I have a question about a formal fallacy, and need a thorough and authoritative response.
A = B
C = B
therefore C = A
Is this not a formal fallacy? Is it not equivalent to :
All A is B
All C is B
therefore, All C is A?
What fallacy is this?
Also,if a persons argument is as follows :
A doohickey is a thingamajiggy.
A whatchmacallit is a thingamajiggy also.
Therefore, a whatchmacallit is a doohickey.
Is this not the same as the first example? And also the second example?
How many fallacies are there in this argument?
It takes another form as well:
If a doohickey is a thingamajiggy, and a whatchmacallit is a thingamajiggy, then a whatchmacallit is a doohickey.
Or is this a case of :
A = B
C = B
therefore C = A?
Would not the valid form be :
a = b
c = b
therefore a = c?
Seems the same argument can be put in symbolic form in two ways, one valid, the other invalid, even though it is the same argument. I know an argument cannot be both valid and invalid at the same time...
Please help somebody. I'm in the middle of a debate and don't want to stick my foot in my mouth!