I scored 100% in this logic test, therefore I'm a fan of Mr. Spock.

[NAKID]

Only cause you saw us complaining about the last answer!

[somegirl]

Only cause you saw us complaining about the last answer!

Nah, I clicked on the link and took the test before I read the rest of the thread.

And I am a chemist by training.

[He Man]

Not a fair analogy in this case. You didn't DEFINE what the sun is composed of. They did in the first place, therefore, by calling it "water" at any time will still mean it is comprised of 2 H and 1 O atoms.

+1 here is more fuel to the fire.

THey said ducks bark. Its a stipulation, who cares if its really true or not.

so if i said

A) The sun always rises every morning
B) The sun rises tomorrow.

will the sun rise the day after tomorrow?

Yes, because the sun rises every morning, just like water is always h2o. In reality, the sun doesnt rise every morning. The earth just spins. :p

[Johnny OrganDonor]

Question 15.
a) Water is a molecule composed of two hydrogen atoms and one oxygen atom.
b) Every observation or examination by microscope has confirmed this.

Conclusion
Therefore we can predict that every future examination of water will reveal the same chemical composition.

It's invalid but not for the reason they gave.  Premise b) states" that every observation or examination by microscope has confirmed this."  But to conclude that every future examination will reveal the same is not supported since a different future method of examination of water, such as dipping a toe into it or mixing it with scotch, might not confirm the chemical composition.  Not all examinations will reveal the chemical composition.

[CowboyBeebop]

Question 15.
a) Water is a molecule composed of two hydrogen atoms and one oxygen atom.
b) Every observation or examination by microscope has confirmed this.

Conclusion
Therefore we can predict that every future examination of water will reveal the same chemical composition.

It's invalid but not for the reason they gave.  Premise b) states" that every observation or examination by microscope has confirmed this."  But to conclude that every future examination will reveal the same is not supported since a different future method of examination of water, such as dipping a toe into it or mixing it with scotch, might not confirm the chemical composition.  Not all examinations will reveal the chemical composition.

Good catch - that explanation does make sense. 

[Big Troubled Bear]

Who cares about results

[il d00d]

It's invalid but not for the reason they gave.  Premise b) states" that every observation or examination by microscope has confirmed this."  But to conclude that every future examination will reveal the same is not supported since a different future method of examination of water, such as dipping a toe into it or mixing it with scotch, might not confirm the chemical composition.  Not all examinations will reveal the chemical composition.

I think that is the answer they gave.  It comes down to what we define as "observation"

"However, it is possible also that there may exist a substance that looks like water, boils as water, freezes as water, nourishes plants and life as water, and yet has a different chemical composition to what we know as water."

... or feels like water when you dip your toe, or tastes like water when you mix it with scotch.

These are different observations about a substance that behaves like water.  The key was you had to infer that it was *any* possible method of observation, not "by microscope".

In a nutshell, some observations reveal that a substance behaves like water.  Only one observation reveals that water is comprised of a couple of Hs and an O.

[Jobu]

Nah, I clicked on the link and took the test before I read the rest of the thread.

And I am a chemist by training.

Being a chemist is not a logical choice.   

I tried that for a while.

[Holden]

Not a fair analogy in this case. You didn't DEFINE what the sun is composed of. They did in the first place, therefore, by calling it "water" at any time will still mean it is comprised of 2 H and 1 O atoms.

You're thinking too hard. Verily I say unto you, whosoever shall not receive this logick as a little child shall in no wise partake thereof.

[zarn02]

93%

missed the water one.

[superjohn]

Question 15.
a) Water is a molecule composed of two hydrogen atoms and one oxygen atom.
b) Every observation or examination by microscope has confirmed this.

Conclusion
Therefore we can predict that every future examination of water will reveal the same chemical composition.

It's invalid but not for the reason they gave.  Premise b) states" that every observation or examination by microscope has confirmed this."  But to conclude that every future examination will reveal the same is not supported since a different future method of examination of water, such as dipping a toe into it or mixing it with scotch, might not confirm the chemical composition.  Not all examinations will reveal the chemical composition.

But, my assertion is that the question is not saying that every future examination will have the same results. It's saying "can we predict that every examination will reveal the same chemical composition." To which we CAN make that prediction. The explanation even says, "If one defines water as a property that contains two atoms of hydrogen and one atom of oxygen only, then the argument above is valid" and the first statement clearly does this.

It doesn't matter that there COULD be some magic new substance that has all the properties of water with a different chemical composition. That possibility has been precluded by the statement that "Water is a molecule composed of two hydrogen atoms and one oxygen atom."

Now, if the question said:
A.) The water you drink is composed of two hydrogen atoms and one oxygen atom.
B.) Examination has always proven this to be true

Conclusion: Water put on plants will always have the same composition.

I could call that invalid. As it stands, the test conclusion is incorrect. The original conclusion is valid.

[cloud2blue]

I had an epiphany on the last question. The person who wrote it was thinking it terms of the etymology of the word "water" not the chemistry of the substance "water." In a sense saying that the word "water" is defined as a substance comprised of H₂0. In the future it is possible the word "water" may refer to a different substance.

The problem is their execution sucked. Instead of saying, "Water is a molecule composed . . ." they should have said, "Water is defined as a molecule . . ." Given the first statement as they wrote it the conclusion can be:
"Therefore we can predict that every future examination of [a molecule composed of two hydrogen atoms and one oxygen atom] will reveal the same chemical composition." And there in lies the flaw.

I stand by my call of SHENANIGANS

[il d00d]

But, my assertion is that the question is not saying that every future examination will have the same results. It's saying "can we predict that every examination will reveal the same chemical composition." To which we CAN make that prediction.

That's a circular argument.  The whole point of the question is microscopes are the way we can confirm the chemical makeup of water.  That is the only way.  All other ways of observing water-like behavior do not confirm the chemical makeup, but can confirm that it behaves like water.  The logical gap there is what we call water may or may not be water.  We have to look under a microscope to be sure. 

You're saying, if we can already confirm that water is made up of H20, then we can predict that it is made up of H20.  Or, because it behaves like water, it is made up of H20 - this is the logical fallacy"begging the question"

The problem is their execution sucked. Instead of saying, "Water is a molecule composed . . ." they should have said, "Water is defined as a molecule . . ." Given the first statement as they wrote it the conclusion can be:
"Therefore we can predict that every future examination of [a molecule composed of two hydrogen atoms and one oxygen atom] will reveal the same chemical composition." And there in lies the flaw.

Same as above.  If we already know its chemical makeup, we are not predicting anything.  You're saying the wording was funky, which is valid.  It is like one of those brain teasers "is there a fourth of July in England?" which is just word trickery.  But, the logic in the answer is right...

[Porsche Monkey]

If I keep reading this thread y'all are gonna give me an anurism (spelling?)

[NAKID]

They didn't say "any future examination of a water-like substance".....