L01 - Deductive Argument Flashcards
Affirming the Consequent
An invalid argument in the form ‘If P then Q (premise 1). Q (premise 2). Therefore, P (conclusion)’. This invalid form is often confused with the valid form Modus Ponens.
Antecedent
In a conditional that has the form ‘If P, then Q’ (or ‘If P, Q’), P is the antecedent.
Assertion (or Statement)
Either the act of advancing a sentence as true or the product of that act.
Conditional
A complex sentence of the form ‘If P, Q’ or ‘Q if P’. It involves two elements: P is the antecedent, and Q is the consequent.
Conjunctive Statement (Conjunction)
A complex statement consisting of two sentences (conjuncts) that are joined by a conjunction, such as ‘and’ or ‘but’.
Consequent
In a conditional that has the form ‘If P then Q’, Q is the consequent.
Constructive Dilemma
Deductively valid argument form of the following variety:
(1) P or Q
(2) If P then R
(3) If Q then S
Therefore,
(4) R or S
Disjunctive Statement (Disjunction)
A complex statement that consists in two sentences that are presented as alternatives.
Disjunctive Syllogism
Deductively valid argument form of the following variety:
(1) P or Q
(2) Not Q
Therefore,
(3) P
Hypothetical Syllogism
Deductively valid argument form of the following variety:
(1) If P then Q
(2) If Q then R
Therefore,
(3) If P then R
Modus Ponens
Deductively valid argument form of the following variety:
(1) If P, then Q
(2) P
Therefore,
(3) Q
Modus Tollens
Deductively valid argument form of the following variety:
(1) If P, then Q
(2) Not Q
Therefore
(3) Not P
Necessary Condition
A condition that must be met for a claim to be true.
Necessary Truth
A necessary truth is a claim that is true in all possible scenarios.
Soundness
For an argument to be sound is for it to be valid and for all its premises to be true. By definition, a sound argument proves its conclusion.
