#14 - Scientist: A controversy in paleontology centers on

[cindyhylee87]

Thanks for the explanation.

I am still not sure how to attack the stimulus when the conditional reasoning conclusion of the argument has an obvious flaw. For example, in this question, the author's conclusion is flawed (Mistaken Reversal), and you mentioned that the answer choice failed to address the flaw. What does that mean? or what does that look like when it's addressing the flaw?

Thanks again,
Cindy

[Jonathan Evans]

Hi, Cindy,

Thanks for following up!

The answer choice (D) does not address the conditional reasoning flaw because it brings in this other issue—how much dexterity the two groups have—and does not address the issue of whether it might be possible to make tools without standing upright.

That's the conditional flaw here: is it possible to make tools without standing upright?

The author assumes that you can't have free use of your hands without standing upright. This idea can be expressed symbolically as follows:

• Free use of hands Stand upright

However, this is not what the stimulus says. The premise in the stimulus states that standing upright makes free use of hands possible. This idea could be expressed symbolically as follows:

• Stand upright Free use of hands

Basically we know from the premise that standing upright makes free use of hands possible, but we don't know whether standing upright is required for free use of hands.

Answer choice (B) (the credited response) does address this flaw because it gives evidence that standing upright is not required for free use of hands. This answer choice addresses the conditional flaw by giving evidence against the author's assumption that: Free use of hands Stand upright

For strategy here, in your analysis, when dealing with conditional reasoning and flaws in conditional reasoning, try to make note of what the necessary and sufficient conditions are in the stimulus. Then note any connections that can be made between multiple conditionals, if present. For instance:

• If A, then B. If B, then C. Therefore, if A, then C.

If there is a conclusion, note whether the conclusion is valid based on the conditionals in the premise. If there is a flaw (as there is here), try to note what the problem is.

If you are asked to weaken the argument, look for a way to exploit the problem in the author's reasoning. For instance, here we show that standing upright actually isn't required for free use of hands.

If you are asked to strengthen the argument, try to address this problem in the conditional reasoning. For instance, here you might want to show that standing upright actually is required for free use of hands.

Does this help to clarify this problem? Thank you!

[Blueballoon5%]

The answer key on the powerscore student center explains that, "Answer choice (D) effectively attacks the sole premise of the stimulus..."

If this is the case, why is this answer choice wrong? If it attacks the premise, doesn't that weaken the stimulus? Moreover, what is the sole premise in the stimulus that it attacks?

Thanks!!

[James Finch]

Hi BlueBalloon,

The argument in the stimulus doesn't rest upon the manual dexterity mentioned in (D), but rather the "free use of the hands," presumably meaning that the hands were no longer on the ground being used to aid in walking, making (D) irrelevant to the argument. (B) is correct as it breaks the linkage between standing upright and advanced toolmaking, sucessfully eliminating the scientist's premise.

It could be the case that the Student Center explanation mistakenly labeled the explanation for (B) as (D), as it sounds like it was meant to explain why (B) is correct.

Hope that clears things up!

[Blueballoon5%]

thanks James Finch! I understand now!

[kwcflynn]

Hi!

Where does it say that the author assumes that you can't have free use of your hands without standing upright? I am also confused that Standing Upright is the sufficient and Free Use of Hands is the necessary when it says, "standing upright makes this possible."

THANK YOU

[Adam Tyson]

Remember, kwcflynn, that an assumption is something the author did NOT say, so looking for where they said an assumption is futile. The assumption is unstated!

Here, we know that to make advanced tools, you must have free use of the hands. We also know that if you stand up, you have free use of the hands (because standing makes that possible). The author makes an unwarranted connection between advanced toolmaking and standing up, and if we approach this argument conditionally that means he must have mistakenly reversed one of those claims. Since he is trying to prove those prehistoric human ancestors stood up first, that means he has "stand up" as a necessary condition, at least in his mind. Here's a chain that would get him there, if he mistakenly reversed the claim about standing up:

Advanced Toolmaking Free Hands Stand up

That's what this author must be thinking, even though it's backwards. Free use of the hands might be made possible some other way, like sitting down, or lying on your back. In other words, free use of the hands isn't sufficient to prove standing.

I hope that clears it up for you!

[bryceS1]

Just to understand, Answer A is only wrong because it references basic tools instead of advanced and it references Animals in general?

[Zach Foreman]

Bryce,
Correct! This is a good example of what we call "shell game". Answer choice A appears to be relevant, and if it were, it would definitely weaken. However, basic tools are not the same as advanced tools so it is not relevant. We see another example with "tool users" rather than tool makers.

[blade21cn]

I like the formal-logic way of thinking. But I get "standing upright → free use of hands" semantically. "Standing upright," by definition, means "hands are free." But the stimulus states "[A] standing upright makes this (free use of the hands) possible." Logically speaking, when A makes B possible, which one is sufficient and which one is necessary? One way to look at it, if A makes B possible, A is required, as you may need other elements to make it a reality, as it's not saying "A makes B a sure thing," or "whenever you get A, you'll always get B." Thus, B → A. However, another way to look at it, A makes B possible, that could be just one way that B can happen. There might be a C that can also make B possible. Thus, A → B. So I'm really relunctant to diagram this premise out logically.

Another question, in causal reasoning, when (CE) A → B, we know for sure A has to happen before B. But in conditional reasoning, when (SN) A → B, can we say B always happen before A as its necessary condition?

Thanks!