two little logic tests

[Madoness]

Few minutes to pass the time

http://www.think-logically.co.uk/lt.htmhttp://www.think-logically.co.uk/lt.htmhttp://www.think-logically.co.uk/lt.htm

Spoiler

You scored 12 (80%)

http://www.think-logically.co.uk/lt2.htm

Spoiler

You scored 14 (93%)

 

[Kuu]

Hmm that was easy, I got 15 in the first one and 14 on the second one...

 

[Minuend]

12 and 14.

 

[5k17]

Hmm that was easy, I got 15 in the first one and 14 on the second one...

Ditto.

 

[Pythia]

14 in both.

 

[Kokoro]

14 for both. I missed both of those questions because I read over them too fast and missed a key word. Just shows what can happen when one gets in a hurry with such things. (Wanting to hurry up and finish jury duty, as an example.)

 

[Enne]

15/12

 

[ckm]

15/12

Same.

 

[citrusbreath95]

14 for both

 

[nexion]

12. Second, only 11. lol

That time travel one got me. Mind you, I never thought about going to the future rather than the past, but oh well. It got me thinking of time travel again. Oh God, the mind-bending paradoxes it would create. Good thing it isn't possible.

 

[Xanstrollinoax]

First one I got 13, and 10 on the second....dang murder ones got me both times heh.

 

[asdfasdfasdfsdf]

first i got 15, second got 14.
anyone care to thoroughly explain answer 3 on part 2?
i feel like the situation given in itself is unfair and you cannot justly establish either valid or invalid

 

[nexion]

first i got 15, second got 14.
anyone care to thoroughly explain answer 3 on part 2?
i feel like the situation given in itself is unfair and you cannot justly establish either valid or invalid

I was confused on that one too. Especially since other questions with untrue premises could be marked as valid.

 

[Oblivious]

14/11

I am so ashamed of myself. I blame the army. Anyways, regarding question 3...

Only open if you've done the test already.

Spoiler

Answer 3.
a) Both premises in this syllogism are untrue.
b) Words constitute all the content of any premise.
- Therefore the words in this syllogism are all false.

The question should first be evaluated statement by statement.

First off, it is impossible to decide whether or not a) is true or false, therefore it would be incorrect to make a statement suggesting it to be either.

"This statement is untrue." Which would make it true? However, it is clearly stated to be untrue. This is what they mean by paradox. This should be enough to invalidate the conclusion since it clearly states 'words' to be false, while it should be impossible to determine.

The secondary consideration is whether or not the concept of 'words' can be 'false'. The concept of 'false' is only meaningful when applied in the context of a logical statement. A 'word' alone is not enough to form a logical statement, and therefore should not philosophically be possible to be 'false'.

 

[DarkGreen]

The tests are ridiculous. We're all intuitive aren't we? So why did some people put Gary thinks about sex all the time because he's a man? Adults have a different type of silliness, did no one read the Phantom Tollbooth when the main character pointed out to the numbers that the mathematical answers to their problems were right but the problems themselves were wrong? If Logic is not Truth then wtf do we use it for? Tell me, is Logic or Truth better in your opinions?

 

[nexion]

Of course the premises are false. But the point of these exercises were to determine if the argument is logical or not. Whether or not the premise is wrong, the argument is still logical. It forces one to look at things objectively.

 

[DarkGreen]

I can see the point of the excercises a little more clearly now thanks. Also, did you take the tests to learn or did you want to see yourself get good marks?

 

[nexion]

I can see the point of the excercises a little more clearly now thanks. Also, did you take the tests to learn or did you want to see yourself get good marks?

Haha I took the test because I was bored at about 1.30 in the morning. But it did quickly become apparent to me that in these tests, pure logic is more important than the truth displayed. Perhaps there are some situations like that in real life?

 

[DarkGreen]

Yeah, I guess Gary could be thinking about sex all the time in the real world but when it said that all men thought about sex all the time it got me angry. I have guy friends who are more than just lechers. Also, whoever said that in real life, wouldn't make alot of friends. I WOULD NOT BE HIS/HER FRIEND EVER.

