This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

Does a balloon fly or float?

skydivephil wrote:This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

It's the Fallacy of Hasty Generalisation. or Generalisation from the Particular. Also known as Leaping to Conclusion.

The argument is of the form: [tex] [\exists X, \exists Y, \exists Z : P(X), P(Y), P(Z) ] \implies [\forall W: P(W)] [/tex]

It is taking a list of particular cases and leaping to the conclusion that it's true for the general case.

This is an especially egregious case in that the list consists of just one case. It's leaping from "a plane needs such for such" to "all things need such for such".

Greyman wrote:

skydivephil wrote:This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

It's the Fallacy of Hasty Generalisation. or Generalisation from the Particular. Also known as Leaping to Conclusion.

The argument is of the form: [tex] [\exists X, \exists Y, \exists Z : P(X), P(Y), P(Z) ] \implies [\forall W: P(W)] [/tex]

It is taking a list of particular cases and leaping to the conclusion that it's true for the general case.

This is an especially egregious case in that the list consists of just one case. It's leaping from "a plane needs such for such" to "all things need such for such".

But, as per teh Chairman's point, there is also a fallacy of equivocation in there as well. The "flight" of a plane (where one is looking at the opposing forces of lift/gravity and thrust/drag) is mechanically different from the "flight" of a (presumably LTA) balloon.

If its a balloon that's been blown up and then let go, it can indeed fly. It doesn't fly very well or indeed for long but they can usually make it across the room, making amusing fart noises as they go. Totally shit as a form of transport though.
Maybe there isn't a logical fallacy.

Balloons have been flown around the world , stayed in the air for 55 day (thats longer than any aeroplane ) lfown to over 120,000 feet (higher than any aeroplane) and reached speeds of over 200mph, belive me they can fly. Thanks for your help

skydivephil wrote:This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

It is actually logically valid and therefore not a logical fallacy.

Planes and balloons are examples of objects. The argument is about which properties an object must possess in order to be able to fly. i.e. the necessary condition that they have wings and a tail (where wings + tail is a conjunction).

In standard categorical form the sentence could be: all things that fly are things with wings and a tail.

If you draw a Venn diagram it will be clear that the argument is valid.

Likewise, in propositional form we could put:

If X can fly (P)
then X has wings and a tail (Q)

If X doesn't have wings and a tail (notQ) then X can't fly (notP). This shows it's valid.

The actual fault with the argument is that the premise that wings and a tail are necessary for flight is false - so the argument is unsound - not invalid.

Planes don't need tails to fly.

http://en.wikipedia.org/wiki/Flying_wing

So as the premise "A plane needs wings and a tail to fly" is false, the full statement is actually logically valid but its semantic content is nil. Anything follows from a falsehood by the principle of explosion.

Assuming a balloon cannot fly because it has no wings is also a non sequitur as the conclusion
does not follow from the premise [ if one ignores the distinction between flying and floating ]

skydivephil wrote:This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

Non-sequitur. The conclusion doesn't follow from the premise(s).

Rumraket wrote:

skydivephil wrote:This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

Non-sequitur. The conclusion doesn't follow from the premise(s).

It does actually follow, as the premise is false. Anything follows from a falsehood. So it can't be a non-sequiteur.

Veida wrote:

Rumraket wrote:

skydivephil wrote:This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

Non-sequitur. The conclusion doesn't follow from the premise(s).

It does actually follow, as the premise is false. Anything follows from a falsehood. So it can't be a non-sequiteur.

No, anything doesn't follow from a falsehood.

You are confusing validity with soundness. If the premise is false, but the conclusion follows, then the argument is valid but not sound.

In this case, even if the premise was true "a plane needs wings and a tail to fly" it still would not follow that therefore a balloon cannot fly because it has neither. So the primary fallacy of the argument (the argument as a whole, not whether the premise is actually true) is that it is invalid, the conclusion doesn't follow. So it's a non-sequitur.

Rumraket wrote:

Veida wrote:

Rumraket wrote:

skydivephil wrote:This is logically invalid but what is the name of the logical fallacy being used?
"A plane needs wings and a tail to fly, a balloon has neither so it cant fly".

Non-sequitur. The conclusion doesn't follow from the premise(s).

It does actually follow, as the premise is false. Anything follows from a falsehood. So it can't be a non-sequiteur.

No, anything doesn't follow from a falsehood.

Yes, it does.

Rumraket wrote:You are confusing validity with soundness. If the premise is false, but the conclusion follows, then the argument is valid but not sound.

In this case, even if the premise was true "a plane needs wings and a tail to fly" it still would not follow that therefore a balloon cannot fly because it has neither. So the primary fallacy of the argument (the argument as a whole, not whether the premise is actually true) is that it is invalid, the conclusion doesn't follow. So it's a non-sequitur.

I'm working under the assumption that we're operating in worlds that are reasonably similar to ours, where we have the normal laws of physics and where words mean what they usually mean. I.e., that all possible interpretations of the argument are in such worlds. Then, there is no interpretation in which the premise is true. How is it then a non-sequiteur?

