"Moving the goalposts" is a debate tactic that is not intellectually honest.
It means that a debater may issue a challenge, e.g.,
"Show me a case where a new species has been seen to arise."
This is shown and the debater replies with:
"Ah, but that is still a dog/rat/worm or whatever." They are now asking for something at a higher taxon than species.
In other words the original requirement is met and instead of acknowledging that the debater "moves the goal posts" to some other requirement. This is a
very common practice in the evolution vs creation debate by the creationists.
It is intellectually dishonest.