Name the fallacy (Or: Justify your belief in the existence of China)

Factual Questions
1

A dialogue between Jones and Smith…

Jones: “Smith, look at that wall! It must be the biggest wall in the whole world!”
Smith: “There is a larger wall in China.”
Jones: “What do you mean!?”
Smith: “China has a ‘Great Wall’ that is larger than this one.”
Jones: “Preposterous! How do you know that?”
Smith: “I read about it.”
Jones: “But have you ever been to China and seen this wall?”
Smith: “Well no, but…”
Jones: “Ah ha!”
…is Jones committing a logical fallacy by implying that Smith cannot reasonably attest to the existence of a wall he’s never personally seen? Neither seem to fit exactly, but it seems like it could almost be characterized as an argument from incredulity or an argument from ignorance.

Thoughts?

2

In a real conversation Smith would reply, “I may not have personally seen it, but millions of other have, and I’ve seen numerous pictures, films and even live broadcasts from the Great Wall of China, from various unrelated sources.”

3

Cite?

4

You might want to choose a different story. In this story, Jones is not really making any assertions at all. He is merely pointing out that Smith is relying on hearsay.

Personally, I think Jones is making a valid point, especially given the ridiculous urban legends that I’ve heard over the years.

5

How can you believe anything?
You might be just having a very realistic dream…

6

What I’m gathering is that it isn’t fallacious to deny someone’s assertion simply because it is based upon hearsay.

[QUOTE=Czarcasm]
In a real conversation Smith would reply, “I may not have personally seen it, but millions of other have, and I’ve seen numerous pictures, films and even live broadcasts from the Great Wall of China, from various unrelated sources.”
[/quote]

If this is Smith’s only recourse, it seems like Jones could stall debate endlessly (assuming Smith had the patience) simply by asserting that a trip to China was in order. That feels… wrong… somehow.

7

Solipsism is all well and good… but for the purposes of this thread I’m assuming that I’m not a brain in a jar. I may be a brain in a jar, but that possibility is not useful to me and I’ve boldly chosen to ignore it.

8

Logically, Smith can not know for an absolute certainty that there is a wall. However by reviewing multiple reliable and unrelated sources the probability of of error becomes inconceivably small (and not ‘The Princess Bride’-style inconceivable, more like spontaneous human combustion inconceivable).

9

There are pieces of evidence for the existence of the Great Wall of China, or the Loch Ness Monster, or the Moon Landing. Actually seeing it for yourself is one piece of evidence; testimony from your wife’s cousin’s hairdresser is another piece of evidence. Different pieces of evidence have different weight. Some people may weigh certain pieces of evidence differently than others; in many cases, we would term over reliance on a particular kind of evidence, such as personal experience, to be a fallacy, but I don’t know what the Latin name for that fallacy would be.

A scientist would say that the preponderance of evidence supports the existence of the Great Wall of China, but a perfect scientist would not say that the existence of the Great Wall of China is *proven *even if he is looking right at it.

10

Things that may or may not be implied in an everyday conversation don’t really fall within the realm of logical argument. In your example Jones has not actually stated that he does not believe the Great Wall of China exists, he’s only expressed skepticism that the Great Wall is larger than whatever wall they’re looking at. Although the Great Wall is in fact the longest wall in the world, it’s not fallacious to question whether this is true. While Smith is correct in this situation, we don’t know if Smith is generally reliable or if he’s in the habit of inventing or exaggerating things.

If Jones were to say that he didn’t believe that the Great Wall existed because he’d never heard of it before then that would be an argument from ignorance. If Jones were to keep demanding more and more evidence to prove the existence of the Great Wall (“Okay, it has a Wikipedia entry, but have you seen it yourself?”) then that would be shifting the goalposts, but I’m not familiar with any special term for demanding an unreasonable amount or type of evidence from the very beginning. But from the conversation in the OP it’s not clear that Jones is saying he will accept nothing short of a first-hand account of the Great Wall as proof or if he’s just questioning Smith’s claim about the size of the Great Wall. Since I can’t tell what his argument is I can’t say whether it’s logical or not.

11

It just seemed to me that those who stubbornly reject things which are “obviously true” ought to be guilty of some sort of fallacious reasoning. “Argumentum ad Headupassum” or something like that, ya know?

When your arm is off, it’s just off whether you deny it or not.

12

Sorry, I suppose I lost my point trying to make the OP more flavorful. For the purposes of this discussion, Jones has deliberately pursued this line of inquiry knowing that Smith hasn’t been to China hoping to bully him and win the argument that the hypothetical wall is, in fact, bigger than the Great Wall by default.

13

:smiley:

14

It isn’t obviously true that some wall in another country is larger than this great big wall right here. That the Great Wall of China is the longest wall in the world is a pretty widely known fact, but if Jones has somehow never heard this before then the truth of it is not self-evident.

That’s still not an argument, it’s just an explanation of Jones’s motives. He sounds like a jerk, but being a jerk isn’t fallacious in and of itself.

If it is Jones’s position that since Smith can’t prove that the Great Wall is longer than the hypothetical wall then the Great Wall isn’t longer than the hypothetical wall, then that’s argument from ignorance.

15

What’s that joke about a physicist, a mathematician, and an engineer (I think these are the players) as they determine the veracity of what they see being, in fact, a cow?

ETA: We want Latin for “argument from ignorance”!

16

Okay, argumentum ad ignorantiam.

17

Jones is arguing that the evidence of one’s own eyes is somehow fundamentally and categorically different from any other kind of evidence, which is Special Pleading.

18

Okay, how do you know the earth is round? I mean, have you actually seen it yourself from outer space? Well, have you?

And how do you know that matter is made of atoms? Yes, yes, I know you’ve read all about it in your high school science textbooks, and you’ve been told about whats-his-name who discovered all this, and the experiments he did. But what evidence have you seen with your own eyes?

And how do you really know that Social Security is going to run out of money in 10 years? Because some TV talk show hosts said so? Have you done the arithmetic yourself? And did you really read the entire Omamacare Act yourself?

The whole question of how certainly you know most of what you know all boils down to where you got the information from, and who you really trust to give you the Straight Dope. Did you see Obama’s birth certificate with you own eyes? And were you there in Honolulu or Nairobi or wherever, watching with your own eyes, when that same original was created?

Okay, here’s one where there might have really been some question of who to believe:

Randy Shilts, late AIDS victim and activist, wrote an essay in which he essentially tells his readers that everything the government tells you is shit, designed to maintain calm and prevent massive public panics. The Centers for Disease Control is just a shill for the government, or insurance companies, or something like that.

But can AIDS really be transmitted from one person to another via mosquitos? Sure, if you like having anal sex with mosquitos. (Yes, he really wrote that.) But calm down, don’t worry, and don’t lock up all AIDS patients like lepers, because you really can’t get AIDS from mosquitos!

Now, how did Randy Shilts know that? Did he do the relevant research himself (or observe while others did)? Or did he just take the word for some abstract experts how claimed to have somehow discovered that fact? And might not those abstract experts themselves – just possibly – have been researchers with, or funded by, the Centers for Disease Control?

What you believe depends a lot on who you trust for your information, and also a whole lot on what you wanted to believe to begin with.

19

There is no spoon.

20

I didn’t even know mosquitos have anuses. But why should I believe you, anyway?