reasoning 1

Question 1

what is conditional reasoning

Answer 1

How the words in connecting propositions (‘connectives’) influence inferential reasoning

Question 2

what are “if-then” propositions

Answer 2

Premise in 2 parts (2 clauses): ‘if’ and ‘then’
‘if’: antecedent part/clause
‘then’: consequent part/clause
Information statement
‘therefore’ (or similar word): conclusion

Question 3

what are the 4 types of inferences

Answer 3

Modus ponens (MP)
Or: Affirmation of antecedent
Modus tollens (MT)
Or: Denial of consequent

Affirmation of consequent (AC)
Denial of antecedent (DA

Question 4

what are the 2 logically valid types of inferences

Answer 4

2 logically-valid (comply with principles of logic):
Modus ponens (MP)
Or: Affirmation of antecedent
Modus tollens (MT)
Or: Denial of consequent

Question 5

what are the 2 logically invalid types of inferences

Answer 5

2 logically-invalid (fallacious/non-logical):
Drawing logically-incorrect conclusion from premises
Affirmation of consequent (AC)
Denial of antecedent (DA

Question 6

how does modus ponens work (Cat argument)

Answer 6

Antecedent (if P): cat sitting on mat
Consequent (then Q): dog barking
Draw logically-valid conclusion… 
Dog barks 
…by affirming antecedent…
Cat sitting on mat
…based on statement of fact/observation
Cat sitting on mat

Question 7

how does modus tollens work (Telephone’ argument)

Answer 7

‘Telephone’ argument:
Antecedent (if P): telephone working
Consequent (then Q): dialling tone
Draw logically-valid conclusion…
Telephone not working 
…by denying consequent… 
(not a) dialling tone
…based on statement of fact/observation
No dialling tone

Question 8

how does affirmation of consequent work

Answer 8

Antecedent (if P): cheating on me
Consequent (then Q): out of house a lot
Draw logically-invalid conclusion…
Cheating on me
…by affirming consequent…
Out of house a lot
…based on statement of fact/observation
Out of house a lot

Question 9

why is affirmation of consequent logically invalid

Answer 9

Logically-invalid (fallacious) because:
Although one thing follows another thing (if P then Q), doesn’t mean it’s logical to infer that another thing follows one thing (if Q then P)
e.g., logically-incorrect to reason that partner being out of the house a lot means she’s cheating on me
She could be out of house for host of other reasons (e.g., work, shopping)
Hopefully!

Question 10

how does denial of antecedent work

Answer 10

Socialist’ argument:
Antecedent (if P): socialist
Consequent (then Q): in favour of welfare state
Draw logically-invalid conclusion…
Not in favour of welfare state
…by denying antecedent…
(not a) socialist
…based on statement of fact/observation
Not a socialist

Question 11

why is denial of antecedent logically invalid

Answer 11

Logically-invalid (fallacious) because:
Although first part (antecedent) of premise false (not P), it doesn’t mean that it’s logical to infer that its second part (consequent) of premise also false (not Q)
e.g., logically-incorrect to infer that because you’re not a socialist you’re not in favour of welfare state
e.g., you could be a benevolent/caring capitalist who believes that all people (regardless of income/wealth) are entitled to avail of free healthcare

Question 12

Study by Evans, Handley and Buck (1998)

how much was each type of inference endorsed by participants

Answer 12

Study by Evans, Handley and Buck (1998)
Results:
Denial of the antecedent (DA): endorsed by 59% of participants
Affirmation of the consequent (AC): endorsed by 77% of participants
Modus ponens (MP): endorsed by 98% of Ps
Modus tollens (MT): endorsed by 60% of Ps

Question 13

Why is logical reasoning worse for MT logical inference than MP inference?

Answer 13

Basically, presence of negation in information statement of MT inference
e.g., There is not a dialling tone
Harder to judge logical of arguments when they contain words such as ‘not’
Two theoretical accounts:
Mental rules
Mental models

Question 14

why is modus tollens more challenging

mental rules theory

Answer 14

more rules involved
Have to deconstruct modus ponens version of argument (‘if P then Q’) before analysing modus tollens version of argument (‘if P then not-Q’)

Question 15

what are the assumptions of mental models theory

Johnson-Laird, 1983

Answer 15

Assumptions:
Procedures for manipulating mental representations
Mind contains no ‘mental logic’ (mental rules)
Models constructed to interpret/understand premise
Errors due to failure to keep track of mental models

Question 16

what are the 3 stages of mental models theory

Johnson-Laird, 1983

Answer 16

Three stages:
Comprehension of premise (model construction)
Draw conclusion based on mental models
Search for counter-examples (alternative models where conclusion false)

Question 17

issues with mental models theory (Johnson-Laird, 1983)

Answer 17

Need to generate more models for modus tollens than modus ponens
Modus tollens:
Need to ‘flesh-out’ basic, modus ponens inference mental model (‘if P then Q’) to draw conclusion
‘Fleshing-out’: basically, generating more complex mental representation of argument
Searching for counter-examples regarding content of information statement and/or conclusion
e.g., other reasons for lack of dialling tone on phone