Summarize Argument
The argument concludes that for peppered moths, which avoid predators by camouflaging themselves against trees, the darkest moths are the least likely to be spotted and eaten by predators. This is backed up with an observation that the lightest moths are the most visible against trees, so are most likely to be eaten.
Identify and Describe Flaw
The argument uses observations about the lightest moths being the most visible to support a conclusion about the darkest moths being the least visible. However, knowing which color is most visible doesn’t actually tell us which color is least visible.
For example, if trees are usually an intermediate shade between dark and light, the darkest moths may be more visible than average-colored moths.
For example, if trees are usually an intermediate shade between dark and light, the darkest moths may be more visible than average-colored moths.
A
The argument overlooks the possibility that light peppered moths had more predators than dark peppered moths.
The number of predators a moth has is irrelevant to the likelihood of a given predator noticing that moth when it tries to blend into its background, so this isn’t something the argument had to account for.
B
The argument takes for granted that peppered moths are able to control the degree to which they blend into their backgrounds.
The argument does not take this for granted—the whole point is that how different moths are colored affects their ability to blend into their backgrounds.
C
The argument presumes, without providing justification, that all peppered moths with the same coloring had the same likelihood of being seen and eaten by a predator.
The argument does not make this presumption. The entire argument is about the overall likelihood of moths being eaten based on their color, not the odds for any individual moth.
D
The argument overlooks the possibility that there were peppered moths of intermediate color that contrasted less with their backgrounds than the darkest peppered moths did.
The argument jumps straight from the lightest moths being the most visible to conclude that the darkest moths are the least visible, without considering that intermediate-colored moths might be even less visible. This means the conclusion relies on a baseless assumption.
E
The argument presumes, without providing justification, that the only defense mechanism available to peppered moths was to blend into their backgrounds.
The argument is focused on how effective the moths’ camouflage is based on color, so any other defense mechanisms they may have are irrelevant.
Historian: The standard “QWERTY” configuration of the keys on typewriters and computer keyboards was originally designed to be awkward and limit typing speed. This was because early typewriters would jam frequently if adjacent keys were struck in quick succession. Experiments have shown that keyboard configurations more efficient than QWERTY can double typing speed while tremendously reducing typing effort. However, the expense and inconvenience of switching to a new keyboard configuration prevent any configuration other than QWERTY from attaining widespread use.
Summary
The standard QWERTY style of keyboard was designed to slow down typing speed, because it was originally designed for early typewriters. These typewriters could jam if keys were typed too quickly. There exist faster keyboard configurations, but these aren’t used widely, because it would be too expensive and inconvenient to switch away from the QWERTY configuration, which people are used to.
Strongly Supported Conclusions
The original purpose of the QWERTY configuration has resulted in the standardization of a format that doesn’t allow for the fastest typing speed.
If keyboards were designed for something that didn’t jam when typing too quickly, a non-QWERTY keyboard configuration might have been used.
A
Most people who have tried typing with non-QWERTY keyboards have typed significantly more quickly using those keyboards than they usually have done using QWERTY keyboards.
Unsupported, because we only know that there are some faster configurations. There could be many others that are equally slow. And, most people might not be able to type faster even if the configuration makes it possible. They might need training and experience to type faster.
B
Early QWERTY typewriters were less likely to jam than were at least some more recent typewriters if adjacent keys were struck in quick succession.
Unsupported. We don’t have a comparison between early and later typewriters. If anything, we might suspect early typewriters were more likely to jam than later ones, assuming that technology improved in the later ones, allowing for faster typing.
C
If the designers of early typewriters had foreseen the possibility that technology would make it possible for adjacent keyboard keys to be struck in rapid succession without jamming, then they would not have proposed the QWERTY configuration.
Unsupported, because the designers of early typewriters would still be working within the limitations of the then-current technology. They still had to deal with the fact early typewriters could jam if typed too quickly.
D
The benefit to society that would result from switching to a keyboard configuration other than QWERTY is significantly greater than the overall cost of such a switch.
Unsupported, because the stimulus doesn’t give us enough to evaluate the costs and benefits of a new configuration. We know that switching would be costly and inconvenient, and we don’t know whether the benefit of faster typing would outweigh those costs.
E
If the keyboard had been designed for computers, then it would not have been designed to limit typing speed.
Strongly supported, because we know the QWERTY keyboard was designed to limit typing speed because they were designed for early typewriters. If keyboards were designed for something that did not jam when typed quickly, they probably wouldn’t have needed to limit typing speed.
Summarize Argument
The argument concludes that having a legal obligation to perform a certain action is the same as having agreed to perform that action. Why? Because agreeing to perform an action obligates someone to perform that action. From this, the argument draws the sub-conclusion that being obligated to perform an action must mean that one has agreed to perform that action.
Identify and Describe Flaw
The argument has a cookie-cutter flaw: confusing sufficient and necessary conditions. Just because an agreement to perform an action is sufficient to create an obligation to perform that action, that doesn’t mean an agreement has necessarily been made for every obligation. There might be other ways an obligation is formed.
The argument also baselessly treats “legal obligations” and “obligations” as equivalent by saying that they are “the same.”