 

[nexion]

Yeah, I guess Gary could be thinking about sex all the time in the real world but when it said that all men thought about sex all the time it got me angry. I have guy friends who are more than just lechers. Also, whoever said that in real life, wouldn't make alot of friends. I WOULD NOT BE HIS/HER FRIEND EVER.

Hahahaha you realize that was only a hypothetical situation right? I doubt anyone believes men think only about sex. Anyone who may have said that was probably only speaking in hyperbole.

 

[DarkGreen]

>M< it was mean. that's the reason i didn't like those tests really.

 

[asdfasdfasdfsdf]

14/11

I am so ashamed of myself. I blame the army. Anyways, regarding question 3...

Only open if you've done the test already.

Spoiler

Answer 3.
a) Both premises in this syllogism are untrue.
b) Words constitute all the content of any premise.
- Therefore the words in this syllogism are all false.

The question should first be evaluated statement by statement.

First off, it is impossible to decide whether or not a) is true or false, therefore it would be incorrect to make a statement suggesting it to be either.

"This statement is untrue." Which would make it true? However, it is clearly stated to be untrue. This is what they mean by paradox. This should be enough to invalidate the conclusion since it clearly states 'words' to be false, while it should be impossible to determine.

The secondary consideration is whether or not the concept of 'words' can be 'false'. The concept of 'false' is only meaningful when applied in the context of a logical statement. A 'word' alone is not enough to form a logical statement, and therefore should not philosophically be possible to be 'false'.

Spoiler

well the test was in such format, that you were to assume that the presumptions were true, no matter how ridiculous.
i got caught on the paradox and just guessed, but i dont think it was a fair presumption to throw.
as for the words part, while a certain individual word cannot be false, i wouldnt think, it used "words" and a group of words can from a meaning, and the group of words would be a false statement. idk. i was just totally thrown off by the fact that the test was contradicting in nature, by, in the instructions saying "you must assume these are true" and then throwing something at us that cannot be true.

EDIT:

Spoiler

idk if it was the implied reason for the answer, but if you are to presume the first 2 are correct, no matter how ridiculous, this should have been an easy freebee. for question 3, the first 2 parts are just random claims that you are to assume are true, and the statement questioning the validity is saying "these presumptions are false" im not sure if it was the intended reasoning, but if you are to automatically assume the presumptions are true, and the statement is saying "the presumptions are false" then, by the instructions, the statement is invalid.
meh. i can relax on this now.

 

[nexion]

Spoiler

well the test was in such format, that you were to assume that the presumptions were true, no matter how ridiculous.
i got caught on the paradox and just guessed, but i dont think it was a fair presumption to throw.
as for the words part, while a certain individual word cannot be false, i wouldnt think, it used "words" and a group of words can from a meaning, and the group of words would be a false statement. idk. i was just totally thrown off by the fact that the test was contradicting in nature, by, in the instructions saying "you must assume these are true" and then throwing something at us that cannot be true.

EDIT:

Spoiler

idk if it was the implied reason for the answer, but if you are to presume the first 2 are correct, no matter how ridiculous, this should have been an easy freebee. for question 3, the first 2 parts are just random claims that you are to assume are true, and the statement questioning the validity is saying "these presumptions are false" im not sure if it was the intended reasoning, but if you are to automatically assume the presumptions are true, and the statement is saying "the presumptions are false" then, by the instructions, the statement is invalid.
meh. i can relax on this now.

My thoughts exactly.

 

[Saeros]

If Logic is not Truth then wtf do we use it for? Tell me, is Logic or Truth better in your opinions?

My understanding is that the tests were only asking for the validity of the aruments. An argument is valid if the premises and the conclusion are related in such a way that if the premises were true, the conclusion would be undeniable. That means that you have to ignore the specific meaning of the words, and their truth, and analyse the argument in a more logical way. for example:

P1. All [men]<--(A) are [mortal]<--(B) == (A) is (B)
P2. [Socrates]<--(C) is a [man]<--(A) == (C) is (A)
C. [Socrates]<--(C) is [mortal]<--(B) == (C) is (B)
​

This argument is valid because the premises necessitate (entail) the conclusion. The truth (soundness) of the premises can only be discussed once the validity is established. Since the argument is presented in a way that the premises entail the conclusion, once the soundness of the premises has been established, the conclusion is undeniable. In my example, If you accept that the two premises, that men are mortal, and that socrates is a man is true, then you can't deny the conclusion that socrates is mortal. This is because the conclusion is included in the premises, so you can't accept the latter and deny the former.

