The logical operator that joins two propositions and is true if and only if both propositions are true.
What is a conjunction?
This is represented by a lower case letter and can represent any proposition.
What is PROPOSITIONAL VARIABLE?
Logical operator that denies or contradicts a proposition.
What is negation?
A statement.
What is a PROPOSITION?
A sentence which is either true or false
What is a statement?
What are 3 tools used in Propositional Logic?
1. Truth Tables
2. Formal Proofs
3. Truth Trees
This is a listing of the possible truth values for a set of one or more propositions.
What is a Truth Table?
What is a COMPOUND PROPOSITION?
The proposition that follows the "if" in a conditional proposition.
What is the ANTECEDENT?
This is represented by an upper case letter, and represents a single, given proposition.
What is a PROPOSITIONAL CONSTANT?
The proposition that follows the "then" in a conditional proposition.
The 3 main oppositions to escape the "horns of a dilemma"
1. Go between the horns.
2. grasp it by the horns
3. rebut the horns
This is a truth table that completely defines its operations on a minimum number of variables
What is a DEFINING TRUTH TABLE?
The logical operator that joins two propositions and is false if and only if both propositions are false.
What is a disjunction?
A proposition whose truth value depends on the truth value of its component parts.
What is a truth-functional proposition?
This is a proposition that is always true due to its logical structure
What is a tautology?
What are five statements that are equivalent to
- if p then q
- p implies q
- p only if q
- when p, q
- p is sufficient for q
Two propositions are considered THIS if and only if they have identical truth values.
What is LOGICALLY EQUIVALENT?
Valid argument forms which can be used to justify steps in a proof.
Rules of Inference
This is what we call words which combine or modify simple propositions to make compound propositions.
The steps for which are:
1. write premises in symbols and number them.
2. deduce intermediate conclusions using the rules of inference, justifying each step by writing the steps used as premises and the abbreviation for the rule.
3. continue until the desired conclusion is reached
What is the Formal Proof Method for validity?
A step-by-step deduction of a conclusion from a set of premises, each step being justified by an appropriate basic rule.
Formal Proof for Validity (tool #2)
A valid argument which presents a choice between two conditionals
What is a dilemma?
Construct a counter-dilemma using the same or similar components as the original dilemma - another way of looking at the facts in order to arrive at a different conclusion.
Rebut the Horns
What are two statements that are equivalent to
- p if q
- p is necessary for q
This is when a proposition is always false due to its logical structure.
What is self-contradiction?
In this type of argument, if the premises are true, the conclusion must be true.
What is a valid argument?
Reject at least one of the two conditionals in the conjunctive premise
Grasp the Horns
This is also called an extended, or double, Modus Ponens.
What is Constructive Dilemma
Provide a 3rd alternative (deny the disjunctive premise)
Go Between the Horns
This is called an extended, or double, Modus Tollens.
A proposition with only one component part (NO logical operators)
What is a SIMPLE PROPOSITION?
a set of propositions which CAN all be true at the same time.
consistent propositions
A branch of formal, deductive logic in which the basic unit of thought is the proposition
What is PROPOSITIONAL LOGIC?
A shorter truth table can test for these 3 relationships between propositions.
1. validity
2. consistency
3. equivalence