galileo observations

[nik_f]

A theory is either true or false. Galileo’s observations of Jupiter’s satellites showed that
the Ptolemaic theory of the motion of celestial bodies is false. Therefore, since the
Copernican theory of planetary motion is inconsistent with the Ptolemaic account,
Galileo’s observations of Jupiter’s satellites proved the truth of the Copernican theory.
The argument above is open to the objection that it makes the questionable assumption
that
A. whoever first observed something inconsistent with the truth of the Ptolemaic
theory should be credited with having proved that theory false
B. there are some possible observations that would be inconsistent with the account
given by the Copernican theory but consistent with the account given by the
Ptolemaic theory
C. the Ptolemaic and Copernican theories, being inconsistent, cannot both be based
on exactly the same evidence
D. numerous counterexamples were necessary in order to show the Ptolemaic theory
to be false
E. the Ptolemaic and Copernican theories, being inconsistent, cannot both be false

IMO C

[sthamina]

My answer would be C. I hesitate between C and E.
This question sounds like a weaken the argument question asking to find the conclusion that could be used to arguable/weaken the conclusion.
E says both theorie have to be false for the argument to be weaken. But the text says one the theories are inconsistent.
C says we can't make a conclusion based on the same observations. And if we do, we're questioning/weakening the conclusion.

[yashesha]

difficult....

[Retake_GMAT]

IMO B, will explain if matches OA

[indy123]

E

The Ptolemaic and Copernican theories, being inconsistent, cannot both be false

(If both ptolemaic and copernican theories can be false simultaneously, then the argument that Galileo supports copernican theory just because he negates ptolemaic theory need not be true. Copernican theory can still be false)

[Praso]

agree with E

[borntorun]

IMO B

author assumes that some observations are consistent with copernicus theory and inconsistent with Plutonic theory ... so if that observation is inconsistent with plutonic (given in argument) then it is consistent with Copernicus theory ..

option E seems wrong to me ... theory can either be true of false ..so both theories can't be false ...

[nik_f]

OA is E..

[yashesha]

Jus did a little work on the above..

if CT is inconsistent with PT then CT is true..

this states that CT is sufficient condition for CT to be true....we need to find something which can challenge this.....therefore E

I feel other strong contender...is C..but E wins..

[Makumajon]

It's E. The author states that just because Ptolemaic theory is wrong, Copernican theory must be true, while in reality they both can be false. The questionable assumption is that [the author thinks] either the Ptolemaic theory or the Copernican theory must be false, but they cannot both be false.