What makes an idea "scientific"? Not proof — the opposite

Most people assume a scientific claim is one backed by lots of confirming evidence. Philosopher Karl Popper argued the reverse: piling up confirmations proves almost nothing, because you can always find examples that fit your pet theory. What separates science from pseudoscience, he said, is falsifiability — whether a claim makes a risky prediction that could turn out to be false.

Consider the difference between "the sun will rise tomorrow" and "everything happens for a reason." The first sticks its neck out — if the sun didn't rise, the claim would be dead. The second explains any outcome equally well, so no observation could ever refute it. For Popper, that second kind of statement isn't wrong so much as unscientific: it forbids nothing, so it tells us nothing testable about the world.

This flips how we judge good theories. A strong scientific idea is one that dares to be refuted and survives repeated attempts to knock it down. Einstein's relativity impressed Popper precisely because it predicted something specific and checkable — starlight bending by an exact amount — that could have failed. By contrast, theories that "explain everything" often explain nothing.