The following illustration highlights the difference between unlikely theories which are manipulated to fit the evidence at great lengths with theories which are strongly confirmed by the evidence.

“Dave believes dogs are spies from planet Venus. He views any canine with great suspicion, for he believes they are here from Venus to do reconnaissance work. Dog’s Dave supposes, secretly send their reports back to Venus, where the rest of them fiendishly cunning alien species are meticulously planning their invasion of earth. Their spaceships will shortly arrive from Venus to enslave the human race and take over the world.

…

DAVE: It’s only a matter of weeks now! The spaceships will arrive and then you’ll wish you’d listened to me. We must act now – let the government know!

MARY: Look, Dave, dogs are pretty obviously not space invaders, they are just dumb pets. Dogs can’t even speak, for goodness sake, let alone communicate with Venus!

DAVE: They can speak – they just choose to hide their linguistic ability from us. They wait till we leave the room before they talk to each other.

PETE: But Venus is a dead planet, Dave. It’s horrifically hot and swathed in clouds of acid. Nothing could live there, certainly not a dog!

DAVE: Dogs dont live on the surface of Venus, you fool – they live below, in deep underground bunkers.

MARY: But then how do earth-bound dogs communicate with their allies on Venus? I’ve got a dog, and I’ve never found an alien transmitter hidden in his basket.

DAVE: They dont use technology we can observe. Their transmitters are hidden inside their brains!

MARY: But Pete is a vet, and he’s X-rayed several dog’s heads, and he’s never found anything in there!

PETE: In fact, I once chopped up a dog’s brain in veterinary school – let me assure you, Dave, there was no transmitter in there!

DAVE: You’re assuming their transmitters would be recognisable as such. They are actually made of organic matter indistinguishable from brain stuff. That’s why they dont show up on X-rays. This is advanced alien technology, remember – of course we cannot detect it!

MARY: But we dont detect any weird signals being directed at Venus from the earth.

DAVE: Of course, we dont – like I said, remember, this is advanced alien technology – beyond our limited understanding!

PETE: How do dog’s fly spaceships? They dont even have hands. So they cant hold things like steering wheels and joysticks.

DAVE: Really Pete. Think about it. You are assuming that their spacecraft will be designed to be operated by human hands. Obviously they wont. They’ll be designed to be maneuvered by a dog’s limbs, mouth, tongue, and so on.

You can see how this conversation might continue ad nauseum. Mary and Pete can keep coming up with evidence against Dave’s beliefs that dog’s are Venusian spies. But, given sufficient ingenuity, Dave can always salvage his core theory. He can continually adjust and develop it so that it continues to ‘fit’ the evidence.” (p73-74; S, Law, Believing Bullshit, How not to Get Sucked into an Intellectual Black Hole)