Name that logical fallacy

Heisenberg

Well-Known Member
Well it's a quiet night, all good people are asleep and dreaming, but we atheists and skeptics can still have some fun, and practice at the same time.

One important skill to develop when defending reason and sanity is to recognize logical fallacies and other manipulative tricks. On RUI they are usually obvious, but sometimes if you are not aware of reasoning mistakes, a logical fallacy can lead to a pretty compelling argument. Some fallacies can be nuanced and confusing. Lets take a look at both the obvious and subtle mistakes we are likely to see in this forum, practice our skill and learn something at the same time.

If you feel you can identify the fallacy, please name it, describe it, and give an alternate example of when we hear it. Feel free to drop some riddles of your own, but make sure to give multiple examples.

Lets start with an easy yet common argument we see quite a bit.

1) I believe the Loch Ness monster and other sea creatures exist because the ocean and bodies of water are hard to explore, and we have only seen a fraction of what is down there.

2) We do not have any evidence of alien visitors or spacecraft, therefore aliens do not exist.

3) I believe ESP is possible because humans only use 10% of their brain. Who knows what is possible if we learn to use the entire thing.

In addition to some factual errors, all of these arguments share a common fallacy. What is it?
 

cannabineer

Ursus marijanus
Dang!! I forgot about the middle bit.

OK my example: I have seen no trees in my travels through this county. There aren't any.

The fallacy holds because i'm citing absence of evidence as evidence of absence.

I'll see yer demerit and raise you one: "loose"? Heisenberg, I'm uncertain about you sometimes. ~ggg~
cn

<edit> Note to self. Read ALL the instructions.
 

Heisenberg

Well-Known Member
The argument from ignorance can be compelling if stated a certain way. Many people get offended when you point out an appeal to ignorance because they mistakenly assume you are calling them ignorant. The problem with argumentum ad ignorantiam is that when someone is asked to supply support for their premise, they use ignorance as evidence. Saying that the ocean is vast and unexplored in no way supports the idea of sea monsters. Saying that we have no evidence of aliens in no way indicates aliens don't exist.

The argument from ignorance and appeal to ignorance are actually two different things, with one creating a false dilemma, but anytime someone points to the lack of knowledge as support for supposed knowledge you can be sure it is a fallacy.
 

blazinkill504

Well-Known Member
The argument from ignorance can be compelling if stated a certain way. Many people get offended when you point out an appeal to ignorance because they mistakenly assume you are calling them ignorant. The problem with argumentum ad ignorantiam is that when someone is asks to supply support for their premise, they use ignorance as evidence. Saying that the ocean is vast and unexplored in no way supports the idea of sea monster. Saying that we have no evidence of aliens in no way indicates aliens don't exist.

The argument from ignorance and appeal to ignorance are actually two different things, with one creating a false dilemma, but anytime someone points to the lack of knowledge as support for supposed knowledge you can be sure it is a fallacy.
last time i checked we got evidence of fuckin aliens bein here all around us.
 

Heisenberg

Well-Known Member
Dang!! I forgot about the middle bit.

OK my example: I have seen no trees in my travels through this county. There aren't any.

The fallacy holds because i'm citing absence of evidence as evidence of absence.

I'll see yer demerit and raise you one: "loose"? Heisenberg, I'm uncertain about you sometimes. ~ggg~
cn

<edit> Note to self. Read ALL the instructions.
Your demerit is removed for pointing out a spelling error, and subsequently reinstated for pointing out a spelling error!

Next fallacy

1) Psychics must be real because celebrities like Paris Hilton and Regis Philbin use them often.

2) McDonald's fries are america's favorite, so they must be the best.

3) It's silly to think Elvis is still alive because everybody knows he is dead
 

cannabineer

Ursus marijanus
Your demerit is removed for pointing out a spelling error, and subsequently reinstated for pointing out a spelling error!

Next fallacy

1) Psychics must be real because celebrities like Paris Hilton and Regis Philbin use them often.

2) McDonald's fries are america's favorite, so they must be the best.

3) It's silly to think Elvis is still alive because everybody knows he is dead
Argumentum ad populum. (The first shades into appeal to authority.)

It describes the idea that the majority is invariably correct.

Example (are we still doing this?): Dude, nobody I know owns a Mitsubishi. They obviously suck.

As for my demerit, i offer argumentum ad baculum: So long as i don't have any demerits ... nobody gets hurt. ~cackle!~
cn
 

blazinkill504

Well-Known Member
Argumentum ad populum. (The first shades into appeal to authority.)

It describes the idea that the majority is invariably correct.

Example (are we still doing this?): Dude, nobody I know owns a Mitsubishi. They obviously suck.

As for my demerit, i offer argumentum ad baculum: So long as i don't have any demerits ... nobody gets hurt. ~cackle!~
cn
i happen to enjoy my mitsu!! lol

boils down to people will believe anything the majority does. ie mindless followers
 

Heisenberg

Well-Known Member
Argumentum ad populum. (The first shades into appeal to authority.)

It describes the idea that the majority is invariably correct.

Example (are we still doing this?): Dude, nobody I know owns a Mitsubishi. They obviously suck.

As for my demerit, i offer argumentum ad baculum: So long as i don't have any demerits ... nobody gets hurt. ~cackle!~
cn
Yes, and great example. You win the prize, which is dinner with Carrot Top.

The appeal to popularity, or bandwagon fallacy, is obviously a poor way to judge the truth value of a statement. No matter how many people think Clay Aiken is a woman, he's still a man.
 

Heisenberg

Well-Known Member
1) I wore this shirt then I pitched a perfect game, therefore this is my lucky shirt and I can never wash it.

2) Many people try marijuana before moving on to harder drugs like heroin. Cannabis is a gateway drug.

3) Most rapist admit to having pornography on their computer, pornography leads to rape.
 

NewGrowth

Well-Known Member
All fallacies are in fact true, because our understanding is relative to the knowledge we have obtained. No one has yet given mankind all knowledge so it seems more likely that most of our conclusions are false; at least in part. bongsmilie
 

Heisenberg

Well-Known Member
All fallacies are in fact true, because our understanding is relative to the knowledge we have obtained. No one has yet given mankind all knowledge so it seems more likely that most of our conclusions are false; at least in part. bongsmilie
We have already covered the appeal to ignorance. :) Any good skeptic or person of reason already acknowledges that any answer we have is an approximation of the truth, with some being more accurate than others. For example, the conclusion that my cat is a male seems to be a pretty close estimate, but is subject to change given a sufficiently supported argument. The knowledge we do have is backed by evidence based reasoning which attempts to avoid fallacies and defeatist attitudes such as this one.
 

blazinkill504

Well-Known Member
1) I wore this shirt when I pitched a perfect game, therefore this is my lucky shirt.

2) Many people try marijuana before moving on to harder drugs like heroin. Cannabis is a gateway drug.

3) Most rapist admit to having pornography on their computer, pornography encourages rape.
ways to validate an action by some so called sign
 
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