Summarize Argument
This author concludes that Scottish druid stones are not very old. He supports this statement by saying that Irish druid stones are very old.
Identify and Describe Flaw
Our author identifies two groups of druid stones: Irish and Scottish. He tells us that all Irish stones are very old. That conditional relationship might look like this: Irish → Very Old.
Then, our author concludes that because Scottish stones are not Irish, they cannot have the characteristic of being very old (/Irish → /Very Old). The author commits the cookie-cutter flaw of confusing the necessary and sufficient conditions. All that the author has told us is that Irish druid stones are very old; he hasn’t ruled out the possibility of another type of stone also being very old. Therefore, the author’s argument is unsupported.
Then, our author concludes that because Scottish stones are not Irish, they cannot have the characteristic of being very old (/Irish → /Very Old). The author commits the cookie-cutter flaw of confusing the necessary and sufficient conditions. All that the author has told us is that Irish druid stones are very old; he hasn’t ruled out the possibility of another type of stone also being very old. Therefore, the author’s argument is unsupported.
A
allows a key term to shift in meaning from one use to the next
This is the cookie-cutter flaw of equivocation, where an author will argue a point hinged on a word that changes meaning. Our author doesn’t use terms that shift in meaning. The meaning of important terms in this argument stays consistent throughout.
B
takes the fact that most members of a group have a certain property to constitute evidence that all members of the group have that property
The author does not make a leap from most to all of a group in his argument; rather, he confuses the necessary and sufficient conditions.
C
takes for granted the very claim that it sets out to establish
This is a cookie-cutter answer choice referring to circular reasoning. For this to be the correct answer choice, our author would have had to assume or claim in his premises that Scottish druid stones are not very old. The author didn’t do that, so this is not correct.
D
presumes without justification that what was true of the members of a group in the past will continue to be true of them in the future
The author is not making predictions of the characteristics of future druid stones in their argument, but instead confusing the necessary and sufficient conditions.
E
takes the fact that all members of a group have a certain property to constitute evidence that the members of the group are the only things with that property
Our author establishes that all members of a group (the Irish druid stones) have a property (being very old), and uses this to say that something outside of the group (Scottish druid stones) cannot have that property (conclusion of Scottish stones not being very old).
Sheila: That is a bad idea. People who are driving too fast can easily lose control of their vehicles when they hit a speed bump.
Summarize Argument: Counter-Position
In response to Robert’s claim that the city of Crownsbury should install speed bumps on streets to slow down speeding drivers, Sheila concludes that this approach is a bad idea. To support her claim, Sheila points out that speeding drivers can easily lose control when hitting a speed bump.
Describe Method of Reasoning
Sheila counters the position held by Robert. She does this by showing Robert’s solution to a given problem could produce undesirable consequences.
A
raises the objection that the problem with which Robert is concerned may not be as serious as he takes it to be
Sheila does not deny the seriousness of the problem Robert is addressing. Instead, she is showing that Robert’s solution could create more problems.
B
argues that the solution Robert advocates is likely to have undesirable side effects of its own
The solution Robert advocates for is installing speed bumps on certain streets. The undesirable effect Sheila points out is speeding drivers losing control of their vehicles when driving over speed bumps.
C
defends an alternative course of action as more desirable than the one advocated by Robert
Sheila does not defend a solution different from the one Robert proposes. She only addresses Robert’s proposed solution and argues that his solution also has the potential to be dangerous.
D
concedes that the solution advocated by Robert would be effective, but insists that the reasons for this are not those given by Robert
Sheila does not concede that Robert’s solution would be effective. In fact, it is implied she thinks Robert’s solution would be ineffective if speeding drivers were to hit speed bumps.
E
charges that Robert’s proposal would have no net effect on the problem he describes
Sheila does not claim that Robert’s proposal would have no effect on the problem. In fact, she thinks Robert’s proposal would have an adverse effect on the problem.
Summarize Argument: Phenomenon-Hypothesis
Historians hypothesize that the decline in Mesopotamian wheat production was caused by too much irrigation, too little drainage, and a subsequent buildup of salt in soil. No evidence is provided.
Notable Assumptions
The historians assume that wheat production decreases when salt accumulates in the soil, while barley production isn’t affected by (or benefits from) salt accumulation.
A
The cultivation of barley requires considerably less water than does the cultivation of wheat.
The Mesopotamians didn’t seem to be running out of water. They still could’ve grown crops that required lots of water.
B
Barley has much greater resistance to the presence of salt in soil than does wheat.
Wheat couldn’t be grown in the salt-laden soil, so Mesopotamians switched to a crop that could be grown in salt-laden soil: barley.
C
Prior to 2900 B.C., barley was cultivated along with wheat, but the amount of barley produced was far less than the amount of wheat produced.
We care about how much production increased and decreased. We’re not interested in raw totals.
D
Around 2900 B.C., a series of wheat blights occurred, destroying much of the wheat crop year after year.
This actually weakens the author’s argument. Wheat production didn’t decrease because of the accumulation of salt in the soil, but rather because of the constant blights.
E
Literary and archaeological evidence indicates that in the period following 2900 B.C., barley became the principal grain in the diet of most of the inhabitants of Mesopotamia.
The historians argue about why such a change happened. We don’t care if barley virtually superseded wheat in Mesopotamian diets.