The cause of the wreck of the ship Edmund in a severe storm

Premise 1: Vessel found with the hull in two pieces lying close together...
Premise 2: The storm's violent waves would cause pieces to drift apart if separated...

Gap/Assumption: Found connected --> Hull were connected before sinking

Conclusion: The breakup of the hull is ruled out as the cause of sinking

A. The issue is whether the sinking was caused by the breakup of the hull. OUT!
B. If underwater currents connected the hull, then breakup ocurred before sinking. This doesn't rule out the breakup of the hull. BINGO!
C. Sinking speed is not the issue. The issue is whether the breakup of the hull is a suspect. OUT!
D. Seems like the ship might have sunk before breaking up... The strength of the storm doesn't affect the issue of whether to rule out the breakup of the hull as a cause.


Answer: B

We need to keep the conclusion in perspective and then look out for assumption-

Conclusion- the breakup of the hulls did not cause the ship to sink
Premise- 2 pieces found together. He adds telling storms would have taken the 2 pieces far away
Assumption (prethinking) - maybe since the pieces are together it is not the reason for the ship sinking

Ans choice-
?

A. Ships as large as the Edmund rarely sink except in the most violent weather. Ok we want info that relates to the 2 pieces of hull. we can put this could be true category.
B. Underwater currents at the time of the storm did not move the separated pieces of the hull together again. hmmm.. looks good. PARK
C. Pieces of the hull would have sunk more quickly than the intact hull would have. we are worried about ship sinking here
D. The waves of the storm were not violent enough to have caused the ship to break up the surface. Could be true. again
E. If the ship broke up before sinking, the pieces of the hull would not have remained on the surface for very long Irrelavent. Uses a few words from the arguement to confuse us

The option B is a 'defender' type assumption which defends the assumption telling 'there is no other cause for the hull being together'

This is a very good question..took me almost 2 minutes

The cause of the wreck of the ship Edmund Fitzgerald in a severe storm on Lake Superior is still unknown. When the sunken wreckage of the vessel was found, searchers discovered the hull in two pieces lying close together. The storm’s violent waves would have caused separate pieces floating even briefly on the surface to drift apart. Therefore the breakup of the hull can be ruled out as the cause of the sinking.

Which of the following is an assumption on which the argument depends?

The argument is about the wreckage of a ship. The cause of the wreck is unknown, but the author tries to hypothesize about what could have caused this disaster. The hull was found in 2 pieces lying close together. The entire argument builds on this premise by stating that the waves would have caused the pieces to drift apart. It jumps to the conclusion that the breakup of the hull cannot be the cause of the sinking, courtesy the premise stated before.

A. Ships as large as the Edmund rarely sink except in the most violent weather. - Out of scope as it tries to establish some relationship between Edmund and the others.
B. Underwater currents at the time of the storm did not move the separated pieces of the hull together again. - Correct. Even if the waves made the pieces drift apart, the underwater currents could have made the 2 pieces come closer to each other. The author implicitly accepts that such a scenario is not possible.
C. Pieces of the hull would have sunk more quickly than the intact hull would have. - Wrong. The argument is about the pieces being close to each other and not about the rate of sinking.
D. The waves of the storm were not violent enough to have caused the ship to break up the surface. - Wrong. This merely states that the ship did not sink due to breaking. But nothing is mentioned about the hull or any other premise specific parameter.
E. If the ship broke up before sinking, the pieces of the hull would not have remained on the surface for very long. - Wrong. This is restating what we already know. The pieces of the hull were found in sunken wreckage. This means that they did not remain on the surface for long.

i understand ans B but doubt is with E. if the pieces of the hull did remain on the surface for very long, then it would be separated by the violent waves. Wouldnt this destroy the conclusion.

I am confused someone please explain clearly

The passage concludes that "the breakup of the hull can be ruled out as the cause of the sinking" because "the storm’s violent waves would have caused separate pieces floating even briefly on the surface to drift apart."

