Final answer:
An argument can be valid but not sound; validity pertains to the logical structure, while soundness requires both a valid structure and true premises. A sound argument must also be valid, but a valid one may have untrue premises, making it unsound.
Step-by-step explanation:
An argument cannot be sound without being valid. A sound argument is one that is not only valid, meaning it has a logical form such that if the premises are true, the conclusion must also be true, but also has all true premises. Hence, soundness encompasses both the validity of the logical form and the truthfulness of the premises. For example, let's consider the disjunctive syllogism:
- X or Y
- Not Y
- Therefore X
No matter which true statements we replace X and Y with, if the premises are true, the conclusion will also be true, demonstrating a case of both validity and potential soundness.
However, this structure alone does not ensure the premises are true. It is important to note that an argument with false premises can still be valid, but not sound. Soundness is the stronger condition and cannot be achieved without having both true premises and a valid argument structure. Because of this interdependence, an argument that is sound must, by definition, also be valid.