Studied by 45 people
Confusing Sufficiency for Necessity (INVALID)
A → B
_________
B → A
A → B
_________
B → A
INVALID OR VALID?
INVALID (Confusing Sufficiency for Necessity)
Denying the Sufficient Condition (INVALID)
A → B
/A
_________
/B
A → B
/A
_________
/B
Invalid or Valid?
INVALID (Denying the Sufficient Condition)
Affirming the Necessary Condition (INVALID)
A → B
B
________
A
A → B
B
________
A
Invalid or Valid?
INVALID (Affirming the Necessary Condition)
Most Statements are NOT Reversible (INVALID)
A —m→ B
_________
B —m→ A
A —m→ B
_________
B —m→ A
Invalid or Valid?
INVALID (Most Statements are NOT Reversible)
All Before Most (INVALID)
A → B —m→ C
_________
A ←s→ C
A → B —m→ C
_________
A ←s→ C
Invalid or Valid?
INVALID (All Before Most)
All Before Some (INVALID)
A → B ←s→ C
_____________
A ←s→ C
A → B ←s→ C
_____________
A ←s→ C
Invalid or Valid?
INVALID (All Before Some)
Most Before Most (INVALID)
A —m→ B —m→ C
__________________
A ←s→ C
A —m→ B —m→ C
__________________
A ←s→ C
Invalid or Valid?
INVALID (Most before Most)
Some Before Some (INVALID)
A ←s→ B ←s→ C
______________
A ←s→ C
A ←s→ B ←s→ C
______________
A ←s→ C
Invalid or Valid?
INVALID (Some before Some)
The Conditional Argument (VALID)
A → B
(x)A
________
(x)B
A → B
(x)A
________
(x)B
Invalid or Valid?
VALID (Conditional Argument)
The Contrapositive Argument (VALID)
A → B
(x)/B
________
(x)/A
A → B
(x)/B
________
(x)/A
Invalid or Valid?
VALID (Contrapositive Argument)
Conditional Chaining (VALID)
A → B → C
________
A → C
A → B → C
________
A → C
Invalid or Valid?
VALID (Conditional Chaining)
Some Before All (VALID)
A ←s→ B → C
________
A ←s→ C
A ←s→ B → C
________
A ←s→ C
Invalid or Valid?
VALID (Some Before All)
Most Before All (VALID)
A —m→ B → C
________
A —m→ C
A —m→ B → C
________
A —m→ C
Invalid or Valid?
VALID (Most Before All)
Two Mosts (VALID)
A —m→ B
A —m→ C
________
B ←s→ C
A —m→ B
A —m→ C
________
B ←s→ C
Invalid or Valid?
VALID (Two Mosts)
Translate: “If it is hot and Brian is outside, he will be sweaty.”
H and O —> S
Negate: “If it is hot and Brian is outside, he will be sweaty.”
/S —> /H or /O
“If Brian is not sweaty, then it must be not hot or Brian must not be outside.”
Negate: A and B —> C
/C —> /A or /B
(remember that negated “and” becomes “or”)
Translate: “If Susan is feeling unwell, she will call in sick to work and stay home.”
U —> C and H
Negate: “If Susan is feeling unwell, she will call in sick to work and stay home.”
/C or /H —> /U
“If Susan doesn’t call in sick, or if she doesn’t stay home, then she is not feeling unwell.”
Negate: A —> B and C
/C or /B —> /A
(remember that negated “and” becomes “or”)
Translate: “If Talissa has a son, she will name him John or Dan.”
S —> J or D
Negate: “If Talissa has a son, she will name him John or Dan.”
/J and / D —> /S
“If Talissa doesn’t name a child John and doesn’t name a child Dan, then she didn’t have a son.”
Negate: A —> B or C
/B and /C —> /A
(remember that negated “or” becomes “and”)
Translate: “If I eat candy or rocks for breakfast, I won’t feel well.”
C or R —> /W
Negate: “If I eat candy or rocks for breakfast, I won’t feel well.”
W —> /C and /R
“If I am feeling well, then I didn’t eat candy for breakfast and I didn’t eat rocks for breakfast.”
Negate: A or B —> C
/C —> /A and /B
(remember that negated “or” becomes “and”)
“Not all” or /All
“Some not” or /Some
Note 
Flashcard (69)