Explicitly identify the component statements that are part of the argument
and show the symbolic form of the argument.
Decide whether the argument is valid or invalid.
You may use truth tables, standard forms, Euler diagrams, and/or logical manipulation.
If the argument is invalid, point to its logical fallacy.
"If the fossil is an ammonite, then it is from the Crestaceous period.
If the fossil is not from the Mesozoic era, then it is not from the Crestaceous period.
If the fossil is from the Mesozoic era, then it is at least 65 million years old.
Therefore, if the fossil is an ammonite, it is at least 65 million years old."
A - fossil is an ammonite
C - the Crestaceous period
M - the mesozoic era
S - 65 million years old
Here goes nothing:
Here is one proof . . .