 

[useless username]

15 on the first one... as far as the second one goes, I was too lazy to do it. :/ maybe later.

Remeber, an argument is valid if and only if it is impossible for all of the premises to be true, and the conclusion false.

In other words, the truth values can be any possibility except all true premises and a false conclusion.

 

[Ermine]

13/11

 

[semicolon]

15/13. Interesting test, got me thinking

I got caught out on Q11 with the fallacy of correlation: my brain unconsciously added an 'all' in "All events in the world are caused by all other events that precede them."

 

[DarkGreen]

Saeros you told how to take them, which was objectively, but I can't get past this sense that they were wrong that something is telling me they violated something. Why am I so angry about this? Nevermind that because I'm getting off the thread topic. I'm truly sorry I bothered people.

 

[Dogod]

14/15

Only open if you've done the test already.

Spoiler

Answer 3.
a) Both premises in this syllogism are untrue.
b) Words constitute all the content of any premise.
- Therefore the words in this syllogism are all false.

The question should first be evaluated statement by statement.

First off, it is impossible to decide whether or not a) is true or false, therefore it would be incorrect to make a statement suggesting it to be either.

"This statement is untrue." Which would make it true? However, it is clearly stated to be untrue. This is what they mean by paradox. This should be enough to invalidate the conclusion since it clearly states 'words' to be false, while it should be impossible to determine.

The secondary consideration is whether or not the concept of 'words' can be 'false'. The concept of 'false' is only meaningful when applied in the context of a logical statement. A 'word' alone is not enough to form a logical statement, and therefore should not philosophically be possible to be 'false'.

Spoiler

Actually, premise A is not a paradox. That can only happen if there is no way for it to be true or false. Statement A can be false, though, if statement B is true, with no paradox at all.
If statement A was "This statement is untrue" as you said, then it would be a paradox, but that wouldn't work with the question.
Question 3 could be better worded like this:
A) Premise B is untrue
B) Words constitute all the content of any premise.
- Therefore the words in premise B are all false.
This wording doesn't take away from the intended fallacy of the argument, and it doesn't introduce the problem of the paradox.

 

[pjoa09]

13/9

i didnt get the robber question. i was wondering what is beak...
but i argue i am correct. its up, it is going to go down. so it is going to go down.

also george orwells

ofcourse its two people he just fucking said it...

1st test was understandable, second was like hmmm couldve been more clear

 

[Madoness]

Of course the premises are false. But the point of these exercises were to determine if the argument is logical or not. Whether or not the premise is wrong, the argument is still logical. It forces one to look at things objectively.

Plus even if logic tells the answer is invalid.

 

[IndigoSensor]

I am actually surprised I did as well as I did. I am terrible with pure logic:

test 1: 13/15
test 2: 11/15

 

[kantor1003]

I scored better on the second one. Really enjoyed the test.
first: 13/15
second: 14/15

 

[catatonic]

first : 15/15
second : 14/15

 

[Jah]

first 15
second 15


easy.


What's with the murder questions anyway ?
Should have the option of "maybe".

you can't conclude it unless one of the premises is straight up "Mary Killed Bob".

 

[Jah]

13/9

i didnt get the robber question. i was wondering what is beak...
but i argue i am correct. its up, it is going to go down. so it is going to go down.

also george orwells

ofcourse its two people he just fucking said it...

1st test was understandable, second was like hmmm couldve been more clear

Does it say they are "going up" or that they "are up" ?

the premise is only "if it goes up, it comes down" not saying anything about things that already are up.

 

[crippli]

Spoiler

I disagree that this is invalid;
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.

