Topic: Whats the name of this logical fallacy?

[skydivephil]

Suppose someone claimed airplanes needs wings to fly thefore no vehicle can fly without wings.  What would be the name of this logical fallacy?

[Ajzzz]

Hasty generalisation.

[ting-bu-dong]

Depending on how it's worded, it sounds like the problem would be the premise (i.e. wings being necessary to achieve flight) rather than the logic. When you assume that wings are necessary for flight, it does follow that vehicles without wings can't fly.

[Horseman]

Wouldn't it be a composition error? Individual of class A has characteristic B, therefore all members of class A have characteristic B.

[Xptical]

I'm having a hard time coming up with an airplane (or any aircraft, really) that doesn't have wings.  This has no bearing on the fallacy, just an observation about the statement.

[unixTechie]

You're forgetting about helicopters, balloons, and rockets?

[Sordid]

You're forgetting about helicopters

They do have wings, or more accurately airfoils, typically affixed to a centrally located rotating shaft.

Aircraft can be either aerostats (i.e. lighter than air; balloons, blimps, airships, that sort of thing) or aerodynes (which achieve lift by moving an airfoil through the air; i.e. conventional airplanes, helicopters, and various hybrid designs like autogyros and tiltrotors).

[ting-bu-dong]

The point is that an aircraft requires lift, not wings. Wings are not the only way of generating lift, which is what the original statement assumes. If it were the only way to generate lift, the statement would be correct, which means the logic is sound.

[Sordid]

So it's unstated major premise, then. ("wings are the only way to generate lift")

[seaotter]

Just false premise. Aircraft require wings for flight. Sorry it does say airplanes.

[Ajzzz]

Aircraft requiring wings for flight would be the conclusion in how I interpreted the sentence. I think it's clearly stated in the sentence that no vehicle can generate lift without wings, so it's clearly not an unstated major premise, it's not the premise, it's the conclusion. Anything following "therefore" in the sentence usually wouldn't be the premise.

[Sordid]

No, it says "thefore no vehicle can fly without wings". Fly ≠ generate lift.

[Johnny Slick]

If (flies) then (wings)
Therefore if !(wings) then !(flies)

Actually, I think that's modus tollens, which is not a fallacy at all but one of the oldest tautologies in the book. The real problem here is that the premise "if something flies then it has wings" is, as stated, demonstrably false.

[Ajzzz]

No, it says "thefore no vehicle can fly without wings". Fly ≠ generate lift.

If that's the case, then the sentence isn't saying anything about generating lift, since before the "therefore" it also refers to flying.

[Henning]

I think Ajzzz was right first. Hasty generalization, specifically Guilt by association. If we take the wording of it literally, it says because one kind of flying vehicle (airplanes) needs wings to fly, they all must need wings to fly. Simpler: Airplanes have wings, airplanes are a flying vehicle, therefore all flying vehicles have wings. Simple generalization.

Depending on your definition of fly and wing, the "therefore" could indeed be true, but this train of logic won't get you there!