Magic

Magic is a craft practised by people who are expert in the art of illusion or maya.
They define their goals in a subjective manner focusing on perceived reality.
Most people cannot distinguish between absolute and perceived reality, so they are easily deceived by magic.

Magic is inherent in the statement

"if goals are defined in a relative/subjective manner without inherent contradictions, they can be achieved (yes even what seems impossible, even something that you cannot even visualize at that point of time) "

If the target is to "Make people believe that a human being has disappeared" and is defined exactly as that, it can be done.

Define it as "Make the human being disappear" and it cannot.