Next fur can find the flaw in Anoni's riddle 6 posts earlier showing that the keys are not necessarily by the table.
Yep, when I was writing it I noticed the flaws but posted it anyway to see if anyone would pick up on it xD
The flaws are
1. What trixie said
2. The phone didn't ring, that doesn't necessarily mean Billy checked his mail
3. Not checking the mail doesn't necessarily mean Billy forget the keys
Modus Tollens is a method of proof that says, for two logical statements p and q if
p -> q (p implies q)
~p (Not p)
~q (Not q)
However, this is for a p and q such that if and only if p, then q. In this case this isn't "if and only if", this is just "if" which essentially means "true in this circumstance" not "ONLY true in this circumstance".
A better question.
Assuming ONLY the first two statements (nothing else), is the third statement necessarily true? (IE: Can you prove the third statement true, only by the first two statements).
1) All knives are borks
2) Some borks are forks
3) Some knives are forks. (True or False?)