Which of the following statements are true? For this item, use the…
2024
Which of the following statements are true?
For this item, use the introductory convention for evaluating arguments: true/false classifies propositions, whereas valid/invalid classifies arguments.
A. Propositions or statements can be true or false.
B. Propositions can be valid or invalid.
C. A valid argument must contain only true premises.
D. A valid argument must have a true conclusion.
E. In a valid argument, if its premises are true, the conclusion cannot be false.
Answer: A. A and E only — ConceptA proposition is a declarative sentence that has a truth value: true or false. In introductory argument evaluation, propositions are classified by…
- A.
A and E only
- B.
C, D and E only
- C.
D and E only
- D.
A, B, C and D only
Attempted by 3 students.
Show answer & explanation
Correct answer: A
Concept
A proposition is a declarative sentence that has a truth value: true or false.
In introductory argument evaluation, propositions are classified by truth value, while arguments are classified by validity. An argument is valid exactly when it is impossible for all its premises to be true and its conclusion false.
Application
Statement A is true: a proposition is evaluated as true or false.
Under the convention stated in the stem, statement B is false: valid and invalid classify arguments, whereas true and false classify propositions.
Statement C is false: validity does not require the premises to be actually true; it requires truth to be preserved if they are true.
Statement D is false: a valid argument may have a false conclusion when at least one premise is false.
Statement E is true: it states the defining truth-preservation condition for validity.
Cross-check and contrast
The form “All cats are reptiles; all reptiles are birds; therefore all cats are birds” is valid, although its premises and conclusion are not all true. This independently shows why C and D are not requirements of validity.
The combination C, D and E only includes C and D, which confuse validity with the actual truth of premises or conclusion.
The combination D and E only still includes D and omits A.
The combination A, B, C and D only includes B, C and D and omits E.
Result
Therefore, the true statements are A and E only.