Logical Reasoning

PT146 · S1 · Q22 In 2005, an environmental group

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In 2005, an environmental group conducted a study measuring the levels of toxic chemicals in the bodies of eleven volunteers.

Conclusion (this proves that)

The regulation banning PCBs was effective in reducing human exposure to those chemicals.

Evidence

The regulation banning PCBs happened in the 1970s.

In 2005, they measured the levels of toxic chemicals in the bodies of 11 volunteers. Among the subjects tested, younger subjects showed much lower levels of PCB's.

Evaluate

The author's conclusion is offering a causal interpretation of the study's finding, so we can use our Explain Curious Fact framework.

Curious Fact ... why did the younger subjects have lower levels of PCB's in their bodies than the older subjects did?

Author's Explanation ... PCBs were banned in the 1970s --> banning PCBs effectively reduced human exposure to those chemicals --> the older subjects (who may have been alive pre-ban) had more exposure to PCBs than the younger subjects did.

As always, the flaw is that the author is far too certain of one possible explanation. ("This proves that ..")

And as always, we're supposed to remind the author that there might be other possible ways to explain that data. For example, maybe the younger subjects grew up in countries that never used PCBs. Maybe the livers of younger people are better at processing and expelling PCBs from the bloodstream.

Goal

Look for an answer complaining that the author is too sure of this one possible causal interpretation.

22.

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

  1. Correct

    takes an inconsistent stance regarding

    Why this is right

    The word "inconsistent" basically means "contradictory". To be logically inconsistent is to believe both "A" and "not A". In the context of Flaw questions, we know that one of the 10 Famous Flaws is Self-Contradiction, and the most common language used in a Self-Contradiction answer choice is "inconsistent / incompatible". We also know that this answer is almost always wrong. Almost always. We still need to be flexible and ask ourselves questions. Does the author take an inconsistent stance regarding what inferences can be drawn from the study? Does the author take any stance? Let's research. Yes, the author says in the 2nd sentence that "Scientifically valid inferences could not be draw from the study (because it's only 11 people)", but then the author goes on and draws an inference from the study. Is the author drawing what she thinks is a 'scientifically valid inference'? Yes, that's implied by the fact that she says "This proves that". This answer is thus descriptively true, and it brings up an issue worthy of criticism. "Yo, author -- why are you drawing some big, broad inference about the effects of regulation banning PCBs from this puny sample of 11 people, which you yourself acknowledge is not enough data to make such an inference?" Wow. A genuine Self-Contradiction example. It's like seeing a bald eagle in the wild.

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

    74% picked this

  2. overlooks the possibility that two

    Not an Objection

    Since this answer begins with fails to consider / overlooks the possibility, we can ask ourselves whether the idea that follows would weaken. Can we object to the author by saying, "You know ... it's possible that two or more chemicals produce the same effects"? No, that doesn't go against anything the author was thinking. Was she assuming that only one chemical can produce a certain effect? Not at all. We're talking about PCBs, which are toxic chemicals (plural). And we never hear about any of their effects.

    2% picked this

  3. concludes that a generalization has

    Not Unproven vs. Proven False

    This answer describes the famous Unproven vs. Proven False flaw. Does the author conclude that a generalization has been proven true? Sure, we could make that work, since saying "banning PCBs was effective in reducing human exposure to those chemicals" is somewhat of a general statement. And the author definitely thinks that this claim has been proven true. Is the premise the idea that "it's never been proven false that banning PCBs reduced human exposure"? No, the premise was the blood measurements of 11 volunteers.

    7% picked this

  4. takes something to be the

    Not a Coherent Objection

    This is attractive if we were looking for an answer complaining about the overly confident causal conclusion. But this doesn't end up making a plausible objection. The author takes the "ban of PCBs" to be the cause of a reduction "in human exposure to those chemicals". Can we object by saying, "Actually, author, the ban on PCB's might have been the result of a reduction in human exposure to those chemicals"? No, that's crazy talk. How would reduced exposure to PCBs cause a ban on PCBs?

    10% picked this

  5. does not consider the possibility

    Not an Objection

    Since this answer begins with fails to consider / overlooks the possibility, we can ask ourselves whether the idea that follows would weaken. Can we object to the author by saying, "You know ... it's possible that PCBs have detrimental effects for several years after exposure"? Not really. The author wasn't assuming that detrimental effects go away shortly after exposure stops. After all, PCBs were banned in the 1970s, but 30 years later in 2005, the younger subjects showed lower levels of PCBs, not no levels of PCBs. So the author definitely accepts that PCBs can stay in your system for years after exposure. The argument doesn't get into specifics about any detrimental effects.

    7% picked this

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