There are four stages to a distinctly contemporary approach to philosophy. There is something like this approach in the thought experiments in ancient philosophy (like the ring of Gyges) and in the doctrine of possibility that Anselm adopts in his Ontological Argument, but it never was a dominant element in either Ancient or Medieval argumentation.
1.) Ockham’s Razor. One of Ockham’s fundamental principles is that you shouldn’t believe things you don’t need to. You ought to cut out everything not necessary. Said another way, you’re obliged to throw out everything whose opposite is possible.
2.) Descartes through Hume. Descartes adopts as a pure heuristic the idea that nothing allowing the least doubt is necessary. By the time we get to Hume, this is clearly stated as a conceivably criterion: anything conceivable is also possible, i.e. not necessary.
3.) Any narrative or made-up name is conceivable. Our ability to tell a story about something or even say what a word means is taken as proving its real possibility. We don’t need to prove anything is possible (the way, say, that St. Thomas had to prove that the beatific vision was metaphysically possible.*) it’s taken as given as possible if we can tell a story about it, or even if we can coherently describe what we might mean.
4.) The storytelling principle. And so we hit on a distinctly contemporary belief that we should not believe anything if we can tell a story about it being otherwise or we are obliged not to believe something that is opposed to an idea that we made up.
*It’s crucial to note the auxiliary verb “can” in the title and in the proof. He’s trying to prove something can be, not that it ever happens.