Truth & Validity
All milk is a liquid.
Some fluids are milk.
Therefore, some fluids are liquids.
What is the mood and figure?
AII-1
All counterexamples have a false premise.
FALSE
A term that within a statement, refers to all members of its category.
Distributed Term
Rule #1:
In at least one premise, the middle term must be...
DISTRIBUTED
A statement that can be inferred directly from another statement.
Immediate Inference
All lawsuits are civil cases.
Therefore, some lawsuits are not criminal cases, because no criminal cases are civil cases.
What is the mood and figure?
EAO-2
All counterexamples have a false conclusion.
TRUE
What term is distributed?
Some keepsakes are not mementoes.
MEMEMOTOES
Rule #2:
If a term is distributed in the... it must also be distributed in its...
CONLUSION, PREMISE
Set of all terms not included in the given term.
Complement
Example: The complement to P is Non-P
What is the schema for EIO-1?
No M is P.
Some S is M.
Therefore, some S is not P.
It is possible to develop a counterexample of a valid syllogism.
FALSE
What term is distributed?
No jayvees are delinquents.
JAYVEES, DELINQUENTS
Rule #3:
A valid syllogism cannot have two... (two words)
NEGATIVE PREMISES
A statement that reverses and negates both the subject and the predicate of the original. It is valid for A and O.
Contrapositive
What is the schema for AEE-2?
All P is M.
No S is M.
Therefore, No S is P.
No writers of lewd articles are decent citizens, but some journalists are not writers of lewd articles. Therefore, some journalists are decent citizens.
Valid or invalid?
INVALID
What is the distributed term in these abbreviated categorical statement?
1. All S is P.
2. No S is P.
3. Some S is not P.
4. Some S is P.
1. S
2. S, P
3. P
4. there isn't one
Rule #4:
A valid syllogism cannot have a... (two words)
NEGATIVE PRMISE
A statement that reverses the subject and the predicate. It is only valid for E and I statements.
Converse
The difference between truth and validity;
What is true or false?
What is valid or invalid?
Statements are true or false.
Arguments are valid or invalid.
A syllogism of the same form as the original, but with obviously true premises and an obviously false conclusion, in order to show the original to be invalid.
Counterexample
1. What statements distribute the subject?
2. What statements distribute the predicate?
1. UNIVERSAL
2. NEGATIVE
Rule #5:
A valid syllogism cannot have two... (two words) and a... (two words).
AFFIRMATIVE PRMISE, NEGATIVE CONCLUSION
A statement of the opposite quality with a negated predicate. It is valid for all statements.
Obverse