Foundations of Logical Reasoning-Module 1 Review

Thinking

A cognitive activity that we use in an attempt to gain knowledge or to understand something. Thinking has a purpose.

Logic

The study of methods and principles used to distinguish correct and incorrect forms of reasoning. Differenetiates between correct from incorrect reasoing, sound arguments from unsound arguments, and valid arguments from invalid arguements.

Argument

A set of propositions in which some of the members of the set, premises, are offered in evidential support of another member of the set, the conclusions.

Propositions

They are expressed through declarative sentences, building blocks of reasoning; units of thought or speech; are either true or false.

Premises

Propositions that are offered in evidence for the conclusion.

Conclusion

The proposition that the premises are offered in support of

Narrative

People simply describing a sequence of events, organized in accordance with their occurrence.

Descriptive Passage

An author relates a series of facts about something, may be organized in some way, but there is no argument

Recognizing and Explicating Arguments

Recognizing an argument means noticing it, explicating an argument means writing out the sentence that make up the argument and clearly identifying the conclusion

Paraphrasing Arguments

They state their premises clearly and all we have to do is write them down, the arguments we have looked at thus far have been simple. Some arguments require changing the wording when explicating, also make sure all sentences in our explication are declarative sentences

Paraphrasing Arguments: Enthymemes

An argument that is stated incompletely.

PP: Identify Argument and Conclusion- ¨Consider the following passage: The only spiders that can survive in this environment are Phoneutria fera. Only the female of that species is venomous. The spider on the wall must therefore not be venomous. For the female Phoneutria fera can easily be identified by the spots that run across its back, and that spider over there has no spots. This passage...

(a)contains an argument; the first sentence is its conclusion

(b)contains an argument; the second sentence is its conclusion

(c)contains an argument; the third sentence is its conclusion

(d)contains an argument; the fourth sentence is its conclusion

(e)does not contain an argument

C

PP: Identify Argument and Conclusion-

¨Consider the following passage: Carolyn seems to lose her purse whenever she goes to the cinema. I wonder if she's lying to us. Maybe she's actually giving her money away to someone or not going to the cinema at all? I'll ask her about it tonight. This passage....

a: Contains an argument; the first sentence is its conclusion

b: contains an argument; the second sentence is its conclusion

c: contains an argument; the third sentence is its conclusion

d: contains an argument; the fourth sentence is its conclusion

e: does not contain an argument

E

PP: Enthymeme

-Consider the following enthymeme: Abigail is majoring in education. Abigail wants to be a teacher. Which of the following premises should be added to create a charitable reconstruction of the argument?

(a)Abigail's mother is a teacher

(b)Most people who major in education want to be teachers

(c)All people who major in education want to be teachers

(d)All people who want to be teachers major in education

(e)Abigail is pursuing a degree at university

B

PP: Enthymeme

-¨Consider the following enthymeme: All humans are partly responsible for global warming. Janet is a human. Which of the following statements should be added as a conclusion to create a charitable reconstruction of the argument?

(a)Janet is responsible for global warming

(b)Janet is not a cat

(c)Global warming is a hoax

(d)Janet is partly responsible for global warming

(e)Janet is a climate change denier

D

Does Truth/False apply to arguments?

No, arguments are either; good or bad, valid or invalid, correct or incorrect, sound or unsound

Does Truth/False apply to propositions?

Yes, a propositions will either be truth or false. Propositions CANNOT be both or NEITHER

Deductive Argument

An argument is an argument that attempts to provide premises that gurantee and necessitate its conclusion

Inductive Argument

An argument that attempts to produce premises that make the conclusion probably or more likely.

What is the difference between a Deductive Argument vs an Inductive Argument?

Differ in the relationship they posit between premises and conclusions. They also differ in Logical Strength

Examples for a Deductive Argument to be valid:

-It's premises guarantee its conclusion

-If its premises are true, then the conclusion must also be true

-It is impossible for the premises to be true and the conclusion false

-IF an argument is valid and you accept the premises, then you MUST accept the conclusion

Does Truth Apply to Arguments?

No. Only applies to propositions. Validity applies to arguments

How can you demonstrate that an argument is invalid?

-Identify its form.

-Identify an argument with the same form where the premises are TRUE and the conclusion FALSE

-The new argument is a counterexample

An argument is invalid when........

the truth of the premises does not guarantee the truth of the conclusion

A valid argument.....

-Can have true premises and a true conclusion

-can have false premises and a false conclusion

-can have false premises and a true conclusion

A valid argument CANNOT.....

Have true premises and a false conclusion

How do you know if an argument is sound?

It must be a valid argument that has nothing but true premises

Are all valid arguments sound arguments?

No. Remember, a sound argument is a valid argument with all true premises.

Where might you find Inductive Arguments?

In science, because just like science, arguments can be revised if new evidence is discovered.

An inductive argument is strong.....

if the truth of the premises make the truth of the conclusion highly probably

An inductive argument is weak.....

If the truth of the premises DO NOT make the truth of the conclusion highly probably

PP: Identifying Argument Type-

¨Consider the following passage: When Luca and Angelo play board games they always get into arguments. Luca just got the board game Monopoly down from the shelf. Thus, there's going to be an argument pretty soon. This passage

(a)does not contain an argument

(b)contains an argument that is best classified as sound

(c)contains an argument that is best classified as deductive

(d)contains an argument that is best classified as inductive

(e)contains an argument that is best classified as a counterexample

D

PP: Identifying Argument Type-

¨Consider the following passage: Mandy and Milly are both in detention. The only teacher who gives detention at this school is Mr. Francis. So, Mr. Francis must have put Mandy and Milly in detention. This passage

(a)does not contain an argument

(b)contains an argument that is best classified as sound

(c)contains an argument that is best classified as deductive

(d)contains an argument that is best classified as inductive

(e)contains an argument that is best classified as a counterexample

C

PP: Strengthening Arguments-

¨Consider the following argument: Granddad is taking us out for dinner. So, we'll go to Pizza Express. Suppose the premise "Granddad likes pizza" is added. What effect would this have on the argument?

(a)The additional premise would strengthen the argument

(b)The additional premise would make the argument inductive

(c)The additional premise would weaken the argument

(d)The additional premise would make the argument valid

(e)The additional premise would have no effect upon the argument

A

PP: Strengthening Arguments-

¨Consider the following argument: I have a bag of marbles, two-thirds of which are black and a third of which are blue. If I pull out a marble from the bag at random, it will be black. Suppose the premise "Charlie has removed half of the black marbles" from the bag is added. What effect would this have on the argument?

(a)The additional premise would strengthen the argument

(b)The additional premise would make the argument inductive

(c)The additional premise would weaken the argument

(d)The additional premise would make the argument valid

(e)The additional premise would have no effect upon the argument

C

Premise Indicators

-Since

-For

-Because

-For

-As

-Follows from

-As shown be

Conclusion Indicators

-As a result

-Clearly

-Thus

-Consequently

-Its obvious that

-Therefore

-Hence

-So

How do you recognize an argument?

-arguments try to prove something

-they are trying to convince you of something

-they are NOT merely listing facts