1. Imagine a hypothetical scenario in which you are trying to explain the concept of validity to a friend. You present the following as an example of a valid argument:

All dogs are fish

 Fido is a dog 

Fido is a fish

Your friend responds: "How can this argument be valid when it obviously just plain crazy? The conclusion as well as the premises are false. You said that if an argument is valid then it is based on good reasoning. But clearly the reasoning in this argument is horrendously bad. If this argument is valid then the concept of validity is useless. I don't need to learn anything more about it. I would rather just use common sense to evaluate arguments."

How would you explain to your friend that the reasoning at the basis of this argument is actually good and that the concept of validity is critical for the evaluation of arguments? Include your explanation a definition of validity.