Valid and invalid arguments
67. “watson, i have uncovered the following facts:
• if mrs smith is lying then moriarty has not escaped.
• either moriarty is dead or he is really jones.
• if moriarty is really jones then he has escaped.
• i am convinced mrs smith is lying.”
“good lord holmes,” replied dr watson, “what can you make of all this? ” “elementary my dear watson, moriarty is dead! ”
is holmes correct? justify your answer