Lecture 5

Question 1

What is Cogency?

Answer 1

An argument is cogent if and only if it is not valid, but if all the

premises are true, the conclusion is probably true

Otherwise, the argument is non-cogent.

Question 2

Example of cogent argument

Answer 2

1. Quitting smoking tends to improve one’s health.
2. Mary has quit smoking.

Therefore, probably, her health will improve

Question 3

What is a Non-Cogent Argument?

Answer 3

possible but not likley

Question 4

does a cogent argument have to be true?

Answer 4

a cogent argument doesn’t have to have a true premises, and it doesn’t have to have true conclusions either: what’s important is the relation between premise and conclusion.

Question 5

What is an example of a cogent argument

Answer 5

1. Most chairs have ten legs.
2. Prime Minister Justin Trudeau is a chair.

therefore, probably Trudeau has 10 legs.

This argument has two false premises and a false conclusion … but,

nevertheless, it’s what we call cogent.

Why?

if the premises were true, the conclusion would be probable.

Question 6

What is the cogency test?

Answer 6

**Imagine/suppose that the premises are all true. Assuming this, is the

conclusion likely to be true as well?

If the answer is “yes”, then the argument is cogent

If the answer is “no”, then the argument is non-cogent

Question 7

A Cogent Argument Can Have

Answer 7

• all true premises, true conclusion
• all true premises, false conclusion
• one or more false premises, true conclusion
• one or more false premises, false conclusion

Question 8

When testing for cogency what is main issue?

Answer 8

it’s whether the premises, if all true, would make the conclusion probable.

Question 9

1 cogent Argument Pattern

Answer 9

1. Most A’s are B’s
2. X is an A
3. therefore, probably, X is a B
4. Most profs have PHD
5. Kraay is prof
6. therefore Kraay has a PHD

Question 10

Another cogent argument pattern

Answer 10

1. X is an A
2. X is a B
3. Most AB’s are C’s
   therefore X is a C
4. Kraay is right handed
5. Kraay is a professor
6. Most right handed profs are nice
   therefore, it’s likely that kraay is nice

Question 11

Some common patterns of Non-Cogent Argument?

Answer 11

1. Most A’s are B’s
2. X is not A
3. X is not B

Most professors have PhD’s
Zola has a PhD
Therefore, probably, Zola is a professor

Question 12

What is validity like?

Answer 12

Validity is like an On- Off switch.

Question 13

What is cogency like?

Answer 13

just like a dimmer.

Question 14

What is deductive strength?

Answer 14

a) Valid,

b) rational/ justified/ reasonable for the person to beleive that all of the argument’s premises are true, based on the available evidence.

Question 15

How can a deductive argument be weak?

Answer 15

a) invalid

b) not rational/ justified

c) both a+b

Question 16

Can a valid argument be strong? weak?

Answer 16

yes

Question 17

Can a strong argument can’t be invalid?

Answer 17

no. a strong argument by definition is valid.

Question 18

What is inductive strength?

Answer 18

• An argument is inductivley strong…
  
  • cogent
  • rational resonable/ justified
  • not defeated by a person’s total evidence

Question 19

Can a cogent argument be strong? weak?

Answer 19

yes.

Question 20

Can an inductively strong argument be cogent?

Answer 20

by def it must be strong. And can’t be weak.

Question 21

If a argument passes the first step of cogency test, but it’s not true. is the argument strong?

Answer 21

no, because it’s not reasonable

Question 22

can we measure cogency?

Answer 22

yes, cogency comes in degrees. The more reasonable something is, the more likely it is to happen.

Question 23

Someone coming walking in with new evidence in court to make a suspect inocent is an example of?

Answer 23

being defeated by a person’s total evidence

Question 24

An inductive argument has to be

Answer 24

probable