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Critical Thinking > Module 3A > Flashcards

Module 3A Flashcards

1
Q

Support (Technical Notion)

Term: Support
Definition:

A
  1. Support is a technical notion in argument evaluation referring to the

DEGREE PROBABILITY THAT THE TRUTH OF THE CONCLUSION FOLLOWS THE TRUTH OF THE PREMISES.

It is a RELATIONSHIP BETWEEN PREMISES AND CONCLUSIONS, BASED ON HOW LIKELY THE CONCLUSIONS ARE IF THE PREMISES WERE TRUE.

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2
Q

Characteristics of Support: 4

A
  1. SUPPORT is EXPLAINED in TERMS OF TRUTH BUT DIFFERS FROM THE TRUTH OF THE PREMISES.
  2. PREMISES CAN OFFER COMPLETE SUPPORT TO CONCLUSIONS EVEN IF THE PREMISES ARE FALSE IN THIS TECHNICAL SENSE.
  3. SUPPORT = is a MATTER OF DEGREE , representing the PROBABILITY OF A GIVEN CONCLUSION, GIVEN THE TRUTH OF THE PREMISES.

It’s CRUCIAL TO UNDERSTAND THAT ‘FLASE PREMISE’ CAN PROVIDE ‘STRONG OR COMPLETE SUPPORT’ TO A CONCLUSION IN THIS TECHNICAL USAGE.

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3
Q

How do you judge the degree of support given by premises to a conclusion?

A

By abandoning independent knowledge of the truth or falsehood and asking,

‘Supposing the premises are true, how probable does this make the conclusion true?’

The degree of improbability of true premises and a false conclusion is the degree of support.

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4
Q

What is the relationship between the probability of premises supporting a conclusion and the improbability of the conclusion being false?

A

The probability that premises give to a conclusion’s truth is the same as the improbability they give to its falsity.

The degree of support is estimated by considering the improbability of the conclusion being false if the premises are true.

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5
Q

How can you classify the degree of support?

A

Complete (100%), strong, moderate, weak, nil (0%).

The more unlikely the conclusion is false if the premises are true, the stronger the support.

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6
Q

Provide an example of an argument with weak support for its conclusion.

How does the number of tosses in a coin example affect the degree of support?

A

“Three successive random tosses of this coin have all come down heads; so something is biasing the outcome.”

It gives very weak support.

MORE TOSSES GIVE STRONGER SUPPORT.
For instance, “Thirty successive random tosses of this coin have all come down heads; so something is biasing the outcome” provides very strong support.

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7
Q

What questions can be useful in estimating the likelihood of possibilities?

A

Questions like
- ‘Would a fundamental scientific law have to be false for the premises to be true and the conclusion false?’

help assess support. REALISTIC POSSIBILITIES WEAKEN SUPPORT.

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8
Q

Provide a rule of thumb for assessing support.

A

THE MORE REALISTIC THE POSSIBILITY OF A SITUATION WHERE THE PREMISES ARE TRUE AND THE CONCLUSION FALSE

= THE WEAKER THER SUPPORT.

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9
Q

Define deductive validity.

A

Deductive validity, or simply validity, is COMPLETE SUPPORT

where the TRUTH OF THE PREMISES GUARANTEES THE TRUTH OF THE CONCLUSION.

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10
Q

Can an argument be deductively valid with false statements?

A

Yes, an argument can be deductively validEVEN IF EVERY STATEMENT IN IT IS FALSE.

Deductive validity ONLY REQUIRES THE IMPOSSIBILITY OF COMBINING TRUE PREMISES AND A FALSE CONCLUSION.

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11
Q

What kind of impossibility is required for deductive validity?

A

LOGICAL impossibility is required for deductive validity.

This involves a CONTRADICTION , where attempting to describe a state of affairs results in ASSERTING AND DENYING THE SAME THING.

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12
Q

Provide an example of a deductively valid argument with false statements.

A

Napoleon Bonaparte died in 1902; hence he was alive in the twentieth century.”

This is deductively valid despite the false statement, as the definition requires the impossibility of true premises and a false conclusion.

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13
Q

What is a contradiction in logical terms?

