Help with 61-2-14 Forum

[umichan]

Can someone explain to me why C doesn't work here? I saw the reasoning as:

Premise:
1. Mark seems to be caused by worms;
2. BUT, date of the mark <<<<<< earliest known trace of MULTICELLULAR ANIMAL LIFE

Conclusion:
Mark not caused by worms, but left by geological process.

So it is basically like this:

X cannot be caused by A, because the bigger A group known dates later than X. So X might be caused by B.

What I think C is doing is offering another cause:

"No, X can also be caused by C." C here refers to EARLY LIFE FORMS, which I think distinguishes from MULTICELLULAR ANIMAL LIFE.

Grateful if anyone could let me know why I am wrong. Much appreciated!

[Christine (MLSAT)]

C here refers to EARLY LIFE FORMS, which I think distinguishes from MULTICELLULAR ANIMAL LIFE.

So, you're right that "early life forms" is not necessarily the same thing as "multicellular animal life", but don't fall into the trap of assuming that they must be different, or completely separate, groups.

We have no information about this broad category of 'early life forms' - in all likelihood some 'early life forms' were single celled, and some were multicellular. And that means that these early life forms that leave similar marks could be either, and there's nothing that directly tells us which is more likely. What we really need to assess is the likelihood that this early life form would be alive half a billion years before the earliest known multicellular life. (That's an awfully long time...)

As a sanity check, we're talking about worm tracks. If an organism is single-celled, I have a very hard time imagining how it would make something that looks like worm tracks. Tiny microscopic tracks? Sure. Something large enough to be easily mistaken for worm tracks? Seems fairly unlikely.

If these track-making early life forms are multi-celled, then they couldn't have been alive at the time the marks were made, and this information in (C) would actually strengthen the argument by eliminating another potential explanation. If they are single-celled, then it's possible they were alive at the right time, and this would weaken the argument by allowing for an alternative explanation. Even if you ignore the 'sanity check' above, if an answer would weaken one in one situation and strengthen in another, then it really does neither if the two situations are equally likely.

(Here, though, I'd argue that multi-celled is actually the far more likely scenario anyway, because of the 'sanity check' above.

What do you think?

[umichan]

Hi Christine, this really clears things up!!! I totally agree with that I should not fall into the trap of assuming that this is an absolutely different thing (and LSAT sets us up in traps like that...)

Thank you so much!

C here refers to EARLY LIFE FORMS, which I think distinguishes from MULTICELLULAR ANIMAL LIFE.

So, you're right that "early life forms" is not necessarily the same thing as "multicellular animal life", but don't fall into the trap of assuming that they must be different, or completely separate, groups.

We have no information about this broad category of 'early life forms' - in all likelihood some 'early life forms' were single celled, and some were multicellular. And that means that these early life forms that leave similar marks could be either, and there's nothing that directly tells us which is more likely. What we really need to assess is the likelihood that this early life form would be alive half a billion years before the earliest known multicellular life. (That's an awfully long time...)

As a sanity check, we're talking about worm tracks. If an organism is single-celled, I have a very hard time imagining how it would make something that looks like worm tracks. Tiny microscopic tracks? Sure. Something large enough to be easily mistaken for worm tracks? Seems fairly unlikely.

If these track-making early life forms are multi-celled, then they couldn't have been alive at the time the marks were made, and this information in (C) would actually strengthen the argument by eliminating another potential explanation. If they are single-celled, then it's possible they were alive at the right time, and this would weaken the argument by allowing for an alternative explanation. Even if you ignore the 'sanity check' above, if an answer would weaken one in one situation and strengthen in another, then it really does neither if the two situations are equally likely.

(Here, though, I'd argue that multi-celled is actually the far more likely scenario anyway, because of the 'sanity check' above.

What do you think?