Validity & Soundness

Question 1

Conditional statement

Answer 1

If ‘p’ then ‘q’ : Asserts that something is true based on a certain condition

Question 2

Antecedent

Answer 2

The “p” in the conditional statement formula - where “q” is claimed to be true

Question 3

Consequent

Answer 3

The “q” in the conditional statement formula - what is claimed to follow if ‘p’ is true

Question 4

Deductive argument

Answer 4

Claims that the premises provide logically conclusive support for the conclusionVALID or INVALID

Question 5

Inductive argument

Answer 5

Claims that the premises provide probably support for the conclusionSTRONG or WEAK

Question 6

Valid argument

Answer 6

A deductive argument that succeeds in providing conclusive support for its conclusion

Question 7

Invalid argument

Answer 7

A deductive argument that fails to provide conclusive support for its conclusion

Question 8

Sound argument

Answer 8

Deductively valid argument with true premises

Question 9

Truth-preserving

Answer 9

Defining characteristics of valid deductive argument: their structure guarantees that if the premises are true so also are the conclusions

Question 10

Strong argument

Answer 10

Inductive argument that provides highly probable support for its conclusion

Question 11

Weak argument

Answer 11

Inductive argument that fails to provide strong support for its conclusion

Question 12

Cogent argument

Answer 12

a strong, inductive argument with all premises true

Question 13

Dependent premise

Answer 13

Must be combined with one or more other premises to support the conclusion

Question 14

Independent premise

Answer 14

Provides support for the conclusion on its own

Question 15

Syllogism

Answer 15

Deductive argument consisting of two premises and one conclusion

Question 16

Common valid deductive forms

Answer 16

1. Affirming the antecedent2. Denying the consequent3. Disjunctive syllogism4. Hypothetical syllogism

Question 17

Affirming the antecedent

Answer 17

if ‘p’ then ‘q’, ‘p’; therefore ‘q’If Spot barks, a burglar is in the house. Spot is barking. Therefore, a burglar is in the house.

Question 18

Denying the consequent

Answer 18

If ‘p’ then ‘q’, not ‘q’; therefore not ‘p’If it rains, the sidewalk gets wet.But the sidewalk’s not wet. So, it must not have rained

Question 19

Disjunctive syllogism

Answer 19

Either ‘p’ or ‘q’, not ‘p’; therefore ‘q’The number 3 is either even or odd. However, it is not even. Therefore, it is odd

Question 20

Hypothetical syllogism

Answer 20

If ‘p’ then ‘q’, if ‘q’ then ‘r’; therefore if ‘p’ then ‘r’If Guy steals the money, he will go to jail.If Guy goes to jail, his family will suffer.Therefore, if Guy steals the money, his family will suffer.

Question 21

Common invalid deductive forms

Answer 21

1. Affirming the consequent2. Denying the antecedent

Question 22

Affirming the consequent

Answer 22

Invalid deductive formIf ‘p’ then ‘q’, ‘q’; therefore ‘p’

Question 23

Denying the antecedent

Answer 23

Invalid deductive formIf ‘p’ then ‘q’, not ‘p’; therefore not ‘q’“If today is Tuesday we have logic class. Today’s not Tuesday. Hence, we don’t have logic today.”

Question 24

What do good arguments do?

Answer 24

Appeal to reason - they show that it is reasonable to accept the conclusions given the premises

Question 25

Two forms of agrument

Answer 25

1. Deductive argument2. Inductive argument

Question 26

Example of deductive arguments

Answer 26

“Im taller than Aimee. Aimee is taller than Melissa. So I’m taller than Melissa.’-> If the premises offered really are true, then the conclusion must also be true

Question 27

A rule in invalid arguments?

Answer 27

It is a deductive argument that fails to provide conclusive support for its conclusion.ALTHOUGH - It is still possible for the premises to be true and yet the conclusion to be false.

Question 28

How to evaluate soundness of an argument

Answer 28

1. Are the premises true?2. Do those premises lead to the conclusion?

Question 29

Example of false premises that still support the given conclusion.

Answer 29

Pigs have wings (P). Any animal with wings can fly (P). So, pigs can fly (C).This argument is VALID but UNSOUND.

Question 30

Example of true premises that don’t support the conclusion

Answer 30

Birds have wings (P). Bats have wings (P). Therefore, birds are bats (C).

Question 31

Is the conclusion guaranteed in inductive reasoning?

Answer 31

No. Not intended to be

Question 32

Induction

Answer 32

The process of building inductive arguments

Question 33

Cogency

Answer 33

An inductively strong argument with true premises is said to be cogent.(Like the soundness of deductive arguments)

Question 34

4 Steps in judging arguments

Answer 34

1. Find the arguments conclusion and then premises.2. “Is it the case that if the premises are true then the conclusion must be true?”-> if yes: VALID DEDUCTIVE-> if premises are true: SOUND-> Instances where the premises are true while conclusion is false: INVALID (then go to step 3)3. “Is it the case that if the premises are true, its conclusion is probably true?”->if yes: Inductively strong-> are premises probably true?: Cogent too-> if NO: go to step 44. “Is the argument intended to offer (a) conclusive or (b) probable support for its conclusion (but fails to do so)?”-> If (a): invalid deductive argument->If (b): weak and inductive argument

Question 35

Deductive indicator works

Answer 35

absolutely, certainly, it necessarily follows

Question 36

Inductive indicator words

Answer 36

Probably, likely, odds are, chances are

Question 37

Steps to finding missing premises

Answer 37

Step 1: Search for credible premises that would make the argument validStep 2: Search for a credible premise that would make the argument as strong as possibleStep 3: Evaluate the reconstructed argument

Question 38

Example of a conditional statement

Answer 38

“If I won the lottery then I’d pay all my debts”

Question 39

Argument flow charts

Answer 39

Always flow downward on the page (Premises at top, conclusion on the bottom)Boxes: PremisesCircles: ConclusionArrows: Connect them

Question 40

Diagramming independent premises

Question 41

Diagramming dependent premises

Question 42

Multi-staging of arguments

Question 43

Assesing long arguments - 4 steps

Answer 43

1. Study the text2. Find the conclusion3. Identify the premises4. Diagram the argument