It is a mistake to conclude, as some have, that ancient people did not know what moral rights were simply because no ...

Rinku on November 18, 2013

Strengthen with necessary premise

Could you please explain this reasoning behind this answer?

3 Replies

Melody on November 20, 2013

Here we have a Strengthen with Necessary Premise question. Remember that a premise is necessary for a conclusion if the falsity of the premise guarantees or brings about the falsity of the conclusion. First we check to see if the answer choice strengthens the passage, and then, if it does strengthen, we negate the answer choice to see if its negation makes the argument fall apart. If the answer choice does both those things then it is our correct answer.

The conclusion in the argument is: "It is a mistake to conclude, as some have, that ancient people did not know what moral rights were simply because no known ancient language has an expression correctly translatable as "a moral right." Why? Because this would be like saying "that a person who discovers a wild fruit tree and returns repeatedly to harvest from it and study it has no idea what the fruit is until naming it or leaning its name."

(A) is incorrect because it is irrelevant. Answer choice (A) is diagrammed:

KNS ==> KWI
Not KWI ==> not KNS

We know that no known ancient language has an expression correctly translatable as "a moral right." So, "not KNS." The argument claims that it is incorrect to conclude: not KNS ==> not KWI. The statement in answer choice (A) does nothing to the argument. As you can see from the necessary conditions of the principle rule and its contrapositive, KWI and not KNS can occur together. Therefore, this answer choice does not affect the passage.

(B) is incorrect because it is irrelevant. The degree to which people know something has no affect on the passage. We merely want to know whether or not ancient people knew what "a moral right" was, not to what extent they knew.

(C) is incorrect. Even though it somewhat strengthens the argument, it does not pass the second step. It strengthens by showing that the name of something provides no information about the nature of the thing that is identified. Therefore, it helps support the passage by furthering the point that just because ancient people did not have a name for "a moral right," that does not mean that they did not have information about the nature of a moral right. Now, let's negate: "The name or expression that is used to identify something can provide some information about the nature of the thing that is identified." So that means that placing a name to "a moral right" would have given ancient people SOME information about the nature of a moral right, however, it would not necessarily have given ancient people ALL the information about the nature of a moral right. Thus, there is still room for the possibility that ancient people did not have a name for "a moral right," but still knew what it was. So, answer choice (C) has not passed both tests.

(D) is CORRECT. The author uses the example about the wild fruit tree to show why those who thought ancient people didn't know what "a moral right" meant due to their lack of a word for it was ridiculous. Therefore, the wild tree example is just as wrong as the people who believe that ancient people did not know what "a moral right" meant. Thus, answer choice (D) strengthens that by showing that a person, who repeatedly harvests from a wild fruit tree and studies it, HAS SOME IDEA of what the fruit tree is before knowing a name for the fruit. Now let's negate: "A person who repeatedly harvests from a wild fruit tree and studies it has no idea of what the fruit is even before knowing a name for the fruit." This completely breaks his only evidence presented for his conclusion. He gives the wild fruit tree example to show how ridiculous it would be. However, if it were actually true that a person who repeatedly harvests from a wild fruit tree and studies it has no idea of what the fruit is even before knowing a name for the fruit, then the author has no support for his conclusion and therefore, the argument falls apart.

(E) is incorrect. It technically strengthens the argument because if one does not need to know what something is before one can name it, then just because something doesn't have a name doesn't necessarily mean that it is something unknown. However, when we negate it: "one need know what something is before one can name it," it does not make the argument fall apart. The negation means that first one must know what something is, before it CAN be named. This would be diagrammed as follows:

N ==> K
not K ==> not N

However, no name is our necessary condition here so it tells us nothing else. Therefore, there could be a period of time where one knows what something is and has yet to name it, but CAN. As such, this does not make the argument fall apart.

I hope that was helpful! Let us know if you have any other questions.

on July 23 at 08:02PM

I picked C because when I negated "The name or expression that is used to identify something can provide some information about the nature of the thing that is identified." I'm not sure I'm clear on why this doesn't break the argument?

I thought that D was too narrow, because it just discussed fruit trees (i.e. only the discussed the premise, rather than any comment on the conclusion and the relationship between the premise & conclusion)? How do I avoid making this mistake in the future?

Victoria on August 4 at 02:20PM

Hi @Anna2020,

Happy to help!

When we negate answer choice (C), it doesn't break the argument because it tells us that knowing the name of something only provides "some" information about the nature of the thing that is identified. This means that there is still more information which can be learned even without knowing the name.

Applied to the conclusion, this would mean that ancient people still knew about moral rights; they were just missing the information which would be provided by knowing the name. In this way, answer choice (C), whether negated or not, supports the author's conclusion.

On the other hand, negating answer choice (D) destroys the author's analogy, meaning that they draw their conclusion with no support.

Remember that there are two ways to attack an argument:

(1) Show that a premise is false
(2) Show that the conclusion does not logically follow, even if the premises are true

Negating answer choice (D) tells us that a person who repeatedly harvests fruit from a wild fruit tree and studies it has no idea what the fruit is before they know the name of the fruit. The author uses this analogy to demonstrate how ridiculous the mistaken claim about ancient people is; however, if the analogy is true, then it supports the mistaken claim.

A person who discovers a wild fruit tree and returns repeatedly to harvest from it and study it has no idea what the fruit is until naming it or learning its name.

Therefore, it would not be a mistake to conclude that ancient people did not know what moral rights are because they didn't have a name for them as the analogy demonstrates that one cannot know anything about something until they know its name.

Remember that the premise and the conclusion are connected, especially in a short stimulus such as this where there is only one premise supporting the conclusion. If you can demonstrate that a premise is false, the author can no longer properly draw their conclusion.

Keep up the good work and continue practicing! Please let us know if you have any further questions.