I have a question about the identity of a certain kind of fallacy, namely:
A = C
B = C
therefore A = C
Confusingly, I have read that the above syllogism is valid; and yet consider this argument I've heard recently:
Obama = Good speaker
Hitler = Good speaker
therefore Obama = Hitler
Clearly the latter is a fallacy.
So, I have two questions, really:
1) What is the name of this fallacy?
2) How can it be a fallacy if the first syllogism (A = C, B = C, therefore A = C), whose form it follows, is considered to be valid . . . or am I wrong about it being valid?