I have noticed that this term gets thrown around quite often when people debate what's "scientific" and what is not.
What I have NOT found is a definition or explanation of "falsifiability" that is unambiguous, coherent and logical!
Apparently it's an alleged "property" of a theory or hypothesis, which for some mysterious reason makes it "scientific" (whatever that might mean - I'll get back to that later)
So we need a "test" which could tell us whether a theory/hypothesis is "falsifiable" or not. In the context of science any such a "test" should be rigorously and unambiguously defined.
The problem is, the only things I found are ambiguous and nonsensical ramblings made by people who seem very unfamiliar with the clarity, rigor and logical soundness that actual science requires. And I haven't even touched on the issue of how such a "test" would prove that something is "scientific" and what that would really mean.
Let's explore a few examples ... first, wikipedia:
So we have:
"basic statement" - what does it mean? how does it differ from non-"basic statements"? do you just have to "say something"?
"successful or failed falsification" - a theory is falsifiabile if [something], which, in eventual successful or failed falsification [some other stuff] - what is the meaning of falsification here, as it sounds like a circular statement
"must respectively correspond to a true or hypothetical observation" - what's the meaning of "hypothetical observation"? it kinda sounds like oxymoron! are imaginary things are ok? unicorns? aliens? or just scenarios that are imaginary but seem plausible due to similar actual facts that exists or perhaps laws of physics?
OK, let's now explore the concrete example... from the same wikipedia:
1. what if that "basic statement" were not a "true observation" but some imaginary stuff?
2. how about this one: "all swans have two eyes" ... good luck finding a three eyed swan!
OK, now let's try to falsify one popular "theory": "The earth is flat!" - well, this is contradicted by many statements and experiments that back them! So "the earth is flat" is a scientific theory according to Popper! WOW! How does it help us in separating non-scientific stuff from scientific stuff?
We can even try to formulate theories related to imaginary friends: "In every room in every building on earth, there's a green unicorn!" Finding just one room without an unicorn would make the theory "scientific". You can replace unicorns with angels, gods or whatever.
Then there's the nonsense that a theory can only be "disproved" and never "proved" - which is hugely wrong and nonsensical(you might get to "disprove" an infinity of things and won't be able to reach any conclusion)! Actually the whole story about "falsifiability" comes from this philosophical idea of Popper that "nothing is certain" and theories can only be shown to be false. Besides being wrong, is completely unhelpful, as that's not the way we use science to our benefit.
I'll stop here for now.