The argument also baselessly treats “legal obligations” and “obligations” as equivalent by saying that they are “the same.”
A
The argument fails to make a crucial distinction between an action one is legally obligated to perform and an action with good consequences, and it takes for granted that everything true of legal obligations is true of obligations generally.
The argument doesn’t deal with actions with good consequences at all, so it isn’t a flaw to not distinguish them from legally obligated actions.
B
The argument takes for granted that there are obligations other than those resulting from agreements made, and it fails to consider the possibility that actions that uphold agreements made are sometimes performed for reasons other than to uphold those agreements.
The argument doesn’t take for granted that there are obligations that don’t result from agreements, or even consider that possibility. It’s also irrelevant to the argument why people make actions that uphold agreements.
C
The argument contains a premise that is logically equivalent to its conclusion, and it takes for granted that there are only certain actions that one should agree to perform.
The argument’s premise is not equivalent to its conclusion, and it doesn’t make any claims about what kinds of actions one should or shouldn’t agree to perform.
D
The argument treats a condition that is sufficient to make something an obligation as also a requirement for something to be an obligation, and it takes for granted that any obligation to perform an action is a legal obligation.
The argument treats a sufficient condition for an obligation—agreeing to perform an action—as a necessary condition, without considering that obligations can come from other sources. It also claims that legal obligations are “the same” as any other obligation to act.
E
The argument rests on an ambiguous use of the term “action,” and it fails to consider the possibility that people are sometimes unwilling to perform actions that they have agreed to perform.
The argument uses the term “action” consistently. It also doesn’t make any claims about people’s willingness to perform actions they’ve agreed to, only about their obligation to do so.
Summarize Argument
Predicting an invention is self-contradictory. Why? Because predicting an invention entails developing a detailed conception of how that invention will function. But if you manage to do that, congrats, you just invented the thing. So that’s not prediction. That’s just invention. Hence, predicting an invention is impossible.
Describe Method of Reasoning
Author argues that something (predicting an invention) is impossible because a necessary condition of that something (developing a detailed conception of how that invention will function) rules that something out by definition (you can’t predict an invention that already exists).
A
constructing a counterexample to a general hypothesis about the future
Descriptively inaccurate. Author does not construct a counterexample. There is no general hypothesis about the future to disprove.
B
appealing to definitions to infer the impossibility of a kind of occurrence
Descriptively accurate. The author implicitly appeals to the definition of “predict” (stating that something will happen) and explicitly appeals to the definition of “invent” (developing a detailed conception) to infer that a kind of occurrence (predicting an invention) is impossible.
C
countering a hypothesis by indicating the falsehood of the implications of that hypothesis
Descriptively inaccurate. We’ll grant that the “hypothesis” is that “it’s possible to predict an invention.” But the author does not demonstrate that the implications of that hypothesis are false. Rather, the author demonstrates that the hypothesis is self-contradictory.
D
pointing out how a problem is widely thought to be scientific yet is really conceptual
Descriptively inaccurate. Argument does not contain any problem that is “widely thought to be scientific” nor does the author point out any problem as being actually “conceptual.”
E
attempting to show that predicting any event implies that it has in fact already taken place
Descriptively inaccurate. Author does not attempt to show that predicting any event implies that it has in fact already taken place. That would mean prediction in general would be impossible. Author only attempts to show that predicting a specific type of event (inventions) would be impossible.
Summarize Argument
The argument concludes that there cannot be any complete theory of aesthetics. This is supported by an example of a time period in the 1960s, when beautiful new art could not be understood by the time period’s current theory of aesthetics.
Identify and Describe Flaw
The argument is flawed because it fails to consider the possibility that another theory of aesthetics could be more complete than the theory current to the 1960s. Even if one specific theory of aesthetics turns out to be incomplete, there might still be some other theory of aesthetics that can provide an understanding of all art.
A
takes for granted that it is more important for a complete aesthetic theory to account for the beauty of traditional art than for it to account for the beauty of self-consciously rebellious art
The argument doesn’t make any claims about the importance of accounting for a certain kind of beauty over another.
B
presumes, without providing justification, that artists’ rebellion in the 1960s against earlier notions of art was not guided by their knowledge of eighteenth-century European aesthetic theory
It doesn’t matter to the argument what the reason might have been for the artists’ rebellion in the 1960s.
C
presumes, without providing justification, that an aesthetic theory developed in one part of the world cannot be applied in another
The argument simply doesn’t claim that an aesthetic theory from one part of the world cannot be applied to another.
D
presumes, without providing justification, that art from the 1960s is the only art that cannot be adequately addressed by eighteenth-century European aesthetics
The argument doesn’t presume that 1960s art is the only example of art unaccounted for by eighteenth-century European aesthetic theory, but just uses it as an example to show that this aesthetic theory is incomplete.
E
presumes, without providing justification, that eighteenth-century European aesthetics is as encompassing as an aesthetic theory can be
In concluding that no aesthetic theory can be complete, the argument presumes that no aesthetic theory can be more encompassing than the incomplete eighteenth-century European aesthetic theory. This isn’t supported further, so it’s an unjustified presumption.