#24 - No mathematical proposition can be proven true by

[snuggs]

Could someone please diagram this for me?
I think the premise goes something like:

MP ~(prove true by observation)

But I can't quite figure out how to diagram the conclusion so that the correct answer choice fits in.

Thanks,

[Steve Stein]

Hi,

Thanks for your question. The author's argument is that if a mathematical proposition can't be proven true by observation, then it can't be known to be true:

NOT able to be proven by observation NOT able to be known to be true

This argument is justified by the conditional statement provided by answer choice E, which is simply the contrapositive of the statement diagrammed above:

Able to be known true Able to be proven true by observation

I hope that's helpful! Let me know--thanks!

~Steve

[ellenb]

Dear Powerscore,

I just want to make sure I know how to diagram the stimulus for this question.
MP-->not Proven True

not possible to know-> mathematical proposition true (not sure about this one)

Then the answer E, KTT (know to be true)--->PTBT (prove to be true)

Could you please let me know how would you diagram properly the statements above.

Thanks

Ellen

[Nikki Siclunov]

Here's the breakdown of the argument:

• Premise 1: MP CANNOT be proven true by observation
  
  Conclusion: MP CANNOT be known to be True

The argument requires establishing a link between the two necessary conditions:

CANNOT be proven true by observation CANNOT be known to be true

In the contrapositive form:

Know to be true Prove true by observation

Answer choice (E) matches the contrapositive of our prephrase.

Let me know if this makes sense.

Thanks!

[ellenb]

Thanks Nikki,

For some reason I had a hard time diagramming the second statement. I switched the sufficient and the necessary conditions. I thought since the first statement came first that to be the sufficient and the MP the necessary. However, I know that order does not matter it is the logic that counts. But still I placed MP as the necessary condition. Maybe the word "any" made MP suffucient condition, or you just thought about it logically. Since, any is a sufficient condition indicator.


Also the following statement in other words is,
impossible to know to to be true = cannot be true, correct?


Thanks,

Ellen

[Nikki Siclunov]

Indeed, "any" is a sufficient condition indicator. That said, it's always an excellent idea to think about the relationship logically.

impossible to know to to be true = cannot be known true

Thanks!

[GLMDYP]

Hi Powerscore!
For this question, I chose (D). I know the "only if" there makes the remaining sentence a "necessary part", but I still think this one is better than (E). Can you please explain this question to me?
Thanks!

[David Boyle]

Hi Powerscore!
For this question, I chose (D). I know the "only if" there makes the remaining sentence a "necessary part", but I still think this one is better than (E). Can you please explain this question to me?
Thanks!

Hello,

I think D may be a sort of mistaken negation of E; it certainly sounds more convoluted than E. --E says, "kmpt arrow o", basically, that knowing requires observation. The contrapositive of this is "slash o arrow slash kmpt". Since the stimulus' first sentence could be phrased, "mpt arrow slash o", that is, "math propositions can't be proven by observation", answer E gives you the long chain, "mpt arrow slash o arrow slash kmpt", which is what you want, since "slash kmpt" is what the conclusion is, i.e., that you can't know a math proposition to be true.
D seems to say, "slash kmpt arrow slash o", which is basically a mistaken negation of E.

David

[pacer]

From the question stem, I know that the task is to find an assumption that is sufficient since the question stem reads "follows logically"

I am having trouble in diagramming the stimulus

Can I reword the first sentence as "Any mathematical proposition cannot be proven true by observation"


I prephrased that in in order for the conclusion to logically follow, we need to assume that observation is the only method of determining truth. meaning that only mathematical proposition that is proven to be true by observation can be known to be true.

But I had trouble matching my prephrase to the answer choices and/or understanding the answer choices.

My thoughts as I went through the answer choices:

A - it does not talk about observation at all
B - this weakens the argument being made
C - Seems like what I had prepharsed

proven true by observation -> known to be true

D - "only if" is a necessary indicator and sine the question stem is asking for the sufficient assumption, I eliminated this answer choice
E - "requires" is a necessary indicator so I eliminated this answer based on the same reasoning as choice D

Where am I making the mistake? Can you also clarify on how to diagram this stimulus?

Thanks

[Emily Haney-Caron]

Hi pacer,

Your pre-phrase is right on; great job!

You also did a good job eliminating A and B. C actually does not match your prephrase; C is saying that proving a proposition true by observation is SUFFICIENT, but you are looking for an answer choice that says it is NECESSARY. That's what your pre phrase is doing: it is saying that proving it true by observation is NECESSARY to knowing it is true.

That leaves us with E, which matches your pre-phrase almost exactly. E is saying the only way to know that a proposition is true is to prove it true by observation.

I hope that helps!