Logical Reasoning

PT142 · S2 · Q14 Geologists recently discovered marks

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Geologists recently discovered marks that closely resemble worm tracks in a piece of sandstone.

Conclusion

The mystery marks are probably the traces of a geological processes, not worms.

Evidence

The marks were made more than 500 million years ago, which is earlier than the earliest known traces of multicellular animal life (i.e. before we think worms could have possibly existed)

Evaluation

This is a classic Curious Fact / Explanation argument. (Curious Fact) What's up with these weird marks in this sandstone? (Author's Explanation) They're probably traces from geological processes, since they predate when worms existed

We can weaken the argument by - providing a different way to explain the marks - undermining the plausibility that the marks are from geological processes

This argument also has an Anti-Causal element to it, because it's saying that traces are not from worms. So we could also weaken this argument by somehow making the worm possibility seem more plausible.

Goal

Three possibilities: - different way to explain marks - make geological process less plausible - make worm hypothesis more plausible

14.

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

It is sometimes difficult to
Too Weak: "sometimes" / "precise"
We could boost the plausibility of the worm hypothesis by making the sandstone not sound as old as 500 million years older than the beginning of multicellular animal life. But this answer is way too weakly worded to have any impact.
3% picked this
Geological processes left a substantial
Opposite
This strengthens the argument by boosting the plausibility of the "geological processes made those marks in the sandstone" hypothesis.
1% picked this
There were some early life
No Impact
These marks were made more than 500 million years before the earliest signs of animal life, so even if these "early life forms" were some of the first signs of animal life, they are still 500 million years after the marks were made.
8% picked this
Correct
At the place where the
Why this is right
This hurts the plausibility of the "geological processes" hypothesis, since it's basically saying it wasn't possible. Only some kinds of processes could have made those marks, but those processes could not have occurred at the time the marks were made. This answer essentially refutes the author's hypothesis. It's odd to get a correct answer on Weaken that actually proves the author's conclusion is wrong, but so be it.
Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.
80% picked this
Most scientists knowledgeable about early
No Impact
Just like with (C), we don't care how early of an animal life form you were. These marks were made 500 million years prior to the earliest known animal life. It's possible that animals were around longer than we think, but 500 million years earlier than we think?! Also, this answer doesn't give us any reason to think that animal life started earlier than we currently think.
8% picked this

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