## Logical Fallacy Game

Philosophical, mathematical and computational logic, linguistics, formal argument, game theory, fallacies, paradoxes, puzzles and other related issues.

### Logical Fallacy Game

I thought it might be fun if we started a "name that logical fallacy" game, in the tradition of the physics game and the biochem games. I'll start with a fairly easy one. The goal is to name the logical fallacy employed in the following statement. Whoever gets it correct asks the next question, and so on. If nothing else, it's good practice.

Here's the statement:

"The earth must be flat, because nobody has ever proven otherwise."

I know it's an easy one, but I wanted to get the ball rolling.
cloudy-a

I'm undecided between "argument from ignorance" and "lie". :)

BioWizard

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:) funny

Right, argument from ignorance or Argumentum ad Ignoratiam. The argument that something must be true because it has not been proven otherwise.

You're up funny man!
cloudy-a

Ok cool, here's mine. Also simple:

"The earth is not spherical, hence it must be flat".

BioWizard

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Black-or-White Fallacy

What fallacy did Penn Jillette use below?

Bob Murch, spirit board collector: "There's been thousands of years of accounts of ghosts and hauntings, and if those are true, you know, surely a spirit board can work."

Penn Jillette:"So, if those aren't true, a spirit board can't work? Cool!"

Source: Penn & Teller, "Ouija Boards/Near Death Experiences", B.S.!
Sparky

How about 'The Argument from Ignorance must be true, because nobody has ever proven otherwise.'
SmallMind

Or how about one from the '30s in Germany: 'If the courts admit one slippery-slope argument it will be followed by another, and soon the whole court system will be tied up in slippery slope arguments.'
SmallMind

I think the rules state you have to correctly answer before asking a question.
Sparky

Oops. Sorry, misunderstood game. Fallacies are listed in Wikipedia.
SmallMind

Sparky wrote:Black-or-White Fallacy

That's correct. It's a false dichotomoy.

BioWizard

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Sparky wrote:What fallacy did Penn Jillette use below?

Bob Murch, spirit board collector: "There's been thousands of years of accounts of ghosts and hauntings, and if those are true, you know, surely a spirit board can work."

Penn Jillette:"So, if those aren't true, a spirit board can't work? Cool!"

Source: Penn & Teller, "Ouija Boards/Near Death Experiences", B.S.!

Is it "questionable cause" ?

BioWizard

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Is it "questionable cause" ?

Nope. It's a type of formal fallacy. Here's a clue:

Bob Murch: If p, then q.

Penn Jillette: So, if not-p, then not-q.
Sparky

Is it improper transposition? If not-P then not-Q does not necessarily follow from if P then Q?
cloudy-a

Is it improper transposition?

Sparky

What's the logical fallacy employed in the following statement:

"Good and evil are constantly battling it for control of the universe"

(Modified from an example given in Wikipedia.)
cloudy-a

Sparky wrote:
Is it "questionable cause" ?

Nope. It's a type of formal fallacy. Here's a clue:

Bob Murch: If p, then q.

Penn Jillette: So, if not-p, then not-q.

I took the if not-p, then not-q to be equivalent to "p is the cause of q" (even though I realize now that they can be linked without the link being a causative one). That's why I answered "Questionable cause fallacy", and in doing so committed that very fallacy...

So cloudy-a. Hints?

BioWizard

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In an extremely brief visit to formal logic, a very fuzzy awareness persisted that calls for some corrective assistance from experts. There was a vague suspicion that the relation between logical objects never exceeded 'implies'. That is, the relation 'causes' absolutely never appears anywhere. Is this correct?
SmallMind

It is also notable that the exercises here and elsewhere are distinguishable even when posed for different circumstances. This means they are recognizable by structure. To recognize structures and remember them is a distributed faculty, showing up in individuals often to a striking degree in every imaginable discipline, all of which have some characteristics which are indisputably structural. The point I'm getting at is that a painless way to introduce the student to logic is to increase an awareness of the importance of structures everywhere, even to everyday living. They are already using it when they arrive, but don't know it.
SmallMind

The current logical-fallacy-containing statement is:

"Good and evil are constantly battling it out for control of the universe"

Hint, the fallacy is contained wholly in the words: "Good and evil are constantly battling"
cloudy-a

This is a tough one. Is it the "Figure of Speech" fallacy?

The phrase figuratively gives "good" and "evil" human-like qualities by implying that they can battle, which may cause confusion.
Sparky

Yep Sparky. I learned it as reification fallacy, but I think it is the same thing (?)
Anyhow, you're up. :)
cloudy-a

Therefore, there are some bad habits that everyone has.
Sparky

Bump. Anyone? This one is easy.
Sparky

Fallacy of Redundancy, or tautology?
SmallMind

Nope.
Sparky

Sparky wrote:Everyone has some bad habits.
Therefore, there are some bad habits that everyone has.

Illicit Conversion?

kidjan
Active Member

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kidjan wrote:
Sparky wrote:Everyone has some bad habits.
Therefore, there are some bad habits that everyone has.

Illicit Conversion?

No, but very close.
Sparky

Existential assumption?
cloudy-a

Close. An existential fallacy would go more like this:

All Higgs Bosons are particles.
Therefore, some particles are Higgs Bosons.

In this example, the proposition lacks existential import. That is, it does not assert the existence of the Higgs Boson. However the validity of the conclusion rests on the existence of the Higgs Boson.

The "bad habits" example is a slightly different fallacy if you look closely. Do you want me to give the answer?
Sparky

### Re: Logical Fallacy Game

cloudy-a wrote:"The earth must be flat, because nobody has ever proven otherwise."

Actually, the earth has been proven not to be flat. Straight deductive logic.
lucaspa

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