From this evidence, we know that the pieces would have drifted apart if they were separated on the surface for even a very short amount of time. If the hull came apart on the surface, the pieces would separate whether they were only "briefly" on the surface and then sank, or whether they were on the surface for a longer amount of time and then sank.

The two pieces of the hull were found close together, leading the author to conclude that the pieces did not separate on the surface for even a brief length of time, and thus "the breakup of the hull can be ruled out as the cause of the sinking."

Take another look at answer (E):

This answer choice specifies that the pieces of hull would be on the surface for a "not... very long" time. As stated above, if the ship broke up before sinking, the pieces of hull would have drifted apart almost immediately.

But remember, the author concludes that breakup of the hull did NOT cause the ship to sink. So it really doesn't matter how long the pieces might have been on the surface if the hull broke up BEFORE sinking, because the entire conclusion is that the hull did NOT break up before sinking.

The argument doesn't depend on (E) to be valid, so choice (E) is out.

I hope this helps!

Premise:
1) 2 pieces of sunken hull found close together
2) violent storm waves would cause broken pieces to immediately separate
Conclusion:
3) the ship did not sink due to the hull breaking

A. Ships as large as the Edmund rarely sink except in the most violent weather.
-- irrelevant, other ships don't matter
B. Underwater currents at the time of the storm did not move the separated pieces of the hull together again.
-- if the hull pieces moved later, then the ship might have sunk due the hull breaking, the pieces initially separated and this effect was masked by the currents, this strengthens the conclusion
C. Pieces of the hull would have sunk more quickly than the intact hull would have.
-- irrelevant, rate of sinking doesn't matter
D. The waves of the storm were not violent enough to have caused the ship to break up the surface.
-- irrelevant, we don't know what caused it to sink to begin with, maybe it wasn't the waves but that the ship hit a rocky shoal
E. If the ship broke up before sinking, the pieces of the hull would not have remained on the surface for very long.
-- actually weakens the conclusion, since then the ship could break up on the surface and then the pieces would not separate but sink down together

Note: The ship was found sunken.

The author argues that the cause of the ship sinking was not the breakup of the actual ship itself otherwise the pieces would not have been found sunken together as they were.

Possible defenders:
- eliminate alternate causes
- show that when the cause happens the effect happens

A - is besides the argument. The fact of the matter is the Ship sunk.
C - besides the fact in similar fashion. The fact of the matter is the duration of time it took for pieces to sink is besides the fact that the ship did not break up before sinking.
D - There could have been an alternate cause for the ship breaking up on the surface prior to its sinking, so this does isn't necessary for the argument to be true as the argument relates to the cause-effect relationship between breaking up and sinking.
Besides, the golden rule here for gmat questions is that "When the author makes his conclusion he believes it to be airtight, that is, he has considered and denied any other possibility".

E - If you negate this:
If the ship broke up before sinking, the pieces of the hull would have remained on the surface for very long
This wouldn't make sense and it would actually then contradict the premise and conclusion because the author's conclusion is based on the fact that "The storm’s violent waves would have caused separate pieces floating even briefly on the surface to drift apart"

B - Negate to see if it weakens the conclusion, because if it does weaken the conclusion then we can show that the authors conclusion could be arrived at via a different route.
Negated statement: Underwater currents at the time of the storm MOVED the separated pieces of the hull together again.
Now considering the premise that "The storm’s violent waves would have caused separate pieces floating even briefly on the surface to drift apart", the conclusion that " the breakup of the hull can be ruled out as the cause of the sinking" is weakened because the ship could have broken up on the surface, separated miles apart because of the violent waves, then be brought back together again underwater.

Statement B denies the possibility of this happening i.e. before we negated it " underwater currents DID NOT MOVE..." -->Therefore statement B is a defender assumption (or passive assumption).

Alternatively consider what "must be true" to arrive at the author's conclusion.
If we think a statement only could be true then it isn't required by the author to make his argument.
For example, it "could be true that underwater currents at the time did not move the separated pieces together"... NO. This statement MUST BE true otherwise, by lowering the probability of this occurring, we weaken the conclusion of the author.

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