First we had Occam's Razor. Then we had Hickam's dictum. In confusion, we invented the Duck Test. But finally, we have the one trite epistemological aphorism to rule them all: Newton's flaming laser sword!

Coined by philosopher Mike Alder, Newton's flaming laser sword is a particularly confining device, trimming all of human knowledge to that that can be proven through scientific experimentation, right now. It is commonly summarized as "what cannot be settled by experiment is not worth debating", although Alder himself gives a somewhat longer definition:

"In its weakest form it says that we should not dispute propositions unless they can be shown by precise logic and/or mathematics to have observable consequences. In its strongest form it demands a list of observable consequences and a formal demonstration that they are indeed consequences of the proposition claimed."

His first example of this is the famous quandary, what would happen if an immovable object were confronted with an unstoppable force? The correct answer, he proposes, is to ignore the question until such a time that we have both an immovable object and an unstoppable force at hand, and can test the matter empirically. He has a point.

However, this principle disallows any debate of things such as free will and ethical matters such as rights (Alder suggests that ethics might be reduced to factors such as evolution and game theory). Whether this is a feature or a bug is a matter of personal preference. Alder does admit that humans should perhaps not live by the laser sword for matters of social convenience, as normal humans might be expected to have opinions on religion, politics, popular movies, sex, philosophy, and other inconsequential and unscientific things.

Newton's flaming laser sword is sometimes known by the less impressive name of Alder's razor, for obvious, if boring, reasons. Alder admits that laser sword is named in honor of Newton's statement of hypotheses non fingo ('I contrive no hypotheses'), which broadly speaking might be treated as a synonym.

Reference: Mike Alder (2004). Newton's Flaming Laser Sword, Or: Why Mathematicians and Scientists don't like Philosophy but do it anyway. Philosophy Now. 46: 29–33.