6. Logical and analytical thinking

Question 1

Deductive reasoning

Answer 1

process of reasoning from one or more statements (premises) to reach a logically certain conclusion

Rather than going beyond given evidence to discover something new, it often involves verifying what is already known

Can be only 1 conclusion for these premises, if these true premises allow for alternative conclusions, then the deduction is not valid

Question 2

Logical tasks:

Categorical reasoning/syllogism

Answer 2

type of logical argument in which a pair of sentences serve as the premises and a third sentence as the conclusion

it is about whether certain things belong in certain categories

Question 3

Logical task:

Syllogism

Answer 3

kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two or more propositions that are asserted or assumed to be true

Question 4

Logical task:

Types of categorical syllogisms:
Universal affirmative

Answer 4

All A are B

relationship between the two categories is universal for all members (whole inclusion)

types of relationship: subordination (a is larger category b is a subcategory) class identity (a=b)

eg:
Premise 1: All humans are mortal.
Premise 2: All philosophers are humans.
Conclusion: Therefore, all philosophers are mortal.

Question 5

Logical task:

Types of categorical syllogisms:
Particular affirmative

Answer 5

Some A are B

some members of one category are partially also members of another category

types of relationship: subordination, class identity, intersection and inclusion

eg:
Premise 1: Some birds can fly.
Premise 2: All parrots are birds.
Conclusion: Therefore, some parrots can fly.

Question 6

Logical task:

Types of categorical syllogisms:
Universal negative

Answer 6

No A are B

Absolutely no overlap between categories

eg:
Premise 1: No reptiles are mammals.
Premise 2: All snakes are reptiles.
Conclusion: Therefore, no snakes are mammals.

Question 7

Logical task:

Types of categorical syllogisms:
Particular negative

Answer 7

Some A are not B

some members of one category are nor members of another category

types of relationship:
intersection, inclusion and exclusion

eg:
Premise 1: Some mammals are not carnivores.
Premise 2: All whales are mammals.
Conclusion: Therefore, some whales are not carnivores.

Question 8

Syllogisms validity

Answer 8

• if a syllogism leads to more than one conclusion, the deduction is invalid
• Venn diagrams are used to assess the validity of a syllogism

Question 9

Context errors in categorical reasoning

Answer 9

• Atmosphere effect: false statement is assumed true because it is introduced among true statements
• Theme effects: reasoning is not independent of content. Can be based exclusively on their beliefs, without applying logical reasoning (belief bias)
• Misinterpretation of premises: degree of ambiguity, select one of the possible interpretations

Question 10

Conditional reasoning:

Answer 10

Reasoning about conditionality and causality

Question 11

Conditional reasoning:
Common conectives

Answer 11

If… then
either… or
neither… nor

Question 12

Conditional reasoning:
Valid rules

Answer 12

Correct in all cases

• Modus Ponens (MP) - affirming the antecedent:
  if it rains, then the streets are wet; it rains, therefore, the streets are wet
• Modus Tollens (MT) - denying the consequent:
  if it rains, then the streets are wet; the streets are not wet, therefore, it does not rain

Question 13

Conditional reasoning:
Paradoxical rules

Answer 13

Not correct in all cases

• Denying the antecedent (DA):
  if it rains, then the streets are wet; it does not rain, therefore, the streets are not wet
• Affirming the consequent (AC):
  if it rains, then the streets are wet; the streets are wet, therefore, it rains

Question 14

Conditional reasoning:

Wason Card Selection Task

Answer 14

• Indicate nº of cards to turn over in order to verify the rule (from: A K 2 7)
• Premise: If a card has a vowel on one side, then it has an even number on the other side
• Solution: A (affirming antecedent) and 7 (denying the consequent)

Question 15

Conditional reasoning:

Wason Card Selection Test
What errors does it test?

Answer 15

Theory of confirmation bias, but now also human reasoning in abstract logic, social conduct and other semantic contexts, especially content effect.

• Confirmation bias: selective thinking, looking for what confirms our beliefs. Ignore, not look for what doesn’t
• Pairing bias: choose cards named in the premise (a and 4)
• Content bias: bias (more mistakes, abstract content), facilitatory effects (create scenario where easier)