Use linked chains to understand the logic and WEAKEN the argument. You WEAKEN the argument by identifying what the assumption is.

We have 3 things:
A) Galileo
B) Ptolemaic
C) Copernicus


B = False

Passage says: Since B is bad and we know that C is not the same as B, then it must be that C is true.

Why is this argument flawed?

Just because C is not the same as B -- does not mean that C cannot ALSO be False. What if BOTH (B) and (C) were false? <<--that's the assumption

Assumption = anything that says C is similar to B. Or anything that says B and C cannot both be false.

If the assumption is wrong -- if it's actually possible for both B and C to be wrong -- then the author's whole argument falls apart.

So we look through the answer choice that says something along the lines of what we mentioned above.

(E) says what we want.