Perpetual Motion Machine Argument

Inventors routinely claim patents for perpetual motion machines. The patent office is no longer required to investigate them, because they, by construction, violate thermodynamic laws.

A PerpetualMotionMachineArgument is an argument that is so fundamentally flawed that it requires no specific rebuttal or analysis, because it is based on demonstrably false premises or it violates known laws.

The problem is even the smartest people can't tell which arguments are fundamentally flawed. Two hundred years ago the best minds in the world scoffed at the idea of big rocks falling out of the sky. It was obvious that rocks didn't fall from the sky. Rocks were too heavy to get up into the sky. This doesn't mean the patent office should start investigating perpetual motion machines, but be mindful of what you scoff. -- EricHodges

I see it a matter of probability. If the last 500 PMM patents turned out to be bogus, then #501 is probably bogus also based on past history. Even if a PMM is possible, the chance that any given PMM patent application is the valid one is very small. Thus, the patent office cannot find an economic argument to check every one. If they follow what they do with software, they would simply grant the PMM patent and let the courts straiten it all out. There does not seem to be much punishment for granting questionable patents these days. --top

I understand the term "Perpetual motion machine argument" in quite the opposite way, actually. A subset of ReductioAdAbsurdum?, where the absurd conclusion is that a PMM could be constructed.

One of my favourite examples: Some geometric solids are unstable on one or more sides; that is, if you set them on that side on a flat, level surface, they will fall over because of an imbalance in mass. However, no solid can be unstable on every side, even if you allow for non-uniform density.

The proof: if it existed, just set it down on the flat, level surface, and it will fall over (no matter how you orient it). Having fallen over, it will land on some other side, where it is also unstable, etc; thus the solid is a PMM. -- KarlKnechtel

Interestingly, I have constructed a tetrahedron that was unstable on three of its four faces. If you draw a digraph with four nodes representing the faces and edges pointing from A to B if the tetrahedron falls to B when placed on A, it's interesting to determine what graphs can be realised. The one I built felled A -> B -> C -> D.

How about a ball? It's unstable on every side (having an infinite number of them, each being a single point), and if preturbed it will easily fall over onto another an adjacent "side". :)
It's not "unstable", it's in neutral equilibrium.

Similar argument: Take any triangle oriented vertically with bottom side parallel to the floor. If you drape a rope over the top of this triangle such that each of the two top sides are exactly covered, the rope will not fall off the triangle. Proof: You can construct a loop of rope suspended only by each end with the ends of equal height above the floor. This rope follows a symmetrical catenary curve. If the first rope would fall off one side or another of the top of the triangle, you could attach the symmetrical catenary rope to each end of the top rope. In this way, as one piece fell off the top it would be replaced from the other side, giving a perpetually spinning rope. --AndyPierce (who kind of butchered this argument, but you get the idea I hope)