Logic Forms Flashcards
(56 cards)
- If P, then Q.
- P.
Therefore, Q.
Modus Ponens
- If P, then Q.
- Not Q.
Therefore, not P.
Modus Tollens
- P or Q.
- Not P.
Therefore, Q.
Disjunctive Syllogism
- P or Q.
- If P then R.
- If Q then S.
Therefore, R or S.
Dilemma
- If P then Q.
- If Q then R.
Therefore, if P then R.
Hypothetical Syllogism
- If P then Q.
- Q
Therefore, P.
Affirming the Consequent
- If P then Q.
- Not P.
Therefore, not Q.
Denying the Antecedent
a set of reasons or evidence meant to support a proposition.
Argument
a claim, something that can be true or false.
Proposition
a proposition being supported by reasons or evidence
Conclusion
a proposition offered as a reason or evidence in support of a conclusion
Premise
An “if-then” statement.
Conditional
It is impossible for all premises to be true and the conclusion false.
When an argument is (deductively) valid
an argument meant to be deductively valid
Deductive Argument
deductive argument that is not valid, but is meant to be
Invalid Deductive Argument
An argument that is valid and has all true premises
Sound Argument
An argument that is either invalid or has at least one false premise, or both.
Unsound Argument
Failed or flawed argument that can trick or deceive.
Fallacy
a fallacy that fails because of its form - it is a misleading invalid argument.
Formal Fallacy
A proposition that is not a compound proposition.
Atomic Proposition
A proposition composed of atomic propositions and logical connectives
Compound Proposition
If… Then….
…and…
…or…
…not…
Logical Connectives
A proposition that, together with a connective, makes another proposition. (A proposition that is apart of the main proposition.)
Sub-Proposition
The connective that is not a part of a sub-proposition.
Main Connective