That would be “order” or “structure”. Randomness is the absence of structure. The logic will goes like this, an equation or procedure by definition defines a structure, therefore it cannot create true randomness.
The only kind of procedure that can create randomness is one that is infinitely long. So the statement is an objective explanation why its not possible.
From the subjective point of view, it’s a matter of degree. So the digits of Pi may appear random, but it in fact has structure that has recently been discovered.