Veida wrote:

Rumraket wrote:

Veida wrote:

Rumraket wrote:
Non-sequitur. The conclusion doesn't follow from the premise(s).

It does actually follow, as the premise is false. Anything follows from a falsehood. So it can't be a non-sequiteur.

No, anything doesn't follow from a falsehood.

Yes, it does.

Look, the truth or falsity of the premise is not relevant to what follows from the premise. We are talking logical structure, not physics.

Think about it, suppose the premise was true. Suppose it was actually true that "a plane needs wings and a tail to fly". Would it then follow that a balloon could not fly because it has neither? No. Well then it cannot be relevant whether the premise is true or not, to what follows from it. Regardless of whether the premise is true, the conclusion still doesn't follow, because planes=/=balloons. It's that simple.

We could forget about planes, balloons and physics entirely and just state the argument like this:
A needs n and m to do t, B has neither so it can't do t.

That doesn't follow, it's an invalid argument. Why doesn't it follow? Because B =/= A. So there are at least two things wrong with the argument. It is invalid, in that the conclusion doesn't follow. So that's a non-sequitur fallacy. The reason it commits a non-sequitur is because it generalizes the requirements for A (n+m) to do t, to also apply to B. But this has not been established, so that conclusion cannot be derived from that single premise alone.

Rumraket wrote:Look, the truth or falsity of the premise is not relevant to what follows from the premise. We are talking logical structure, not physics.

You are assuming that there is an interpretation where the premise is not false. I question that.

Rumraket wrote:Think about it, suppose the premise was true. Suppose it was actually true that "a plane needs wings and a tail to fly". Would it then follow that a balloon could not fly because it has neither? No.

Now you are assuming in the one case (regarding the premise) that the usual laws of physics do not hold, while in the other case (the ballon) that they do. You seem to be certain that there is a world where the laws of physics are such that the premise is true while the conclusion is false. I don't know why you believe that.

Rumraket wrote:Well then it cannot be relevant whether the premise is true or not, to what follows from it. Regardless of whether the premise is true, the conclusion still doesn't follow, because planes=/=balloons. It's that simple.

We could forget about planes, balloons and physics entirely and just state the argument like this:
A needs n and m to do t, B has neither so it can't do t.

That doesn't follow, it's an invalid argument. Why doesn't it follow? Because B =/= A. So there are at least two things wrong with the argument. It is invalid, in that the conclusion doesn't follow. So that's a non-sequitur fallacy. The reason it commits a non-sequitur is because it generalizes the requirements for A (n+m) to do t, to also apply to B. But this has not been established, so that conclusion cannot be derived from that single premise alone.

For your generalization of the argument, you are right.

I'm not so sure about the actual argument.

Rumraket wrote:

Veida wrote:

Rumraket wrote:

Veida wrote:
It does actually follow, as the premise is false. Anything follows from a falsehood. So it can't be a non-sequiteur.

No, anything doesn't follow from a falsehood.

Yes, it does.

Look, the truth or falsity of the premise is not relevant to what follows from the premise. We are talking logical structure, not physics.

Think about it, suppose the premise was true. Suppose it was actually true that "a plane needs wings and a tail to fly". Would it then follow that a balloon could not fly because it has neither? No. Well then it cannot be relevant whether the premise is true or not, to what follows from it. Regardless of whether the premise is true, the conclusion still doesn't follow, because planes=/=balloons. It's that simple.

We could forget about planes, balloons and physics entirely and just state the argument like this:
A needs n and m to do t, B has neither so it can't do t.

That doesn't follow, it's an invalid argument. Why doesn't it follow? Because B =/= A. So there are at least two things wrong with the argument. It is invalid, in that the conclusion doesn't follow. So that's a non-sequitur fallacy. The reason it commits a non-sequitur is because it generalizes the requirements for A (n+m) to do t, to also apply to B. But this has not been established, so that conclusion cannot be derived from that single premise alone.

This is the closest to correct.

It's much simpler, however, to say that "the argument is nonsense. Hence there is no fallacy, because there is no argument to begin with."

It's closer to being a slight-of-hand magic trick. Since there's no hand, it would have to be described as a slight-of-mutter trick instead.

In a typical slight-of-hand, disappearing object trick, the magician uses how he/she waves his hands about, to distract the observer from seeing that he/she palms the object, and only appears to pass it from one hand to the other.

In this statement, the author did the same thing. Waving words about vaguely, starting with an incomplete premise statement (the terms "plane" and "fly" are not defined), and following with a premise statement about a balloon. The phrasing is designed to IMPLY an "if-then" statement, but no actual "If" or "then" are said out loud. Just as a magician encourages the audience to "see" him/her move an object from one hand to the other while not actually doing so, the arguer here encourages the reader to "see" the If and Then statements, but never makes them.

Hence, nonsense.