A

A contradiction is when you both assert and deny the same thing.

It may be EXPLICIT (e.g., ‘Hitler smoked and Hitler did not smoke’) or IMPLICIT, reducible to an explicit contradiction through definition.

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14
Q

How do you test for deductive validity?

A
  1. Extract the premises and conclusion from the argument, create a conjunction of all premises with the negation of the conclusion, and check for the presence of a contradiction.
  2. If a contradiction exists, the argument is not deductively valid.
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15
Q

Why are violations of scientific laws and well-known truths not necessarily logically impossible?

A

Violations of scientific laws and well-known truths may be impossible in some sense but not logically impossible because they do not involve contradictions in their descriptions.

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16
Q

Why do violations of scientific laws and well-known truths not necessarily involve contradictions?

A

Violations of scientific laws and well-known truths may be impossible in some sense other than logically impossible, and their descriptions do not necessarily involve contradictions.

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17
Q

Why is the guarantee provided by the premises in the given argument not absolute?

A

The guarantee provided by the premises in the argument about Ian’s actions is not absolute because violations of scientific laws and truths, while very strong, do not ensure an absolute guarantee due to the possibility of scenarios without logical contradictions.

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18
Q

Provide an example of a deductively invalid argument.

A

“Ian just this very moment took a normally fatal dose of cyanide and immediately jumped off the top of the Eiffel Tower, cutting his arteries as he leapt and pulling the pin from the grenade in his pocket as he fell, so he’ll shortly be dead.”

The argument is deductively invalid, despite being very strong, as there is a logical possibility of Ian surviving.

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19
Q

Is support a matter of degree or is it binary?

A

Support is a matter of degree.

It can be complete or not, with any degree of support less than complete counting as invalidity.

20
Q

Define deductive validity.

A

Deductive validity means that the premises entail the conclusion, imply the conclusion, and the conclusion follows from the premises.

It is not a matter of degree.

21
Q

What is the difference between formal validity and non-formal validity?

A

Formal validity can be captured in formal logic calculi and is characterized by certain patterns of inference being valid regardless of subject matter.

Non-formal validity may depend on the specific content of the argument.

22
Q

What is a central concept in mathematical proof and formal logic?

A

Deductive validity is a central concept in mathematical proof and formal logic.

23
Q

What is the relation between formal logic and actual reasoning?

A

Formal logic, similar to the relation of algebra to arithmetic, arose from the observation that some inferences are deductively valid in virtue of their form rather than content.

24
Q

Who devised the earliest formal logic, and what is it known as?

A

Aristotle devised the earliest formal logic known as SYLLOGISTIC OR CATEGORICAL LOGIC.

25
Q

What does the earliest formal logic, syllogistic logic, focus on?

A

Syllogistic logic focuses on forms displaying the internal structure of statements,

such as ‘All S are M; no M are P; therefore, no S are P’.

26
Q

What is a more recent formal logic described by Govier in Chapter 8?

A

The propositional calculus

is a more recent formal logic described by Govier in Chapter 8.

27
Q

What is the common form shared by two arguments in the propositional calculus?

A

A common form is ‘P or Q; not-P; so, Q’, known as DISJUNCTIVE SYLLOGISM, where the italicized capitals indicate positions for complete statements.

28
Q

How do some arguments support their conclusions?

A

Some arguments SUPPORT THEIR CONCLUSIONS BY VIRTUE OF THE RELATION OF THE CONTENT OR MEANING OF THE PREMISES AND CONCLUSIONS, RATHER THAN THROUGH SPECIFIC FORMS.

29
Q

Why can’t the argument concerning Napoleon be symbolized in categorical logic?

A

The argument concerning Napoleon cannot be symbolized in categorical logic, and in the propositional calculus (‘P, therefore Q’), any indication of validity disappears.

This indicates the reliance on the content or meaning of the premises and conclusions.

30
Q

What is needed for a strong argument in terms of support?

A

A degree of support no less than strong is needed for a strong argument.

31
Q

Is it always reasonable to demand complete support for an argument?

A

It is not always reasonable to demand complete support for an argument, and it must be emphasized that some invalid arguments can be very strong.

