Laser eye surgery is becoming more appealing.
c. Premises: The rule of law allows people to know the consequences of their actions. The rule of law is fair to all people.
Conclusion: The rule of law is a worthy idea.
d. Premises: Lagos is in Nigeria. Nigeria is in Africa.
Conclusion: Lagos is in Africa.
e. Premises: Japan has a thriving electronics industry. Any country with a thriving electronics industry is wealthy.
Conclusion: Japan is wealthy.
c. Premises: The rule of law allows people to know the consequences of their actions. The rule of law is fair to all people.
Conclusion: The rule of law is a worthy idea.
If there are two strong arguments, can one be stronger than the other?
Select one:
a. No, because every argument is strong in its own way.
b. Yes, because one might have more importance.
c. No, because all arguments are equally strong.
d. No, because arguments can’t really be compared to each other.
e. Yes, because one might support its conclusion better.
e. Yes, because one might support its conclusion better.
For which argument below are the premises independent?
Select one:
a. Premises: It is not safe to smoke around an oxygen tank. Your friend is smoking near that oxygen tank.
Conclusion: You should tell your friend to move away from the tank.
b. Premises: Yoga is very relaxing. Relaxation would improve my heart health.
Conclusion: Yoga would improve my heart health.
c. Premises: The newspaper should cover all important stories. The election is an important story.
Conclusion: The newspaper should cover the election.
d. Premises: The river’s water level is falling. Fish require a high water level.
Conclusion: The river’s fish are endangered.
e. Premises: My mother says I have a nice smile. My father says I have a nice smile.
Conclusion: I have a nice smile
e. Premises: My mother says I have a nice smile. My father says I have a nice smile.
Conclusion: I have a nice smile
DEDUCTIVE ARGUMENT
The premises are an attempt to guarantee the truth of the conclusion.
Component propositions are repeated, or subjects
and predicates within propositions are repeated, in the argument to make information already contained in the premises explicit (note explicit info may not be obvious). There are many forms of deductive arguments, e.g., “modus ponens”:
How would you write this into an equation:
If P, then Q
P
Therefore, Q
If an argument is valid, then the ______ must be true if the _____ are true
then the conclusion must be true if the premises are true; i.e., the truth of the premises guarantees the truth of the conclusion. Otherwise, the argument is invalid.
