I've never seen a blue whale before. However, we have all these evidence -- anecdotal, pictoral, historical, empirical -- that it exists. Therefore, I come to the conclusion that a blue whale exists in nature, even though it is highly unlikely I will ever directly observe one.
That's not true! I believe that blue whales don't exist because I've never seen one, so all your 'evidence' doesn't matter. In fact, I believe that flying whales exist, and blue whales don't.
Alright, then. Where's the evidence for the flying whales?
You fool! There's no need for evidence for flying whales! All you have to do, is believe in them!
Well.. that doesn't mean that blue whales don't exist, right?
What I'm saying is that you can't show me directly that blue whales exist, so I can say that they don't. In fact, this further bolsters my theory, because if you can't show me a blue whale in the flesh, they don't exist, and this means that flying whales are real.
Erm. You can't show me a flying whale either, can you?
SILENCE FAITHLESS HEATHEN!
Okay... Well, you're entitled to believe what you want to believe. That's cool. I'll keep on thinking that blue whales exist and you keep believing in your flying whales, is that okay?
No, it's not! I think EVERYONE should believe the same things I do.
That's not nice. Why should everyone have to believe what you believe? I mean, I don't think any single world view should be taught in school over others, right? Unless, of course, you have empirical proof, and it can be shown scientifically that--
LA LA LA I'M NOT LISTENING. ANYWAYYYYYY, I propose that, from now on, when biology teachers talk about blue whales, they must also discuss the possibility that blue whales don't exist. They must also talk about the possibility of flying whales. No, I'll call it the "Theory of Flying Whales" because it sounds much better that way.
But there's no evidence for flying whales! You can't teach that flying whales may exist because you've never actually seen a blue whale! You do know that parading around the weaknesses of another theory does not in itself consitute a basis for a new theory, right? You need observations, data, evidence for your own theory!
I'm going to change the definition of 'evidence', then!"
....Huh??
From now on, in the state of Sasnak, "evidence' can also include strong beliefs that an alternative exists. We will include faith as evidence. That's the ticket. That way, the Flying Whale Theory can be accepted as a valid alternative, because we have faith in it."
....
Also, I will get the President to support this.
....
Yeah, we will defeat the BlueWhale-ists once and for all. Curse Charles BlueWhale for coming up with the Blue Whale theory."
...You sad, sad person.