Begging the question by Eric Lippert (Fabulous Adventures In Coding):

“Suppose I asked “why are diamonds very hard but butter is very soft?” and you answered “diamond and butter are both made out of atoms; the atoms of diamonds are hard and the atoms of butter are soft.” You would have begged the question; your answer to my question “why are some things hard and some things soft” is “because some things are made out of stuff that is hard and some things are made out of stuff that is soft” – that is, you’ve avoided answering the question by providing an “explanation” that itself cannot be understood without answering the original question – namely, why is some stuff hard and some stuff soft? This pseudo-explanation has no predictive power; it doesn’t tell us anything new, it just circles back on itself. The explanatory assumption – that some atoms are hard and some atoms are soft – is stronger than the thing we are trying to investigate – the hardness and softness of two substances.”