Logical Reasoning

PT142 · S1 · Q23 Geologist: The dominant view that

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Geologist: The dominant view that petroleum formed from the fossilized remains of plants and animals deep in the earth's crust has been challenged by scientists who hold that it formed, not from living material, but from deep carbon deposits dating from the formation of the earth.

Conclusion

(Their theory is refuted) Petroleum didn't form from deep carbon deposits dating from the formation of the earth.

Evidence

Within petroleum are biomarkers, molecules indicating the past/present existence of a living organism.

Evaluate

Since this is rebuttal conclusion, and we're trying to Weaken, we'll basically be playing the role of the people being rebutted. We need to defend the theory that petroleum came from deep carbon deposits from back when Earth formed.

Given That (evidence) Petroleum has biomarkers in it (marks left by living organisms),

How Can We Argue (anti-conclusion) Petroleum came from deep carbon deposits from when Earth was formed?

There was no life when Earth was formed. That came way later. So if we think petroleum came from Earth formed, we need to explain how it got biomarkers in it.

Goal

Look for an answer that can explain-away the presence of biomarkers and allow us to defend the idea that petroleum came from carbon deposits that formed when Earth first started.

23.

Which one of the following, if true, most weakens the geologist's argument?

  1. Fossils have been discovered that

    Very Weak / No Impact

    This seems to have almost nothing to do with our goal (explain why petroleum that is supposedly from the time of Earth's origin would have biomarkers in it). Maybe LSAC was thinking we'd try to argue, "Hey man, if life-stuff like fossils sometimes lack biomarkers, than you shouldn't be surprised that non-life stuff like petroleum sometimes has biomarkers". But that's a very, very weak line of attack.

    27% picked this

  2. Living organisms only emerged long

    Strengthens

    This is something the author presumably is already recognizing and counting on. Since life came way after Earth's formation, the presence of life on petroleum makes it seem like petroleum didn't originate at the same time as Earth's formation.

    16% picked this

  3. It would take many millions

    No Impact

    This answer feels like it's trying to weaken the other theory, that petroleum comes from living life forms. But it doesn't weaken that theory at all. The dominant view is that petroleum came from plants and animals, like from the era of dinosaurs, which was more than 65 million years ago. So the fact that it takes millions of years for dead organisms to become petroleum is no problem for that theory.

    5% picked this

  4. Correct

    Certain strains of bacteria thrive

    Why this is right

    This allows us to defend the idea that petroleum was formed when Earth was formed, in deep deposits. oh, yeah? then why are there biomarkers on it?! Well, there are lifeforms (bacteria) deep inside the earth's crust, where the petroleum is pooled. When we suck up petroleum from the depths of the Earth's crust, we're pulling some of that bacteria up with it, hence you see biomarkers in the petroleum.

    Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

    36% picked this

  5. Some carbon deposits were formed

    Too Weak / Strengthens a Bit

    "Some" is almost always wrong on Strengthen, Weaken, and Paradox. This sounds more like it's helping the other theory, that petroleum (liquid carbon) was formed from plants and animals.

    15% picked this

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