Can you think logically? Take the armchair logic test! There are only 15 questions, and it doesn't take very long -if you are logical! I scored only 87%, which disappoints me. Link -via the Presurfer
(image credit: Flickr user loquenoves)
(image credit: Flickr user loquenoves)
People who score 100% must think logically.
Therefore, SyndeyClaire must think logically.
Valid or Invalid? LOL
The water one though, I think remains debatable... If it revealed a different chemical composition, i wouldn't call it water anymore. so of course every observation of water would turn out to be water.
But I didn't understand some of the questions...and I have a headache so it doesn't count. Oh.,..and the roads were slippery and took a puzzy pink pill before the quiz. ...
IT'S NOT MY FAULT!!! ;)
Yet I can't balance my checkbook or remember my phone number. What's going on!?
And @6: "There was nothing to indicate she didn’t. there is nothing illogical about saying she did it."
There is something illogical about saying she did it, because there was nothing logical that PROVED she did it. There could be a guy with gloves on still in there who killed the victim, and then took the knife and Mary and put her fingerprints on the knife and then got blood all over her. Or it could have been a robot.
I went with my gut- so if I just go with the opposite of how I feel... I will still do really bad.
Conclusion
Therefore we can predict that every future examination of water will reveal the same chemical composition.
You can predict anything you want. In fact, there's pretty good reason to make that prediction in this case. If (as the site suggests) some not-water should come along, then the prediction is wrong, but the conclusion remains valid.
Other than that, I got them all right.
Of course, I took Logic in college, so I had an unfair advantage.
I still scored 93% :D
It's not logical to only go by the information given when you are clearly in possession of further knowledge. By that I certainly disagree with the Paris one - it is not stated that we are referring to the same place. By extension, the given question is flawed insofar as it stupidly assumes simplistic logic.
... suck it dumb-dumbs.
without that clause there can be many places called Paris, one of which is stated as being in New Zealand. So without the limiting clause Jenny could actually live in Paris, Texas, or Paris, France.
In other places the quiz setter makes use of 'unstated evidence' to support a result of 'invalid', for example the murderer is supposedly not Mary because there may be other evidence. Well, if we can't include an un-stated Paris, surely we can't include an un-stated cache of evidence in our deductions.
The use of a fictional character to justify that one is ridiculous "Sherlock Holmes made his name in such cases"
Er, someone better tell the author that Sherlock Holmes is a fictional character !
@6: You're right, there's nothing (given in the facts, anyway) to indicate that she didn't do it, but the question to ask if you're looking for proof is "Given only the facts presented, is it possible, no matter how remotely or implausibly, that she did not do it?" If there's a 0.00000000001% possibility that she didn't do it, then it's not logically "proven." (The O.J. Simpson murder trial is a good example.)
All of these questions can be evaluated to come to a conclusion of both answers and still be logically assessed. For those of you that think this makes you smarter than everyone else you are sadly mistaken and are the ones that are deluded and controlled the most.
Too many factored in their own knowledge and experience to answer the questions, and failed to focus on just the situation as presented before them, therefore missing the logic.
The problem here is the difference between deductive and inductive logic. The first 14 questions were all deductive. Deductive reasoning means "if all the statements are true, the conclusion has to be true." Inductive reasoning means, "if all the statements are true, the conclusion is probably true based on previous experience."
Side note: science is utterly based on the latter, because it is an empirical system (meaning it relies on observations).
Anyway, while we say deductive reasoning is valid or invalid, we say that inductive reasoning is strong (high likelihood of correctness) or weak (low likelihood of correctness). The argument about water is strong. Any reasonable person is going to say that, if we have to say "valid" or "invalid" we should say "valid" about the water argument. However, given the explanation of why we are wrong, the website is clearly relying on the technical difference between deductive and inductive that a lay person couldn't possibly know.
Many people have trouble screening off their existing knowledge like this, which is one reason why jury verdicts aren't always sensible. Though to be fair, juries are the least worst system readily available.
As I said above - it's this kind of misunderstanding that leads to flaws in the jury system. Even with a careful explanation by a good defense lawyer you'll find many people think as you do that she's guilty.
If the question had said Splongegorblebrat instead of Paris you wouldn't have got caught. It's because you know that Paris is the name of a place. It might equally have been referring to a product or a person or anything else called Paris. Because it didn't /explicitly/ say that there are more than one entities called Paris is exactly why you assume that there is only one.
