Mooshu is a pet. Therefore, Mooshu is a dog. If it rains, I wear a jacket. If you are in this class, then you need to take the final in the class. Premise is false.
Premise is vague or ambiguous.
The possibilities are not mutually exclusive. Some people believe God created the universe and evolution. Maybe creationism AND the current theory of evolution are BOTH wrong. A lot of research has been done on this problem, identifying the conditions under which it is easier.