Biologist: The evolutionary advantage of sexual reproduction is that it increases the range of genetic variation in a species, which is an advantage for the species as a whole. However, an increased range of genetic variation in a species is not advantageous for any individual member of the species. It follows that the sole reason that sexual reproduction has become the rule among both animals and plants is that natural selection has favored some entire species over others.

Summarize Argument
The biologist argues that the evolutionary advantage of sexual reproduction is increasing genetic variation. But this benefit applies to the species as a whole, not to individual members. Thus, the only reason that sexual reproduction is widespread among animals and plants is because natural selection has favored entire species over others.

Identify Argument Part
This is a premise that is used to support the author’s conclusion that natural selection has favored some species over others.

A
It is a claim offered in support of the argument’s conclusion.
This is an accurate description of the claim. It directly supports the conclusion that the reason sexual reproduction is prevalent is due to natural selection favoring some species over others.
B
It is presented to raise a question that sheds doubt on the argument’s conclusion.
This statement does not cast doubt on the conclusion. It is the main premise used to support it.
C
It is a claim that the argument is designed to call into question.
The argument does not challenge this claim. The biologist believes this claim and uses it as a premise to support the conclusion
D
It describes an observed phenomenon for which the argument seeks an explanation.
The argument does not seek to explain this claim. The claim is used as support to explain the main conclusion.
E
It is presented as the main explanation of the origin of an observed phenomenon.
This statement is not the main explanation for the observed phenomenon. The “main explanation” of the phenomenon is the conclusion of the argument.

3 comments

Great question! I was tempted by (C) as well and had it selected for a hot second when I took this section.

(C) is wrong because while it's descriptively accurate, it doesn't describe the vulnerability in the reasoning. It's true that the columnist failed to specify what is meant by "innocuous everyday occurrences." But that's not why the argument is vulnerable.

This kind of wrong answer tends to be harder to spot than the descriptively inaccurate answers. But, we can see this by "fixing this mistake." Let's go ahead and "improve" the argument by specifying the what these "innocuous everyday occurrences" are.

Here's the new and "improved" argument:

Columnist: Vagrancy laws are supposed to reduce criminal activity, but they don't. Making vagrancy illegal means transforming many innocuous everyday occurrences, e.g. sleeping on the sidewalk, roaming aimlessly around the neighborhood, etc., into crimes. Thus, vagrancy laws increase crime while purporting to reduce it.

What do you think? Is the argument actually improved? Hardly. Barely. The conclusion still doesn't follow from the premises. It's still as weakly supported as before we specified what "innocuous everyday occurrences" are.

Why? (E) tells us why.

(E) could also have been written as a more "cookie cutter" flaw: shift in meaning of a key term, phrase, or concept. At the start of the argument, what do you think "reduce criminal activity" means? What kinds of "criminal activity" do you think vagrancy laws are "supposed to reduce?" Probably mostly low level crimes like drug use, petty theft or other property crimes, and okay maybe some more serious crimes. (Put aside your thoughts on the ethics of vagrancy laws, that's not the point here.) Now look at the conclusion where it says vagrancy laws "increase crime." In what sense do vagrancy laws increase crime? Do they increase drug use, theft, etc? No. It "increases crime" in a statistical, counting, classification, categorical sense. What used to be not a crime (being a vagrant) now is a crime. Okay, so "crime has increased" in the sense of reclassifying something as a crime that didn't used to be a crime. But wait, the argument was trying to disprove the claim that vagrancy laws would reduce crimes like drug use, theft, etc.

(E) could have said "allows a key concept to illicitly shift in meaning." In other words, conflating two very different ideas. Or it could have said what it in fact said "doesn't adequately distinguish between an increase in criminal activity (idea 1) and the reclassification of certain occurrences as crimes (idea 2)."

This is a terrible weakness in reasoning. We can expose this weakness more starkly with the following argument that exhibits the same:

Homicide laws are supposed to reduce criminal activity, but they in fact have the opposite effect. Last year alone, there were 239 homicides in our city, representing 20% of all serious crimes. If we had passed the legislation I introduced to strike all homicide laws from our criminal codes, there would have been 239 fewer crimes.

Yes, there would have been 239 fewer crimes. But no, crime would not have been reduced. And that's not a contradiction because the meaning of "crime" is shifting across the two sentences.


5 comments

Great question! I was tempted by (C) as well and had it selected for a hot second when I took this section.

(C) is wrong because while it's descriptively accurate, it doesn't describe the vulnerability in the reasoning. It's true that the columnist failed to specify what is meant by "innocuous everyday occurrences." But that's not why the argument is vulnerable.

This kind of wrong answer tends to be harder to spot than the descriptively inaccurate answers. But, we can see this by "fixing this mistake." Let's go ahead and "improve" the argument by specifying the what these "innocuous everyday occurrences" are.

Here's the new and "improved" argument:

Columnist: Vagrancy laws are supposed to reduce criminal activity, but they don't. Making vagrancy illegal means transforming many innocuous everyday occurrences, e.g. sleeping on the sidewalk, roaming aimlessly around the neighborhood, etc., into crimes. Thus, vagrancy laws increase crime while purporting to reduce it.

What do you think? Is the argument actually improved? Hardly. Barely. The conclusion still doesn't follow from the premises. It's still as weakly supported as before we specified what "innocuous everyday occurrences" are.

Why? (E) tells us why.

(E) could also have been written as a more "cookie cutter" flaw: shift in meaning of a key term, phrase, or concept. At the start of the argument, what do you think "reduce criminal activity" means? What kinds of "criminal activity" do you think vagrancy laws are "supposed to reduce?" Probably mostly low level crimes like drug use, petty theft or other property crimes, and okay maybe some more serious crimes. (Put aside your thoughts on the ethics of vagrancy laws, that's not the point here.) Now look at the conclusion where it says vagrancy laws "increase crime." In what sense do vagrancy laws increase crime? Do they increase drug use, theft, etc? No. It "increases crime" in a statistical, counting, classification, categorical sense. What used to be not a crime (being a vagrant) now is a crime. Okay, so "crime has increased" in the sense of reclassifying something as a crime that didn't used to be a crime. But wait, the argument was trying to disprove the claim that vagrancy laws would reduce crimes like drug use, theft, etc.

(E) could have said "allows a key concept to illicitly shift in meaning." In other words, conflating two very different ideas. Or it could have said what it in fact said "doesn't adequately distinguish between an increase in criminal activity (idea 1) and the reclassification of certain occurrences as crimes (idea 2)."

This is a terrible weakness in reasoning. We can expose this weakness more starkly with the following argument that exhibits the same:

Homicide laws are supposed to reduce criminal activity, but they in fact have the opposite effect. Last year alone, there were 239 homicides in our city, representing 20% of all serious crimes. If we had passed the legislation I introduced to strike all homicide laws from our criminal codes, there would have been 239 fewer crimes.

Yes, there would have been 239 fewer crimes. But no, crime would not have been reduced. And that's not a contradiction because the meaning of "crime" is shifting across the two sentences.


5 comments