I did consider that the word predict and examination is a sloppy term. But in premise a the composition is established. Would the conclusion have been invalid if one concluded?
-The chemical composition of water is established.

The answer why it was invalid.
Invalid. 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. There is an ongoing debate within philosophical circles as to whether water must conform to the molecule H2O. Some argue that it is logically possible for a substance to appear exactly as water and yet still be of a different chemical composition.

I mean, it's irrelevant that it's logically possible for another substance to appear as water with a different chemical composition. If another substance is composed as premise a, then it is water, even if it's not water.

In my opinion premise b is not needed. And the conclusion is valid.

 

[pjoa09]

Does it say they are "going up" or that they "are up" ?

the premise is only "if it goes up, it comes down" not saying anything about things that already are up.

They claimed ambiguity. But in the stricter sense of logic you are correct. I was thinking they had to get 'up' before 'beak' and did. So you they gotta go 'down'. Didn't consider spawning by default as 'up'.

Damnit, again 15/9 lol.

 

[walfin]

15,12

 

[nexion]

I did it again and got 14 and 11 respectively. If I had spent a bit more time thinking I could have done better on the second one.

I find it really helps to turn these types of questions into logical statement that don't have any words, but rather are made of variables and implication chains (the words don't matter anyway). The general rule is that unless there is direct implication, you're not dealing with a valid argument.

Spoiler

15.
a) If murder is wrong, then getting little brother to murder is wrong.
b) Murder is wrong.
- Therefore getting little brother to murder is wrong.

x->y
x
-
therefore y

Logic in a nutshell.

Of course, than you have questions like these:

Spoiler

14.
a) George Orwell said inside every fat person there is a thin person trying to get out.
b) Billy Bunter was a fat person.
- Therefore Billy Bunter was really two people.

Which the test marks as invalid but admits that it would be perfectly valid if you took a more literal interpretation (and even suggests that you reward yourself with an extra point if you do so.

The fatal mistake people far too often make is assume that logic necessarily has any relevance to what might be considered 'truth.'

 

[crippli]

Spoiler

14.
a) George Orwell said inside every fat person there is a thin person trying to get out.
b) Billy Bunter was a fat person.
- Therefore Billy Bunter was really two people.

Which the test marks as invalid but admits that it would be perfectly valid if you took a more literal interpretation (and even suggests that you reward yourself with an extra point if you do so.

The fatal mistake people far too often make is assume that logic necessarily has any relevance to what might be considered 'truth.'

Spoiler

I didn't think too much about it. Like that question. The conclusion was that Billy was two people. But it doesn't make it true just because George Orwell said so. Therefor invalid. Also, when thinking more on the question, even if you have a thin person inside you, doesn't make you two people. Third, premise b states that Billy is just one person.

What I am wondering, is who that person inside Billy is, and why does he or she try to get out?

 

[EyeSeeCold]

I find it really helps to turn these types of questions into logical statement that don't have any words, but rather are made of variables and implication chains (the words don't matter anyway). The general rule is that unless there is direct implication, you're not dealing with a valid argument.

Venn diagram helps too.

 

[EyeSeeCold]

14 / 15 (93%)
The only one I got wrong from test #1 is question 15. Though I was unsure of question 14, but got it right.

Spoiler

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.

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

11 / 15 (73%)

Question 10 had confusing semantics.

Ones I got wrong:

Spoiler

Answer 2.
All rational arguments concerning the economy and the banking crisis must be considered conscientiously. However some of the arguments one hears from economists are clearly not rational.
- Therefore one should appreciate that some of the arguments economists propound must not be considered conscientiously.

Invalid. One could construe the premises and the conclusion as all being true, that does not seem unreasonable. However the argument is not formally deductive because the subject of the first premise (rational arguments) is divided in the second premise and one part is now the subject (arguments) and the other part (rational) becomes a new predicate.
The first premise says only that all rational arguments should be considered. It does not say that others, including irrational arguments, should not be considered.
To see what is happening one can replace the terms in another syllogism of the same form which makes the fallacy more apparent.

