2. A contingent event differs from a necessary event in point of the way in which each is contained in its cause. A contingent event is so contained in its cause as that it either may not or may ensue therefrom:* whereas a necessary event cannot but ensue from its cause. But as each of these events is in itself, the two do not differ in point of reality; and upon reality truth is founded. In a contingent event, considered as it is in itself, there is no question of being or not being, but only of being: although, looking to the future, a contingent event possibly may not come off. But the divine mind knows things from eternity, not only in the being which they have in their causes, but also in the being which they have in themselves.
3. As from a necessary cause the effect follows with certainty, with like certainty does it follow from a contingent cause, when the cause is complete, provided no hindrance be placed. But as God knows all things (Chap. L). He knows not only the causes of contingent events, but like-wise the means whereby they may be hindered from coming off. He knows therefore with certitude whether they are going to come off or not.*
6. The knowledge of God would not be true and perfect, if things did not happen in the way that God apprehends them to happen. But God, cognisant as He is of all being of which He is the principle, knows every event, not only in itself, but also in its dependence on any proximate causes on which it happens to depend: but the dependence of contingent events upon their proximate causes involves their ensuing upon them contingently.* God therefore knows sundry events to happen, and to happen contingently: thus the certitude and truth of divine knowledge does not remove the contingency of events.
7. When it is said, 'God knows, or knew, this coming event,' an intervening medium is supposed between the divine knowledge and the thing known, to wit, the time to which the utterance points, in respect to which that which is said to be known by God is in the future. But really it is not in the future in respect of the divine knowledge, which existing in the instant of eternity is present to all things. In respect of such knowledge, if we set aside the time of speaking, it is impossible to say that so-and-so is known as non-existent; and the question never arises as to whether the thing possibly may never occur. As thus known, it should be said to be seen by God as already present in its existence. Under this aspect, the question of the possibility of the thing never coming to be can no longer be raised: what already is, in respect of that present instant cannot but be. The fallacy then arises from this, that the time at which we speak, when we say 'God knows,' co-exists with eternity; or again the last time that is marked when we say 'God knew'; and thus a relation of time, past or present, to future is attributed to eternity, which attribution does not hold; and thus we have fallacia accidentis.*
8. Since everything is known by God as seen by Him in the present, the necessity of that being true which God knows is like the necessity of Socrates's sitting from the fact of his being seen seated. This is not necessary absolutely, 'by necessity of the consequent,' as the phrase is, but conditionally, or 'by necessity of the consequence.' For this conditional proposition is necessary: 'He is sitting, if he is seen seated.' Change the conditional proposition into a categorical of this form: 'What is seen sitting, is necessarily seated': it is clear that the proposition is true as a phrase, where its elements are taken together (compositam), but false as a fact, when its elements are separated (divisam).* All these objections against the divine knowledge of contingent facts are fallacia compositionis et divisionis.
That God knows future contingencies is shown also by the authority of Holy Scripture: for it is said of Divine Wisdom, It knows signs and portents beforehand, and the issues of times and ages (Wisd. viii, 8): and, There is nothing hidden from his eyes: from age to age he regardeth (Ecclus xxxix, 24, 25).
1.66 : That God knows things which are not
1.68 : That God knows the Motions of the Will