32
Q

Provide an example of a non-valid argument that is strongly supported

A

An example is the argument from a sample of marbles to the conclusion that the whole original collection is composed in the same proportions.

It’s not valid, but the conclusion is extremely strongly supported by the premise concerning the sample.

33
Q

How does Govier break down the notion of support in the ARG Conditions?

A

Govier breaks down the notion of support into Relevance and Grounds in the ARG Conditions, where irrelevant premises give no support at all to their conclusion.

34
Q

How does Govier characterize irrelevant premises in terms of support?

A

Govier characterizes irrelevant premises as those that provide support of degree 0 to the conclusion.

35
Q

Why does the division into Relevance and Grounds add unnecessary complication?

A

The division into Relevance and Grounds adds unnecessary complication because premisses irrelevant to a conclusion can be conceptualized as giving support of degree 0, covering all cases with a single notion.

36
Q

How does Govier suggest thinking about support in terms of a continuum?

A

Govier suggests thinking of support in terms of a continuum between 0 and 100%, covering all cases with a single notion, rather than dividing it into Relevance and Grounds.

37
Q

What is the argument made about valid arguments in relation to support?

A

It is mentioned that valid arguments are simply those whose premises provide 100% support for the conclusion, but using the term ‘ARGV Conditions’ doesn’t make a snappy phrase.

38
Q

“A false premiss can give complete support to a conclusion.”

A

True

Let’s get a few things clear. It is not true that the moon is made of cheese. And it is not true that pigs can fly. Right? Ok, good. Now that we have that sorted, take a look at this argument:

  1. If the moon is made of cheese, then pigs can fly.
  2. The moon is made of cheese.

SO,

  1. Pigs can fly.

The argument is unsound, because, (obviously) 2 is false. But, if 1 and 2 were both true, it would be impossible for 3 to not be true as well. The premises (1 and 2) when taken together–and despite the fact that at 2 is false–give complete support to the conclusion (3).

39
Q

“A false premiss can give only weak, not strong, support to a conclusion.”

A

False

When we are evaluating the degree to which the premises of an argument support the argument’s conclusion, we put aside the question of whether or not the premises are actually true. What we do instead is ask ourselves this question:

if the premises were true, how likely would that make the conclusion?

It should be clear then that a premise which is actually false, just like a premise which is actually true (or whose truth or falsity is unkown) can support the conclusion of an argument to any degree. i.e., not at all, weakly, moderately, strongly, completely.

40
Q

“A false premiss cannot give any support to a conclusion.”

A

False

41
Q

“Deductive validity has nothing to do with the acceptability of premises.”

A

True

42
Q

“Deductive validity requires all premisses to be true.”

A

False

Here is a counterexample:

  1. If France is not in Europe, then Germany is in the southern hemisphere.
  2. France is not in Europe.

So,

  1. Germany is in the southern hemisphere.

At least one of the premises is false. But the argument is certainly deductively valid, having the form of Modus Ponens.

43
Q

“Deductive validity requires the conclusion to be true.”

A

False

44
Q

“If, when you assume that the premisses are true and the conclusion is false, you have constructed a contradiction, then the argument is valid.”

A

true

45
Q

“The more likely it is that the premisses are true if the conclusion is true, the stronger the degree of support between premisses and conclusion.”

A

False

Close. “True” would have been the correct answer if the sentence had read:

“The more likely it is that the conclusion is true if the premises are true, the stronger the degree of support between premises and conclusion.”

46
Q

An argument whose premisses and conclusion are all true __________ a good argument.

A

may be

Evaluating arguments involves two things.
(1) Assessing the acceptability of the premises, and

(2) assessing the degree of the support that the premises give to the conclusion.

If we know that the premises and conclusion are true, that is not enough to make a determination about how good the argument is.

This is because knowing that the premises are true and that the conclusion is true doesn’t tell us anything about how well the premises support the conclusion.

All we can say is that the argument might be a good argument.

47
Q

The less realistic the possibility of a situation in which the premisses are true and the conclusion false, then the __________ the support.

A

stronger

Critical Thinking (18 decks)

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