Logical Reasoning

PT127 · S1 · Q14 Over 90 percent of the human

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Over 90 percent of the human brain currently serves no purpose, as is evident from the fact that many people with significant brain damage show no discernible adverse effects.

Conclusion (So)

Once humans begin to tap into this tremendous source of creativity and innovation, many problems that today seem insurmountable will be within our ability to solve.

Intermediate Conclusion

Over 90% of the human brain currently serves no purpose.

Evidence (as is evident from the fact)

Many people with significant brain damage show no discernible adverse effects.

Evaluate

We have a three part argument structure:

Premise → Intermediate Conc → Main Conc

So we need to consider flaws occurring with each of those reasoning moves.

Given that … many people with lots of brain damage show no discernible adverse effects, Should we accept that … over 90% of the brain currently serves no purpose?

It seems like a really big leap to go from to “90% of the brain is useless”. How do we know it’s 90%, exactly?

Given that … 90% of the brain currently serves to purpose, Should we accept that … once we tap into this unused part of the brain, many currently-unsolvable problems will be solved?

The author must be assuming that this unused portion of the brain can be used and that using it would somehow expand our problem-solving capabilities.

Goal

Look for an answer complaining that the 90% figure seems to come out of nowhere, or look for an answer sounding skeptical that this “unused” part of our brain would provide us with more insight / value / brain power were we to tap into it.

14.

Which one of the following most accurately describes a flaw in the argument?

  1. The argument presumes, without providing

    Too Strong: always / easily

    This author wasn’t committed to the extreme assumption that the effects of brain damage are always easily detectable. If we negated this and said, “there are some rare cases when detecting the effects of brain damage are not easily detectable”, it wouldn’t hurt the argument in any way.

    3% picked this

  2. The argument presumes, without providing

    Too Strong: the only / any

    The author didn’t commit to the extreme position that the only reason any problem remains unsolved is a lack of creativity and innovation. The author is only assuming that “one of the reasons that some problems are currently unsolvable could be changed if we were able to tap into some of that unused brain power.

    6% picked this

  3. The argument infers that certain

    Bad Evidence Match

    When Flaw answers say the author “infers X on the basis of Y”, then the infers part should match a conclusion and the Y part should match the evidence. Did this author ever conclude that “certain parts of the brain do nothing”? Sure, she concluded that over 90% of the brain currently does nothing. Was her evidence for this the mere assertion that “we don’t know what over 90% of the brain does”? No, her evidence was that many people with bad brain damage show no discernible effects. This answer choice is describing an argument that sounds like, “We can’t figure out what over 90% of the brain does. Thus, over 90% of the brain does nothing.”

    5% picked this

  4. The argument infers that problems

    Trap

    Not Possible vs. Certain Bad Evidence Match This describes semi-famous flaw called Possible vs. Certain, because it’s saying the author made a move like, “Since some of our currently unsolvable problems will be within our ability to solve, we can conclude that these problems will get solved.” The author did infer that “problems will be solved”, but it was on the basis of the claim that “over 90% of brain currently serves no purpose”.

    5% picked this

  5. Correct

    The argument presumes, without providing

    Why this is right

    Does the author assume that the unused parts of the brain are a potential source of tremendous creativity and innovation? Sure. After all, she goes from saying that over 90% of the brain currently serves no purpose to saying “once humans begin to tap into this tremendous source of creativity and innovation”. The author never established that the unused portion of the brain is a tremendous source of creativity and innovation. She just assumes it is. If we negated this assumption, we’d be saying, “Yo, author — the unused parts of the brain are not a potential source of tremendous creativity and innovation”, which would definitely hurt the argument.

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

    81% picked this

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