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Galileo’s observations

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Galileo’s observations

by nikhilkatira » Wed Jun 23, 2010 4:33 am
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
Best,
Nikhil H. Katira
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by albatross86 » Wed Jun 23, 2010 5:12 am
Premise 1: A theory is true or false.
Premise 2: Galileo observed that Ptolemaic theory is false.
Premise 3: Copernican theory is inconsistent with Ptolemaic account
Conclusion: Copernican theory is true.

Prephrased assumption: If one theory is inconsistent with a false theory, it is true.

What is the questionable assumption?

A. This may be tempting since it seems like Galileo is being credited with disproved the theory, but this is not the case. It is only stated that his observations showed that it is false. It is also not evident that his observations were the first ones. So this choice is not an assumption that is necessary to the argument, which focuses not on who gets the credit, but on the relationship between the two theories.

B. Not true, the observations simply disproved Ptolemaic theory.

C. Even if they are based on the same evidence, they could have had different conclusions and yet be inconsistent, so it need not be assumed for this to be impossible.

D. This need not be true, perhaps a few counterexamples sufficed?

E. Exactly. Who is to say that just because Copernican theory is inconsistent with Ptolemaic, it itself cannot also be false due to other reasons? The argument thus makes the very questionable assumption that 2 inconsistent theories cannot both be false, when in fact it may be the case that they can.

Pick E.
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by diebeatsthegmat » Thu Jul 01, 2010 11:30 am
nikhilkatira wrote: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
e too
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by reply2spg » Sat Jul 24, 2010 7:33 pm
Only C and E are contenders. C is wrong because we don't know whether both theories based on the same evidence.

E for me.
nikhilkatira wrote: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
Sudhanshu
(have lot of things to learn from all of you)
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by [email protected] » Wed Jul 24, 2013 12:00 pm
Can an expert please explain why C is wrong. I am not able to understand how that relates to the question and how it is incorrect?
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by jimenezca » Wed Jul 24, 2013 1:03 pm
[email protected] wrote:Can an expert please explain why C is wrong. I am not able to understand how that relates to the question and how it is incorrect?
The question is asking: "Given the line of argumentation being drawn in the passage, which of the following statements can be said to be problematic in drawing its conclusion?" In other words, "Which of the following statements can be said to be a weak or questionable assumption being made by the line argumentation and its subsequent conclusion?"

What we are looking for is an answer choice that is being assumed by the line of argumentation. Therefore, we are dealing with an Assumption type question, except that rather than directly providing just any corresponding underlying assumption, what we are looking for is an answer choice that identifies a problematic underlying assumption. The difficulty of this question seems to be found in the need to distinguish between C as a general underlying assumption and E as a problematic underlying assumption. Both fit the general description of being underlying assumptions, but the question is asking for a very specific type, a problematic or questionable assumption underlying the argument:

C. the Ptolemaic and Copernican theories, being inconsistent, cannot both be based on exactly the same evidence. We are looking for a problematic or questionable claim, which means that the statement must be logically fallible in some way. Answer choice C actually seems to be based on sound reasoning considering that a line of evidence, such as Galileo's observations of Jupiter's satellites, cannot both support the Ptolemaic and Copernican theories because in this specific instance what we get is two diametrically (absolutely) opposed theories where evidence for one necessarily would make another impossible. Therefore, if Galileo theorizes a certain conclusion based on evidence drawn from observation, it is reasonable to assume that evidence that falls in line with a Copernican theory of the cosmos (that the earth revolves around the sun) will directly contradict a theory that is based on the opposite configuration (the Ptolemaic theory that the sun revolves around the earth). However, you do not need to know the difference between the Ptolemaic and Copernican views of the cosmos to answer the question: the statement claims that the Ptolemaic and Copernican theories are inconsistent, that is, opposed in some way. Therefore, it is reasonable to assume that evidence supporting one configuration (Copernican) will likely foreclose the viability of another theory that has directly contradictory ideas (Ptolemaic). C is therefore incorrect because we are looking for a fallible or precarious assumption whereas the current one is a reasonable assumption.

E. the Ptolemaic and Copernican theories, being inconsistent, cannot both be false. This is the only possible correct answer choice because, being only theories, they are always subject to revision and therefore can always potentially be proven false. Therefore, E presents a precarious or questionable claim that because the Ptolemaic theory is likely false then the Copernican MUST be true. It could very well be that quantum physics may reveal something entirely contrary about gravity at a later date, for example. The point is that because it is possible for Galileo to be wrong, even if he is very likely right, it is unreasonable to assume that the Copernican theory is right BECAUSE the Ptolemaic is incorrect: the assumption goes too far, making D the correct answer.

Hope this clarifies,

Albert
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