For instance:
All Cows are Ducks.
All Ducks are made from Peanut Butter.
Therefore, All Cows are made from Peanut Butter.
That is a logical syllogism. Whether or not it agrees with reality is besides the point.
Lew
If the statement had read: "Therefore every future examination of water will reveal the same chemical composition.", that would have been invalid.
A very subtle but drastic difference.
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*Answer 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.
Invalid. Invalid but controversial in philosophical circles. 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. 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. There is nothing that could logically prevent this possibility occurring so the argument then becomes invalid.
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This question is wrong. What you are asking is this:
a) Water is defined as a substance made from 2 H's and one O.
b) Every past examination of water has confirmed it to be made of molecules consisting of 2 H's and one O.
If you are given a known sample of water and asked to test it, will your observations always confirm that you are in the presence of a substance made from 2 H's and one O?
That's not true actually. I understand how logic questions work but don't accept them as logical. I would still argue the same had it been Splongegorblebrat as it is not implicit enough in the question. It is illogical to assume that there is only one Splongegorblebrat/Paris when that has not been defined.
xtivo, the murder one is invalid because while you have a number of facts, facts which together would probably be accepted in a court of law as beyond a reasonable doubt, it does not logically follow that it is true. It's a logic test, and I had to remind myself of that when I read the question.
That was the only one I missed.
As for the murder one, I just figured he could have committed suicide or fell on the knife. Mary then tried to save him, and got her fingerprints on the weapon and her DNA on the body. However, maybe I went beyond the scope of the question...
These are classic logic puzzles, so don't think about what makes intuitive sense or what the answer SHOULD be.
Only consider what conclusions you can make based on the facts you are given.
As for the water one, in reality scientists would contend that the observed molecule is not water.
But in a broader, logical sense. The question said that that
"we can predict that every future examination of water will reveal the same chemical composition"
very careful wording:
the future examination of the substance which some are claiming would not be water is water by definition in the question ("examination of water")
Since the thing examined is water by definition then it having a different molecular composition would require a broader definition of water.
Tricky, but not unfair. You have to look at the wording closely.
Good Test... I would have missed a couple if I hadn't read the questions twice.
Misread 'should' as 'could' on the horse question. The murder and water questions are intuitive if you know that they are distinguishing induction from deduction.
the biggest problem in the confusion of "logical" and "rational" stems from the so called logical one himself, Spock. He thought rationally, not logically, even though he was telling everyone the conclusions he came up with were logical
:)
The water one, general science rules dictate that theories aren't 100% true because there may be situations in which it is proven false..you can only support a theory 100% but you can't really prove it 100%.
For some questions simple Venn diagrams worked. For the rest situational logic comes in handy, just think like a lawyer/devil's advocate.
They also don't do a decent enough job of explaining why the water one is invalid, which it is. First off, the language is convoluted, so it doesn't create a syllogism as-written. In fact, a perfectly reasonable syllogistic translation of it would read:
All water molecules have 2 H, 1 O
Some water molecules have 2 H, 1 O*
Therefore, all water molecules have 2 H, 1 O
This is an example of a logical fallacy called "begging the question," in which the conclusion is assumed or stated in one of the premises.
Furthermore, particularly since Hume, deductive logic has typically not been used to make predictive statements. Essentially, the argument in this question says "So far, things have been this way, therefore things will always be this way." That's not a conclusion deductive logic can really come to, at least not on purpose. If nothing else, the phrase "we can predict" should raise a red flag, because it's distinctly out of place in a logical syllogism.
*Since we haven't observed every single water molecule, we can only say that some molecules, namely those we have observed, have this composition.
"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."
If you were to ever examine WATER and find that it did not have "the same chemical composition"(i.e. "two hydrogen atoms and one oxygen atom"), then premise 'a' would be broken. Therefore it is impossible to find a different chemical composition because it is impossible to break a premise.
The reasoning given on the answer page doesn't make any sense for this conclusion. The existence of a substance with identical properties to water, but with different chemical composition, doesn't change the fact that is was WATER that was examined and this other substance.
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I also believe the Paris question could be misleading because it in no ways states that the Paris from premise 'b' is the same Paris as in premise 'a'(there could be multiple locations named Paris or perhaps a premise refers to a individual named Paris).
Even tho' I took the same logic course many of you have taken it has been a loooooong time since then. (Good to know that not all of my brain cells were killed off in the 'shroom wars of '86.)
