Falsifiability
Overview
Falsifiability is that attribute of an assertion which makes it possible to prove the assertion's correctness or incorrectness. If there is no observation which could, in principle, show the assertion to be wrong, then there is correspondingly no opposite observation which could show the assertion to be correct.
Note that an "observation" can be defined as broadly as necessary in order to allow for very rarefied observations, e.g. "If God exists, then there will be a Judgment Day" could be falsified – although not immediately! – by the absence of a Judgment Day prior to the extinction of humankind. (If the extinction of humankind is taken to be Judgment Day, then the assertion is completely unfalsifiable, as the only way to prove it wrong would be for humankind to survive forever and for someone to observe this.) We might say, however, that such observations are practically non-falsifiable (unless Judgment Day happens to come along and thereby proves that God does, in fact, exist as defined by the assertion).
The methods of science generally insist that any assertion must be falsifiable in order to be taken seriously.
Examples
Frequently cited examples of non-falsifiable assertions include:
- Some entities invented to highlight the illogic of much religious doctrine:
- The existence of God is often seen as non-falsifiable because no specific testable assertions are made about the nature of His/Her/Its existence.
- Direct creation theories, in which all the scientific evidence for millions of years of evolution and billions of years of geology and cosmology were created, along with the Earth, 10,000 years ago or less, are generally non-falsifiable because of the supposition that any evidence which seems to argue against them was in fact "planted" by an omnipotent being (God) who can violate (or perhaps operated before the existence of) the laws of physics and/or logic.