TWELFTH LECTURE
In the perspectives of modern thought, -- either from the viewpoint of empiricist philosophy, or from the viewpoint of the actual practice of the sciences of phenomena -- the notion of cause has become that of an existential position, to which another existential position is linked de facto. Therefore, in order to know the "cause" or rather the "causes" on which a phenomenon depends, all the existential positions by which this phenomenon is determined must be known.
Thus, even keeping the philosophical notion of cause, the modern mind considers in preference, not the cause, but the concatenation of causes on which an effect depends. If we consider such a concatenation of causes, we are led to distinguish the necessithy by right (this was the necessity with which the ancients dealt) and on the other hand the necessity in simple fact, and to observe that an event can be both contingent and necessary in simple fact: contingent, that is to say, springing from a cause that could be hindered, or springing from a pure interference of causes, no one of which was pre-ordered to this effect; necessary in simple fact, that is to say, entirely determined by the constellation of causes which have been de facto posited in existence, but which could have been not posited in existence, or hindered from producing their effect if another cause had acted. If we imagine the entire constellation of all the causes acting in the universe from the very beginning, even a purely casual event is necessary in simple fact.
Therefore a future contingent event is by itself not foreknowable with certainty. But it can be foreknown by accident, for instance, if we know beforehand the entire constellation of its causes, in certain particularly simple cases.
Nevertheless the future contingent events which can happen in the course of earthly nature cannot be foreknown with infallible certainty by any intelligence, even superhuman, because it would be necessary, in order to foreknow them in this manner, to calculate step by step the entire history of all the causes interfering with one another in the universe. Note only is such a calculation impossible to any intelligence, (except the creative intelligence, which does not need calculating and foreknowing, because it knows everything as present;) but such a calculation would not be a foreknowledge properly called, that is to say, knowing things in their causes, and thus being exempt from exhausting their history; it would be in reality an historical knowledge, obliged to follow the actual fate of every factor in the universe, and finally knowing things not in their causes, but in their actual existence.
As to the acts of free will, they are so contingent that they are neither necessary by right nor necessary in simple fact. Therefore they are absolutely unknowable.