A is B.
Some A is B (irrelevant step)
Therefore we predict A is B.
How is that invalid?
plus i'm a chem major and i know that water is not always h20 but h30 and oh molecules as well, though still considered water. variants exist. observation, if not proven fact, provides no evidence of future perfect.
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 provides that there is a high probability that it will consist only of h20, but not that it is a veritable guarantee
and i retract the previous statement, h30 and oh mean nothing to this question
Going on their explaination, if we found a substance that appeared to be water in all ways but had a different chemical composition, it wouldn't be water.
The question is:
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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.
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They are basically saying that:
water = H2O
In the past, we have observered this
therfore,
in the future observation, water = H20.
that's valid. step b just seems like unimportant info.
They claim that "we could look at water in the future and it might have a different chemical compostion", but then we wouldn't be looking at water. They claim this would be only true if we DEFINE water as such, but his #1 statement does just that!
I believe people who got 93% and people who got 100% should consider their scored swapped.
I got 93%, answering the Paris question as invalid. The question did not say where the Paris was that Jenny lived in, only that she lived in Paris. It then said there is a Paris in New Zealand. Therefore my answer, invalid, was valid.
I think the water question may have been a suboptimal example of proving a negative versus proving a positive.
Let's say we know that aliens exist. I claim that all aliens are green. To conclusively prove that all aliens are green, I would have to gather every single alien in the universe and show that each is green. That's really hard. How do I KNOW for sure that I have found every single alien? It's really hard to prove a positive.
On the other hand, I claim that not every alien is green. To prove that, I would only need to find one alien that isn't green. It's much easier to prove a negative.
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So maybe this is what they were getting at with the water question. To prove that all water molecules have one oxygen atom and two hydrogen atoms, you would have to example every individual water molecule in existence -- "a lot" or "all but one" does not count as "ALL."
The water one is kind of like the black swan question, which is like this
- a swan is observed to have white feathers
- all observations so far confirm that all swans have white feathers
People in middle age Europe actually believed that ALL swans are white, until someone noticed that there's a black swan outside of Europe.
It's also the title of the book on the economic collapse by Nassim Taleb.
If it said
a) Jenny lives in Paris.
b) There is a Paris in New Zealand.
c) There is a Paris in France
d) There is a Paris in Vermont
Conclusion
Therefore Jenny lives in New Zealand.
Then it would be incorrect. However all we know is:
a) Jenny lives in Paris.
b) Paris is in New Zealand.
Conclusion
Therefore Jenny lives in New Zealand.
Interesting test
Also, given the facts about the murder, I thought it would be logical to assume that the chick committed it. Even though I suspected it was wrong when I answered it.
Of course it's wrong to assume that she's the murderer but given the incriminating evidences logic implies that she did commit the murder... and this was a logic test.
Question number 12 was my only fault in this test.
NB: All men are from mars and all women are from venus... when you look at the answer and explination they talk about a book... what book are they refering to?
But this isn't 'logic' so much as a simple p->q test. Modus Tollens and what have you. There's a lot more to logic, including logical fallacies, which is what I was expecting.
And to the water-question-complainers: It's your logic that's flawed, really. Sorry. :P
there is a vital difference between "therefore we can predict that every future examination will reveal etc." and "therefore every future examination will reveal etc." (the latter being what the revealed answer addresses)
the question in fact asks whether prediction is possible. now there is nothing to stop us predicting anything about anything. but there is nothing in conditions A) and B) which leads to the logical conclusion that this should be so.
therefore the logical answer is that the statement is invalid
Dear Duke
OK take 100%
I receive more emails concerning this question than all the others together.
The answer given on the web site is, as you say, incorrect and needs adjusting, but then it would not be controversial and I would probably not get any feedback.
The syllogism itself is invalid and can only be considered as a strong inductive argument and not deductive. It is the 'we can predict' part of the conclusion which comes from nowhere, so the argument is not strictly formal. Not everyone agrees with this so I will leave you to draw your own conclusions. I discuss these points in my book if I may put in a plug!
However, just as an aside there are other types of water. Heavy water for example is water in which the hydrogen is replaced by its heavier isotope, deuteruim (D2O). It is chemically almost identical to normal water but looks, feels and tastes exactly the same. But don't drink it. This says nothing about the validity but only about the truth of the conclusion.
Thanks again for the feedback and comments,
Colin Beckley