Knowledge comprehends what is known and the relevant states of things. Yet merely knowing a possible outcome does not, by the notion of knowledge alone, specify its actual occurrence.
Two possible times of an event can both fall within knowledge. Knowledge as such does not explain which time is determined for its creation; this function is ascribed to will.
Thus the universality of knowledge and the specification performed by will are distinct meanings. Simply renaming knowledge as will would leave the argument's question unanswered.