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This is another way of explaining why you can't divide by zero (which is essentially what he's doing in step 2), since it opens the door for all kinds of "proof
by dpapathanasiou 17y ago
This is another way of explaining why you can't divide by zero (which is essentially what he's doing in step 2), since it opens the door for all kinds of "proofs" that are actually fallacies.
- bad_user 17y agoHe's not dividing by zero. He's just using ... a = b -> a - b = 0 -> c * (a - b) = 0 -> c * a = c * b The whole point of the article is that implication is a binary function that doesn't have an intuitive behavior to many people. Like the following statement which evaluates to TRUE ... I have 6 legs *implies* it will rain tonight That's because the definition of the function is this ... A -> B => NOT(A) or B And this actually makes sense ... I have 6 legs *implies* I am not normal Which is true. But the reverse is false ... I am not normal, therefore I have 6 legs A -> B doesn't imply that B -> A. The equivalence function would be ... (NOT(A) and NOT(B)) or (A and B)
- dpapathanasiou 17y agoJules is right; I wasn't talking about the Levine proof, but rather the 3 step proof the blog author mentions after that. Step 2 is division by zero.
- deleted 17y ago[deleted]
- jules 17y agoI think this is what he meant: Sometimes you can extract a valid proof from this kind of bad proof by reading it in reverse: 3. 0=0 2. 1*0=0*0 1. 1=0 However, in this case the step from 2 to 1 requires "division by 0".