Question 1
An argument is unsound if and only if
◦ it is valid.
◦ it is invalid and/or it has at least one false premise.
◦ it has true premises and a true conclusion.
Question 2
An argument is valid if and only if
◦ its premises could be true and its conclusion false.
◦ it could not have all true premises and a false conclusion.
◦ it could not have all false premises and a true conclusion.