God exists. So go ahead and break out the dice! As long as we understand that chance only means lack of knowledge of cause.
1 It is also apparent from the foregoing that divine providence does not take away fortune and chance from things.
2 For it is in the case of things that happen rarely that fortune and chance are said to be present. Now, if some things did not occur in rare instances, all things would happen by necessity. Indeed, things that are contingent in most cases differ from necessary things only in this: they can fail to happen, in a few cases. But it would be contrary to the essential character of divine providence if all things occurred by necessity, as we showed. Therefore, it would also be contrary to the character of divine providence if nothing were to be fortuitous and a matter of chance in things.
3 Again, it would be contrary to the very meaning of providence if things subject to providence did not act for an end, since it is the function of providence to order all things to their end. Moreover, it would be against the perfection of the universe if no corruptible thing existed, and no power could fail, as is evident from what was said above. Now, due to the fact that an agent fails in regard to an end that is intended, it follows that some things occur by chance. So, it would be contrary to the meaning of providence, and to the perfection of things, if there were no chance events.
4 Besides, the large number and variety of causes stem from the order of divine providence and control. But, granted this variety of causes, one of them must at times run into another cause and be impeded, or assisted, by it in the production of its effect. Now, from the concurrence of two or more causes it is possible for some chance event to occur, and thus an unintended end comes about due to this causal concurrence. For example, the discovery of a debtor, by a man who has gone to market to sell something, happens because the debtor also went to market. Therefore, it is not contrary to divine providence that there are some fortuitous and chance events among things.
Notes Failure to understand all aspects and condition of a cause is chance. As is also proved in the next argument. Remembering, of course, cause is not only efficient cause.
5 Moreover, what does not exist cannot be the cause of anything.
Hence, each thing must stand in the same relation to the fact that it is a cause, as it does to the fact that it is a being. So, depending on the diversity of order in beings, there must also be a diversity of order among causes.
Now, it is necessary for the perfection of things that there be among things not only substantial beings but also accidental beings. Indeed, things that do not possess ultimate perfection in their substance must obtain such perfection through accidents, and the more of these there are, the farther are they from the simplicity of God. From the fact, then, that a certain subject has many accidents it follows that it is a being accidentally, because a subject and an accident, and even two accidents of one substance, are a unit and a being accidentally; as in the example of a white man, and of a musical, white being.
So, it is necessary to the perfection of things that there should also be some accidental causes. Now, things which result accidentally from any causes are said to happen by chance or fortune. Therefore, it is not contrary to the rational character of providence, which preserves the perfection of things, for certain things to come about as a result of chance or fortune.
6 Furthermore, that there be order and a gradation of causes is important to the order of divine providence. But the higher a cause is, the greater is its power; and so, its causality applies to a greater number of things. Now, the natural intention of a cause cannot extend beyond its power, for that would be useless. So, the particular intention of a cause cannot extend to all things that can happen.
Now, it is due to the fact that some things happen apart from the intention of their agents that there is a possibility of chance or fortuitous occurrence. Therefore, the order of divine providence requires that there be chance and fortune in reality.
7 Hence it is said: “I saw that the race is not to the swift … but time and chance in all” (Sirach 9:11), that is, among things here below.