* Validity: An argument is valid if its conclusion logically follows from its premises. In other words, if the premises are true, the conclusion *must* also be true.
* Soundness: An argument is sound if it is both valid and has true premises.
Therefore:
* If an argument is invalid, its conclusion does not logically follow from the premises. This means that even if the premises are true, the conclusion could still be false.
* For an argument to be sound, the conclusion must be *guaranteed* to be true by the truth of the premises. This can only happen if the argument is valid.
In summary: Soundness requires validity. If an argument is invalid, it cannot be sound, even if its premises are true.