How's your logic? (Interesting test)

Post Reply New Topic

Question 12 relates to words meaning multiple things.

It can be reworded:

What rises must fall.
The burglars woke up ("before the beak", whatever that means).
Therefore, the burglars will be arrested.

Number 14, it relates to understanding the metaphor in the first premise. "inside every fat person there is a thin person trying to get out." does not mean there's a separate 2nd person inside that person.

Also, just because George Orwell says something is so does not make it so. The premise is not "inside every fat person there is a thin person trying to get out.", but that someone said "inside every fat person there is a thin person trying to get out.".

Having gotten the questions right, though, does not mean they figured them out. There is, after all, a 50/50 chance of getting each one right by guessing. 25% (on average) of people guessing on those two questions will get them both right.

I got 7, 9, and 13 wrong.

My original thinking was, can't there be reptiles that aren't birds? But I see now, it wouldn't make a difference.


It didn't say "all," so I assumed otherwise. Bleh.


Hmph.

I scored an 8, which was about 52%.

On the "birds are bacteria" question, I answered invalid, because we all know that birds are not bacteria.

87%. Those that I got wrong were due to the language used in the questions. Question 12, for example, "up before the beak," I did not understand.

yuk 73%

I would have done better with formal training. I get the feeling that no matter what I put there would have been a 'trick answer' based on linguistics versus logic. The birds are reptiles question was fun. I used a venn diagram for that (circles in a circle).

I think you're exactly right. I've had a lot of training with the symbols and methods of logic. I had a philosophy of logic class and a discrete structures mathematics class (which I didn't do as well in but learned a LOT) so I'm really used to ideas like the opposite of "if p, then q" is NOT "if q, then p" but rather "if not q, then not p" -- which was not intuitive to me but once it was showed to me, I understood the logic.

We spent a lot of class time learning logic symbols and their precise meanings and then how to manipulate them in figuring something out and we made big charts of possibe results of syllogisms so that we could see what was valid and what wasn't. It made a very big difference in how I think about statements of fact and how I logically think things through.

what on earth does "up before the beak" mean?

i got 93%

i thought the video evidence plus confession busted Mary, but i suppose she could be lying (or unaware that > ), someone could have further stabbed the man (actually killing him while Mary only maimed him) and eliminated his fingerprints, and so on.

glad i wasn't on her jury.

I'm very, very logical and only got 47%. It's more about reading comprehension than how logical you are.

I sat in on a logic class once and they were doing this sort of thing, but more about rules than actual sentences...it was like
A implies F
not not A implies Q
Q implies not A
F is Q by the rule of motus ponus

That's not exactly how it goes obviously, because I'm not a 3rd year philosophy student

If you look at the answer page, you'll see that the problem is that Mary's situation is neither "valid" nor "invalid" because it is inductive reasoning, not deductive, and valid/invalid doesn't apply to inductive, only to deducative.

I think it was a trick question, because if it's neither valid nor invalid, how could you know whether you were supposed to check "valid" or "invalid" in order to indicate that it is neither?

therein lies a problem if you don't speak the language of formal logic.

i didn't even know what inductive / deductive reasoning were, let alone know which would be considered valid. i just knew there could (if not likely) be holes in the evidence, but that it would be enough to convict.

but as you point out, if it doesn't have an answer, it's an invalid question, i would think.

Error: None of the information given indicates that mary murdered him without the addition of external information such as common sense.



Error: the robbers do not go up, they merely are up.

I don't know the difference between inductive and deductive, could someone explain?

I sort of know what inductive and deductive reasoning are but I can never keep straight in my head which is which.

The way I was approaching that question was looking for logic loopholes. It kind of went like this:

a) The man was stabbed to death.

Okay, he was killed, with a sharp instrument. Might have been an accident.

b) Mary was seen leaving the scene of the crime shortly after the time of the murder.

Oh, it wasn't an accident, it was a murder. Mary could have been there accidentally.

c) Blood found on Mary's trousers was the same as the victim's.

Mary could have been his wife or sister and her first reaction was to run up to the body to see if he was still alive and could be resuscitated or helped, getting blood on her pants. She could have been seen leaving the scene shortly after because she was going to find help.

d) Only Mary's fingerprints were found on the murder weapon.

The real murdered could have worn gloves, leaving no prints. Mary could have pulled the knife out of the victim (wrongly) thinking she was helping him. (Never pull out an impaling object as it could have been the only thing keeping the victim from bleeding to death before the ambulance got there.) Or Mary could have seen the knife on the floor and picked it up, thinking "what's this?" before she realized it was a murder weapon.

e) No other people were witnessed near the scene of the crime.

Just because no other people were witnessed, doesn't mean no other people were there. Not seeing something doesn't prove it doesn't exist.

f) Mary's DNA was found on the victim's body.

She could have been overcome with grief and held him to her and wept, just like Maria held Tony after he was killed in "West Side Story". That would be enough to get DNA on him.

g) The CCTV evidence showed only Mary stabbing the man shortly before he died.

oh...okay. Kind of hard to argue with the closed circuit television system . . . very hard to switch tapes to fake Mary stabbing him. Maybe with someone dressed up like Mary. Ockham's Razor, however, suggests the simplest answer which is that Mary stabbed him before he died. But he still could have died from something else or Mary could have been doing something else that looked like stabbing . . .

h) Mary admitted that she had carried out the murder.

Well, that confession pretty much seals it. Anything that could have been circumstantial evidence or could have been explained another way becomes supporting evidence for Mary as the murderer.

Which is why I checked "valid", not even realizing it wasn't deductive reasoning, thus couldn't be valid.

Deductive reasoning goes from premises like:

premise: all humans are mortal
premise: Socrates is a human
conclusion: therefore, Socrates is mortal.

Inductive reasoning is what Sherlock Holmes uses and is more about probability of something occuring than about starting with a premise and making a conclusion. For example:

The sun came up yesterday morning and the morning before that. It has come up every morning that I have been alive and remembered and no one in history has written about a day when the sun did not come up. Therefore, I believe the sun will come up tomorrow morning.

That's not valid or invalid, it's just a statement of probability and belief. Like I believe it's highly probably that Mary was the murderer.

But stuck there in the middle of a bunch of deductions in a test that said it was about deductions, it sneaked right past me. grr...

I got 100% but i had to google "up before the beak" to determine if it was an adage or colloquialism. (which it is was and meant going before a judge) If it meant physically "going up(ward)" then it would've changed the answer.

it's a very basic logic test though, it doesn't contain anything deep though, I don't think one question asked A causes B causes C, so does C cause A? There were no "if and only if" statements. But still an interesting quiz, and I enjoyed taking it.

one of the more interesting tests. i got 70 something percent. I thought some of the questions were ambiguous and did rely on outside knowledge. some of them were easy to understand when i read the explanation. I feel that this is based on very formal logic light the type you may be taught. I don't have a problem with this as i feel it is the best grounding for a good understanding of logic. it makes me want to learn some logic, i think it would help me somewhat.

80 % hmmm not very good

80%.

I didn't realize that question 12's ambiguity was relevant, because I thought we were disregarding the fact that these are nonsense.

I also didn't realize that I should take into account the paradox in 3-- too logical to score 100%, or too dumb? I still don't know.

I think the reason I did so badly is because I took the instructions to mean that I should take all nonsense as sense and go from there.

Question 7 was textbook (I got it right) because it's very clear, the conclusion obviously follows from the premises... and the premises are all false.

And I can see the mistake I made on 8. I converted it into the form "if X, then Y. Y is false. Therefore, X is false."