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#22775
Complete Question Explanation

Must Be TrueX-SN. The correct answer choice is (B)

This stimulus gives a few conditional rules and then applies them to a specific case.

A scientific theory is a good scientific theory if it satisfies two requirements. You should realize that the relationship expressed is equivalent to “if and only if,” since IF the theory satisfies REQUIREMENTS, it is a good theory. You could have diagrammed:
  • ..... ..... ..... ..... ..... Accurately describe
    Good theory ..... :dbl: ..... ..... .....+
    ..... ..... ..... ..... ..... definite predictions
The illustration is that since Aristotle’s theory failed to make definite predictions, it was not a good theory, even though it did describe a wide range of phenomena in terms of a few elements.

You should remember that this is an EXCEPT question, so we will pick the choice that is not necessarily true.

Answer choice (A): This is inferred from the passage, and is incorrect.

Answer choice (B): This is the correct answer choice. Since the stimulus indicates that Aristotle’s theory involved describing what things are made of, it seems likely that this choice is actually false, because a description of what everything is made of does involve a wide range of physical phenomena. In any case, it might not be true, so this is a good answer to a Must Be True EXCEPT question.

Answer choice (C): Since the stimulus specifically states that Aristotle’s theory satisfies the first requirement, this answer choice is inferred, and is incorrect.

Answer choice (D): The accurate description is further defined as using only a small number of elements, so any theory using a large number of elements would fail to meet the first requirement. This choice is inferred, and is wrong.

Answer choice (E): Since the stimulus mentions that Aristotle’s theory satisfies the first requirement, we know that this choice is inferred, and is incorrect.
 ellenb
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#8953
Dear Powerscore,

I am still a bit confused as to why this stimulus is an if and only if statement.

Thanks


Ellen
 Steve Stein
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#8965
Hi Ellen,

That one is fairly unique. The author provides that a scientific theory is a good theory if it satisfies two particular requirements.

So, as long as it satisfies those requirements, it's a good theory.
(A scientific theory is a good theory if it meets those two requirements).

But let's not forget, there are two requirements for a scientific theory to be a good theory.
(A scientific theory is a good theory only if it meets those two requirements)

Putting together these two ideas:

A scientific theory is a good theory if and only if it meets those two requirements.

I hope that's helpful! Please let me know whether this is clear--thanks!

~Steve
 ellenb
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#8969
Thanks Steve, I am having trouble seeing the second part. How did you come up with it?
Thanks

Ellen
 Steve Stein
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#8980
Hi Ellen,

The word "requirements" tells us that those two things are necessary.

~Steve
 ellenb
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#9005
Now it makes sense,
so if I had:

To be a good cook you need to pass two required tests.


Will it still work to be if and only if?

Good cook<->Two Required Tests

or it has to be a noun such as requirements.

If you want to be a good you need to pass all the requirements.

Thanks

Ellen
 Nikki Siclunov
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#9019
No, in your hypothetical the relationship has only one direction:

Good cook :arrow: Pass 2 tests

The reason why in the original stimulus the relationship is bi-conditional has to do with the particular wording of the stimulus: a scientific theory is a good theory if it satisfies two particular requirements. To replicate this, you need to say:

You can be a good cook if you pass two required tests.

So, if you pass them, you're a good cook (Pass :arrow: Good Cook)
But also, the tests are required for anyone to be a good cook (Good Cook :arrow: Pass)

When you combine the two, you end up with a bi-conditional relationship:

Pass :dbl: Good Cook
 netherlands
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#9060
Hi there Ps,

I saw where Nikki was answering this question for someone else and already read through it but I also wanted to be 100% sure.

I was confused by the double arrow - but after reading what Nikki posted for someone else it looks like having the condition described by both a sufficient indicator and a necessary indicator is what created the double arrow.

So having both "if" (sufficient) and "requirements" (necessary) preceding "simple model and definite predictions" creates the double arrow (if and only if).

Is this correct?

And if so, would it be the same if a stimulus for example said:

"Every student that eats can play. Only students that eat can play" [ Students can play :dbl: Student eats ] - Basically a condition being introduced by both a sufficient and necessary condition?

Thank you!
 Jamie Caulkins
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#9067
Hey Netherlands,

It seems like you have a good grasp of the double not arrow. The example you used is correct. If you modified it to say "Any student that eats cannot play", then you would have a double not arrow, in a sense, because if a student plays, they cannot eat, and if they eat, they cannot play.

Good work!

Jamie
 ellenb
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#11914
Dear Powerscore,

So, why is answer choice B the correct answer, I read the explanations, but it made me a bit confused. I understood this way:

If Aristotel's theory passed the first requirement than the inference we can make is that it must describe a large number of observations. Thus, if it describes a large number of observations he must have made those observations in terms of the four elements he described.

Please let me know whether I understood it correctly.


Also, could you maybe please give another example of the if and only if relationship provided above or maybe how they disguise it in the tests, to the say if A than two requirement/necessary conditions, what is another type of wording they use similar to this, I just want to make sure I know the different types of wording they can use so I do not fall into their trap.


Thanks in advance!
Ellen

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