The same facts, two stories.
Take a recurring fear — that a headache means something is seriously wrong, that you've offended someone, that the house isn't safe. There are always two ways to explain why the thought keeps coming back. Theory A: the danger is real, and the worry is an appropriate response to it. Theory B: the danger is not the problem — the problem is worry about the danger, and the checking, reassurance, and vigilance that worry produces. The facts are identical. The explanation is what differs.
Where the idea comes from.
This framing grew out of cognitive accounts of anxiety developed by clinical psychologists such as Paul Salkovskis, who argued that what keeps fear going is often not the feared situation itself but the way a person responds to their own thoughts about it. Setting Theory A against Theory B turns a vague dread into something testable: instead of asking "is the danger real?", you ask "which explanation better fits everything I've actually experienced?"
Testing the two against the evidence.
Once both theories are written down, you can weigh them. How many times has the feared catastrophe actually happened, despite the thought arriving hundreds of times? What does all that checking and reassurance-seeking achieve — lasting calm, or a brief dip before the worry returns? If Theory A were true, you'd expect the danger to have materialised by now; if Theory B is true, you'd expect the worry to grow the more you feed it. Usually the lived evidence points one way.
Why Theory B is often the better bet.
The honest answer is that you can rarely prove a feared catastrophe is impossible — certainty isn't available, and chasing it is part of the trap. But you can ask which theory explains more of what you've seen, and which one, if you acted on it, would make your life better. For many people the pattern is clear: the catastrophe keeps not happening, while the worrying keeps costing. That makes Theory B not just more comforting but more accurate.
Living as if Theory B were true.
The shift isn't to win an argument with yourself but to try the other theory on. If Theory B fits, then the helpful move is to do less of what worry demands — less checking, less reassurance, less avoidance — and watch what happens. The fear may protest at first; that's expected. Over time, acting as though the worry (not the world) is the problem tends to be the thing that finally lets it settle.