"Funny man. The prediction of your supposed theory is that something will not happen?"
"Okay. I have a "theory" that pigs fly. Here's my prediction which, if false, will discredit the idea: "No human will ever be observed in the lab to grow three arms and fly into outer space while speaking in tongues." If this event is observed, my theory will be falsified."
Sometimes I get the impression I am wasting my time debating with morons. If you have a theory that pigs fly, then your theory would obviously be falsified if you ever see a pig fly. So my alternative theory, that "pigs can't fly" would be falsified if we ever observed a pig fly. My "prediction," therefore, is that we will never see a pig fly. Yes, that's a prediction that something will *not* happen. So what?
Don't bother replying. If you do, please understand that I have no time to reply to your pedantic nonsense.
John: Pigs can't fly.
Fred: Oh, so you believe the "pigs-can't-fly" (PCF) theory, eh?
John: I suppose you could say that.
Fred: That's not even a theory. A theory must be falsifiable. Give me one prediction that your theory makes that, if found false, would discredit your theory.
John: Well, basically the theory predicts that a pig will never fly.
Fred: Ha! That's not a *positive* prediction. It's just a prediction that something will *not* happen!
John: Well, yes. But if the prediction were falsified because we observed a pig flying, then the PCF theory would be discredited. Of course, we certainly don't expect to see that happen, do we.
Fred: Ha! So you've admitted that your PCF theory cannot be disproven. We'll never see a pig fly, so your theory cannot be disproven! So it is not a valid scientific theory! Your silly trick won't work.
John: I give up. I don't have time for this nonsense. You "win."
Fred: Your weak arguments just can't stand up, so that's why you are quitting.
John: Whatever you say, Fred. Whatever you say.