"There's two scientists on lab coats observing a spider. They shout JUMP! and the spider jumps.
They proceed to remove one of it's legs and repeat the procedure. They shout JUMP! and the spider jumps...
After some time of repeating the procedure the poor spider has no legs. They shout JUMP! and it doesn't do a thing.
The scientists then come to verify their useful hypothesis: ..spiders use their legs to listen..."
Also the more complex a prediction is, the harder it is to get right by mistake. Example: GPS Satellite timekeeping.
"There's two scientists on lab coats observing a spider. They shout JUMP! and the spider jumps.
They proceed to remove one of it's legs and repeat the procedure. They shout JUMP! and the spider jumps...
After some time of repeating the procedure the poor spider has no legs. They shout JUMP! and it doesn't do a thing.
The scientists then come to verify their useful hypothesis: ..spiders use their legs to listen..."