How do truth tables work? A logic quiz on and, or and if-then
Truth tables list every possible combination of truth values for a compound statement and show the resulting value for each possible assignment. The quiz covers conjunction, inclusive or, conditional statements, tautology and contradiction in propositional logic. Try the ten questions and see how you do.
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Question 1
What is a proposition in formal logic?
A proposition is defined as a claim that possesses a definite truth value of either true or false.
Source excerpt +
In logic, we call a statement that is either true or false a proposition.
From the Knowverse course text.
Question 2
Which sentence is a proposition in classical logic?
A false mathematical statement still has a truth value. Commands and questions do not assert propositions.
Source excerpt +
Even though that statement is mathematically wrong, it is still a proposition with a 'False' truth value.
From the Knowverse course text.
Question 3
What is the truth value of a statement that has been negated twice in formal logic?
Double negation flips a truth value twice, returning it to its original state.
Source excerpt +
In logic, two negatives always cancel each other out and return you to the original statement.
From the Knowverse course text.
Question 4
When is a conjunction using the 'And' operator considered true?
A conjunction is false if even one component is false; every statement joined by 'And' must be true.
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A conjunction acts like a strict judge who only accepts the total truth.
From the Knowverse course text.
Question 5
How does the inclusive 'Or' operator behave in logic?
Logical disjunction is inclusive, meaning it evaluates as true whenever at least one component, or both, is true.
Source excerpt +
Inclusive means that the statement works if the first part is true, the second part is true, or both are true.
From the Knowverse course text.
Question 6
In the conditional statement 'If it rains, then the ground gets wet', what role does 'it rains' play?
The antecedent is the proposition following if. The consequent follows then. A logical conditional does not by itself establish a causal mechanism.
Source excerpt +
In logic, this first part is called the antecedent. The antecedent is the 'if' portion that must be true for the rest of the statement to matter.
From the Knowverse course text.
Question 7
What is a tautology?
A tautology is a logical structure that remains true under every single potential condition.
Source excerpt +
In logic, we call a statement that is true in every possible case a tautology.
From the Knowverse course text.
Question 8
What is a contradiction in logic?
A contradiction contains opposing elements that guarantee it evaluates as false in every scenario.
Source excerpt +
A statement that is always false, no matter what, is called a contradiction.
From the Knowverse course text.
Question 9
For a universal claim over a stated domain to be true, which condition must hold?
Universal quantification applies to an entire set without exception; a single counter-example makes it false.
Source excerpt +
For a Universal Quantifier to be true, every single individual must satisfy the property being discussed.
From the Knowverse course text.
Question 10
What does a truth table display?
A truth table checks all possible truth-value combinations.
Source excerpt +
A truth table is simply a map that shows every possible combination of truth and falsity for our statements.
From the Knowverse course text.
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Classical propositional logic studies statements that have a truth value, either true or false. A false claim still qualifies. 'Ten is less than two' makes a claim with a clear truth value, while a command such as 'Close the door' asks someone to act rather than asserting something true or false.
Logical operators combine or change those truth values. Negation reverses one, and applying it twice restores the original. A conjunction, written with 'and', is true when both parts are true. An inclusive 'or' is true when at least one part is true, including when both are true.
Source excerpt +
In logic, we call a statement that is either true or false a proposition.
A truth table lists the possible combinations of truth values and the result for a compound statement. It helps distinguish a tautology, true under every assignment, from a contradiction, false under every assignment. A conditional has an antecedent after 'if' and a consequent after 'then'. Those names identify the two parts.
Quantifiers say how widely a claim applies within a stated domain. A universal claim applies to every member, so a counterexample defeats it. An existential claim needs at least one matching case. Keeping the domain clear matters when deciding which examples count and whether a claim has actually been established.
Source excerpt +
The antecedent is the 'if' portion that must be true for the rest of the statement to matter.