Logical Reasoning

PT151 · S3 · Q9 Until recently it was widely believed

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Until recently it was widely believed that only a limited number of species could reproduce through parthenogenesis, reproduction by a female alone.

Conclusion

The number of species that can reproduce through parthenogenesis must be increasing.

Evidence

We used to think that only a few species could reproduce this way, but recently we've found it in a variety of unexpected cases.

Evaluate

Just because we've found more cases of parthenogenesis doesn't mean that there are more and more new species with parthenogenesis than before. Sharks and Komodo dragons have been around for millions of years. So if they're capable of parthenogenesis, then they would have already been included in a proper tally of species that can reproduce through parthenogenesis.

When we discover more oil in some new well, we don't conclude that the Earth must have more oil than it used to.

Goal

The author is thinking "why are we discovering more cases of parthenogenesis" (curious fact) and arriving at the causal story of "parthenogenesis is increasing among species", when it's highly possible that an alternate explanation is that we're just discovering more cases of parthenogenesis that already existed, prior to our discovery.

9.

The reasoning in the argument is most vulnerable to criticism on the grounds that the argument

  1. equates mere interest in a

    Too Strong

    Too Strong: interest = understanding Out of Scope: real understanding The author never acted like interest in a subject is identical to understanding. In fact, real understanding is out of scope. And interest is only discussed in an inessential modifier that isn't part of the conclusion or evidence.

    5% picked this

  2. takes for granted that because

    Wrong Flaw

    This refers to the famous Causal flaw, which is not what this is. There is a before / after here, if we say BEFORE: thought there were only a few Partheno's AFTER: discovered some more Partheno's But the author certainly isn't saying that our earlier thinking caused our new discoveries.

    20% picked this

  3. Correct

    takes ignorance of the occurrence

    Why this is right

    This is just a creative way of them saying that the author is failing to distinguish between greater awareness that X exists and increased existence of X. If someone thinks seeing more of X = there is more X they think not seeing X = there isn't X When we discover the existence of parthenogenesis in sharks, should we think, "They've always had it, but we just noticed it" or "They haven't had it until just now"? The author is thinking the 2nd way. He thinks previously sharks did not reproduce through parthenogenesis. But now they do. That's the only way to think that shark parthenogenesis has increased the number of species capable of parthenogenesis.

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

    66% picked this

  4. overlooks a crucial difference between

    Wrong Flaw

    This sounds like an objection to a dubious Comparison. The things presented as similar were sharks and Komodo dragons (they were both recently discovered to be capable of parthenogenesis). This answer is saying that our primary objection to this argument is, "But there's an important difference between sharks and Komodo dragons ... !" We definitely weren't making that kind of objection.

    7% picked this

  5. presumes that because research is

    Too Strong: Newer = Better

    Our author isn't comparing the quality of newer research to older research, and certainly not making the extreme claim that newer guarantees better. He says that an older belief (very few do parthenogenesis) is potentially being modified in light of new discoveries (whoa, did you know sharks and Komodo dragons do parthenogenesis too?)

    2% picked this

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