planetdan

Wednesday, April 06, 2005 :::

Logic is tough.

I like to think that I'm pretty rational and that I have a gift for logical thinking, but I got this very basic logic quiz wrong on the first try. Oopsie:

There are four cards. If a card has a vowel on one side, it must have an even number on the other. Out of the four cards below, which two cards would you need to turn over to test this rule?

Answer from Wikipedia: E (via modus ponens) and 7 (via modus tollens). Most chose E and 4, committing the logical fallacy of affirming the consequent, and choosing a test that might confirm but which could never falsify the hypothesis.

See? I'm dumb. Speaking of logic and Wikipedia, you should also read the definitions of all the logical fallacies that people make when trying to debate or argue. You know those people who start a heated debate about some hot-topic media event and then try to prove their point by making some ridiculous illogical arguement or personal attack or irrational statement that doesn't adhere to the constraints of logical thinking? And politicians? Logical fallacies are their bread and butter. They think you won't catch on to their false logic, but some people out there actually understand this stuff. They will also help you critically analyze "fair and balanced" news reports and op-ed pieces. Not that you should be reading op-ed pieces because your mind will go to mush if you do that too often.

I wish my brain could hold all of this important information.

::: posted by dan at 11:32 PM :: [ link ] :: (9) comments

Comments are Closed On this Post

9 previous comments:

I'm dumb too...

By

Roba, at 7:57 AM

Yeah I totally chose E and 4. Damn. I'm a sucker.

By

Biglug, at 8:09 AM

I tried to trick it and pick the two that I knew weren't the obvious. Still wrong. I guess I'm dumb too for trying to out smart the game.

By

katie, at 1:11 PM

actually, if you read what it says you only need to turn over "E" because it only says that the reverse of the vowel must be an even number. it says nothing about the converse or inverse being true.

By

Anonymous, at 11:44 PM

I completely disagree with this logic. The puzzle says that only that "if a card has a vowel on one side it must have an even number on the other." It does not say that all even number cards have a vowel on the back, so you would need to flip the 4 as well.

By

Anonymous, at 1:07 PM

ha-HA! I picked 7!!!! Woot!!

Do I get a pay raise for that?

Actually Anon#2 you just proved the point of the lesson. What purpose is served by flipping the 4? Maybe all evens have vowels, maybe not. It doesn't affect the original arguement.

-anon#3

By

Anonymous, at 4:04 PM

Hello. Long time reader, 1st time poster. I love puzzles so I had to comment. This took me a bit of thinking but I’m pretty sure I’ve got it.. Turning over the E confirms the rule if you see an even number. Turning over the 7 makes it conclusive if you see a consonant - because seeing a vowel would disprove the rule. Turning over the four does nothing because a consonant could have an odd or even number on the other side. Turning over the K also does nothing since you could see an odd or even number as well.

By

Serge, at 11:14 AM

This is so funny, because I had to present an example of a logical fallacy in class today. My example was pretty lame. If I had only read your blog beforehand...

By

Robert, at 12:57 AM

We are being asked to test a hypothesis as it may apply to the un-turned cards. There is no way to do this with only two cards and the one rule.

That is what anonymous 11:44 PM and 1:07 PM were saying. It can be disproved with one or two cards depending on the result. It can not be proven with two cards unless you assume the converse or inverse apply. The puzzle needs to be worded differently.

By

Anonymous, at 7:36 AM

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