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

【选项】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