Lesson test: Validity against truth

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Validity against truth

1.[2p]
A valid argument guarantees

that if the premises are true the conclusion is true

Correct

that the premises are true

The answer is: that if the premises are true the conclusion is true

that the conclusion is true

The answer is: that if the premises are true the conclusion is true

that the argument will persuade someone

The answer is: that if the premises are true the conclusion is true

2.[2p]
An argument that assumes its own conclusion as a premise is valid.

True

Correct

False

The answer is: True

3.[3p]
What is wrong with a circular argument, given that it is valid?

It cannot move anyone from premises they accept to a conclusion they do not

Correct

Its conclusion is false

The answer is: It cannot move anyone from premises they accept to a conclusion they do not

It breaks the rule of conditional proof

The answer is: It cannot move anyone from premises they accept to a conclusion they do not

Its premises contradict each other

The answer is: It cannot move anyone from premises they accept to a conclusion they do not

4.[3p]
"Nothing is better than eternal happiness; a ham sandwich is better than nothing; so a ham sandwich is better than eternal happiness." What has gone wrong?

Equivocation: "nothing" is a quantifier in one premise and treated as a name in the other

Correct

Affirming the consequent

The answer is: Equivocation: "nothing" is a quantifier in one premise and treated as a name in the other

The premises are inconsistent

The answer is: Equivocation: "nothing" is a quantifier in one premise and treated as a name in the other

The conclusion has been denied rather than affirmed

The answer is: Equivocation: "nothing" is a quantifier in one premise and treated as a name in the other

5.[2p]
What is an argument with a suppressed premise called? One word.

CorrectNot quite: enthymeme

6.[3p]
Match each informal fallacy to the premise it hides.

False dilemma
Slippery slope
Appeal to authority
Straw man

the claim that the weakened version is the opponent's
a conditional saying this person's endorsement settles it
a chain of conditionals whose links are unsupported
a disjunction that is not exhaustive

Show the answer

False dilemma: a disjunction that is not exhaustive Slippery slope: a chain of conditionals whose links are unsupported Appeal to authority: a conditional saying this person's endorsement settles it Straw man: the claim that the weakened version is the opponent's

7.[3p]
Which of these are limits on logic established in the twentieth century?

Select all that apply

First-order validity is undecidable

Correct

Arithmetic is incomplete

Correct

Truth is not definable in the language it is about

Correct

Valid arguments can have false premises

The answer is: First-order validity is undecidable, Arithmetic is incomplete, Truth is not definable in the language it is about

8.[3p]
Relevance logic differs from classical logic by rejecting

the inference of anything at all from a contradiction

Correct

conditional proof

The answer is: the inference of anything at all from a contradiction

universal elimination

The answer is: the inference of anything at all from a contradiction

the material conditional's truth table entirely

The answer is: the inference of anything at all from a contradiction

9.[3p]
Why is formalisation not something an algorithm can do for you?

English carries tense, causation and intention that the notation has no place for

Correct

The rules of translation have not been discovered yet

The answer is: English carries tense, causation and intention that the notation has no place for

Formulas are too long to generate

The answer is: English carries tense, causation and intention that the notation has no place for

Every English sentence has exactly one translation

The answer is: English carries tense, causation and intention that the notation has no place for

1.[2p] A valid argument guarantees

2.[2p] An argument that assumes its own conclusion as a premise is valid.

3.[3p] What is wrong with a circular argument, given that it is valid?

4.[3p] "Nothing is better than eternal happiness; a ham sandwich is better than nothing; so a ham sandwich is better than eternal happiness." What has gone wrong?

5.[2p] What is an argument with a suppressed premise called? One word.

6.[3p] Match each informal fallacy to the premise it hides.

7.[3p] Which of these are limits on logic established in the twentieth century?

8.[3p] Relevance logic differs from classical logic by rejecting

9.[3p] Why is formalisation not something an algorithm can do for you?

1.[2p]
A valid argument guarantees

2.[2p]
An argument that assumes its own conclusion as a premise is valid.

3.[3p]
What is wrong with a circular argument, given that it is valid?

4.[3p]
"Nothing is better than eternal happiness; a ham sandwich is better than nothing; so a ham sandwich is better than eternal happiness." What has gone wrong?

5.[2p]
What is an argument with a suppressed premise called? One word.

6.[3p]
Match each informal fallacy to the premise it hides.

7.[3p]
Which of these are limits on logic established in the twentieth century?

8.[3p]
Relevance logic differs from classical logic by rejecting

9.[3p]
Why is formalisation not something an algorithm can do for you?