Summarize Argument: Counter-Position
The argument concludes that no birds descended from dinosaurs, counter to a common claim. This is based on the discovery that some bird fossils predate the fossils of dinosaurs from which birds were previously thought to have descended, so those birds couldn’t have descended from those dinosaurs.
Identify and Describe Flaw
The argument takes evidence proving that certain birds didn’t descend from certain dinosaurs to support a conclusion that no birds descended from any dinosaurs. However, it’s still totally possible that other birds were descended from those birdlike dinosaurs, or even that the newly discovered birds were descended from even older dinosaurs.
A
draws a generalization that is broader than is warranted by the findings cited
The argument generalizes that the entire hypothesis of birds descending from dinosaurs must not be true, based on findings that only disprove certain birds descending from certain dinosaurs.
B
rejects the consensus view of experts in the field without providing any counterevidence
The argument rejects a described consensus view of experts, but this is based on the provided counterevidence of bird fossils which predate the fossils of their claimed dinosaur ancestors.
C
attacks the adherents of the opposing view personally instead of addressing any reason for their view
The argument doesn’t make any personal attacks, and does address at least one reason for the opposing view.
D
fails to consider the possibility that dinosaurs descended from birds
The argument only attempts to counter the hypothesis that birds descended from dinosaurs. The possibility that dinosaurs descended from birds is irrelevant (and clearly absurd).
E
ignores the possibility that dinosaurs and birds descended from a common ancestor
There’s no need for the argument to consider this possibility. The argument is only concerned with countering the hypothesis that birds descended from dinosaurs, not with providing any other hypotheses about evolution.
"Surprising" Phenomenon
How can a report claiming erosion is light and a report claiming erosion is heavy both be accurate?
Objective
Any hypothesis resolving this discrepancy must state a difference between the two reports that explains how they can both be correct. This difference will not question the accuracy of either study, but will allow for erosion to be both heavy and relatively light in this region.
A
Neither report presents an extensive chemical analysis of the soil in the region.
This speaks to the reports’ methodologies without reconciling their different results. The author states that both reports are accurate, so the validity of their conclusions is not in question.
B
Both reports include computer-enhanced satellite photographs.
This speaks to the reports’ methodologies without reconciling their different results. Both reports are accurate, whether or not they include satellite photographs.
C
One report was prepared by scientists from a university, while the other report was prepared by scientists from a private consulting firm.
This refers to the people who produced the reports without addressing their findings. It does not explain how their conclusions can be simultaneously accurate.
D
One report focuses on regional topsoil erosion, while the other report focuses on riverbank erosion resulting from seasonal floods.
This explains why both reports can be accurate. They studied different types of erosion, so their results are not in conflict.
E
One report cost nearly twice as much to prepare as did the other report.
This speaks to the resources used to prepare the reports without addressing their findings. Both reports are accurate, regardless of their cost.
Summarize Argument: Counter-Position
The letter concludes that the evidence supports increasing speed limits, even though areas with lower speed limits also have lower vehicle fatality rates. This is based on the observation that fatality rates are rising in areas with lower speed limits.
Identify and Describe Flaw
The letter’s argument is flawed because it draws a conclusion about the safety of areas with low speed limits relative to other areas, while only considering evidence about areas with low speed limits. In other words, the argument fails to consider whether the same increase in fatality rates is happening in areas with higher speed limits.
A
bases its conclusion on findings from the same article that it is criticizing
The argument does base its conclusion on findings from the article which it criticizes, but this isn’t a flaw, because the argument seeks to prove that the article misinterpreted the evidence. So, it actually has to show that the same evidence leads to a different conclusion.
B
fails to consider the possibility that automobile accidents that occur at high speeds often result in fatalities
Whether high-speed accidents “often” cause fatalities isn’t relevant to the argument. The argument is specifically about the fatality rates in low-speed-limit versus high-speed-limit areas, and this possibility wouldn’t help to make that determination.
C
fails to consider the possibility that not everyone wants to drive faster
Whether or not people want to drive faster is irrelevant to the argument, because it doesn’t impact the issue of whether raising speed limits would be safer.
D
fails to consider the possibility that the vehicle-related fatality rates in other areas are also rising
The argument draws a conclusion that a higher speed limit is safer based only on evidence about rising fatality rates in low-speed-limit areas. Without knowing whether fatality rates are also rising in high-speed-limit areas, this just isn’t enough to support the conclusion.
E
does not present any claims as evidence against the opposing viewpoint
The argument does present claims as evidence against the opposing viewpoint: specifically, the increasing fatality rate in low-speed-limit areas.