When we make an argument, we must try to make one that is not only VALID, (where the premises support the conclusion), but also SOUND. A sound argument uses premises that are actually true.
This argument is both VALID and SOUND. All premises are true and the conclusion follows from the premises:
Students in Ms. Rachel's class must stay inside for lunch when it rains.
It is raining today.
Anne is in Ms. Rachel's class.
So, Anne must stay inside during lunch.
This argument is VALID but UNSOUND:
All students love math.
Tara is a student.
Therefore, Tara loves math.
Is it true that all students love math? If you love math, you might assume this is true, based on your personal experience. But it's important to remember that personal experience can be incorrect. It may not apply to other people or other situations.
So, when you analyze an argument, you need to look at both the STRUCTURE (validity) of the argument, and also the TRUTH (soundness) of the premises.
Try these two arguments:
All flowers are plants.
No plants have feathers.
Therefore, no flowers have feathers.
All books are about boy wizards.
No boy wizards are named Harry Potter.
Therefore, there are no books about Harry Potter.
They both have the same structure, they are both valid, but one is sound and the other is not.
Which argument is sound?_________________________________________________
Why? _________________________________________________________________
