Critical Reasoning

Dear Friends,

I was having problems in answering the following question.

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


Please help.

OA after some discussions.

My choice was option C

Regards
Deano.

I will go with E

Argument conclusion is Galileo proved the truth of Copernican

Premise 1 - Theory is either true or false

Premise 2 - Galileo's observations of Jupiter's satellites showed that the
Ptolemaic theory of the motion of celestial bodies is false

Premise 3 - the Copernican
theory of planetary motion is inconsistent with the Ptolemaic account

Taking three premises, author argues that since Ptolemaic is false, Copernican should be true.

Or generalizing, if one theory is false, any inconsistent theory to that false theory will be true.

Which is given in E

Conclusion: Galileo proved Copernicus was right.

Evidence: Copernican & Ptolemaic theories are inconsistent. Galileo showed Ptolemaic was false.

Assumption: Just because P was false, means that C must be true.

Question Rephrase: What is a questionable assumption?

The big gap in logic here is why does C have to be true, just because G proved that P was false?

E is correct, because it's relying on the same flawed assumption: C cannot also be false, so it must be true.

two theories are inconsistent. E shows the correct assumption.