Answer 6.
a) The man was stabbed to death.
b) Mary was seen leaving the scene of the crime shortly after the time of the murder.
c) Blood found on Mary's trousers was the same as the victim's.
d) Only Mary's fingerprints were found on the murder weapon.
e) No other people were witnessed near the scene of the crime.
f) Mary's DNA was found on the victim's body.
g) The CCTV evidence showed only Mary stabbing the man shortly before he died.
h) Mary admitted that she had carried out the murder.
- Therefore Mary committed the murder.

Invalid. Strong inductive argument only, not deductive. Strictly this is neither valid nor invalid because it is an inductive argument and only deductive arguments qualify for validity.

Answer 10.
a) Without procreation there would be no evolution of any creatures.
b) Evolution does occur.
- Therefore creatures must be motivated towards procreation.

Invalid. Procreation does not necessarily entail motivation. Some evolutionary biologists have committed the fallacy. Although procreation is a necessary condition for biological evolution it does not follow that all creatures are motivated as such. It may be the case that pleasure is the motivating factor and the result of procreation was an accidental oversight!

Answer 11.
a) All events in the world are caused by other events that precede them.
b) Dusky evenings always precede dark nights.
- Therefore the dusky evenings cause it to be dark at night.

Invalid. Fallacy of correlation - A further problem is that the logical form is: All As are caused by being preceded by some Bs; D precedes E; therefore D causes E. D may not be one of the ‘some’ events.

 

[Hadoblado]

Yeah I got question 15 wrong too. The phrasing at the time seemed ambiguous, but in light of the a very strict definition of validity I now see I was wrong.

 

[nexion]

14 / 15 (93%)

Spoiler

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.

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

Yeah I got question 15 wrong too. The phrasing at the time seemed ambiguous, but in light of the a very strict definition of validity I now see I was wrong.

Induction Fallacy. Science perpetuates this fallacy of logic all the time though it doesn't care too much. The thing to remember about inductive arguments is that they are always invalid.

By the way, question 15 on test one might also be considered a semantic game (or nightmare).

 

[Hadoblado]

My brain actually farted here. I wasn't confused about whether it was deductive/inductive inference, I somehow got caught up on whether or not we could predict this composition whether or not we would be correct in doing so. We can in reality predict anything, but they would be hollow words if there is zero probability of these predictions coming true. I got red-herringed the fuck out of. by looking at the truth value of the conclusion instead of the validity of the argument.

I see induction as a fallacy only if people do not consider its limitations. Science is a systematic inductive process, it is incredibly useful if you don't look too far beyond the data.

 

[Latte]

15 and 14.

Number 12.

Spoiler

Answer 12.
a) Whatever goes up must go down.
b) The train robbers are up before the beak.
- Therefore the train robbers will be sure to go down.

Invalid. ‘Up’ and ‘Down’ are used in different senses, therefore an ambiguity is committed.

I thought about it for a considerable time and reasoned that even though "up" in B is figurative, in the context of one being figurative the other can be regarded in a figurative sense too. It often is used figuratively. In fact, it is chiefly used in a figurative sense today. The the meaning of "up" in "up before the beak" falls under commonly accepted usage parameters of "what goes up must go down".

Hrmph.

About the water thing... the premises say nothing absolute about what future examination results will say. A matter different from whether what they will examine will still be like it was.

 

[sheepie]

15 & 14.

I studied logic at university recently so I kind of know all the tricks. The second murder one got me though, started thinking too hard about reality versus the actual logical content. They use the term 'beyond reasonable doubt' for a reason.

 

[Teohrn]

15/15.

The second test was harder than the first - I had to think more through it.

Question 14 on nr.2 the hardest, however, that there is a thin person inside every fat person is not an established fact, it is George Orwell's opinion (and of course, it's not meant literally). Although if one does take it as a fact, it's actually correct. So in truth, it can be valid or invalid depending on how you interpret it.

This was probably unnecessary though, and perhaps even wrong or badly explained.

 

[ummidk]

14/15 (got 15 wrong, was pretty unsure on that one too, oh well)

15/15

also george orwells

ofcourse its two people he just fucking said it...

doesn't say george orwell is always right, or ever right, for that matter, just says he said it.