Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904], at sacred-texts.com
IT is generally agreed upon that God cannot at a certain time acquire knowledge which He did not possess previously; it is further impossible that His knowledge should include any plurality, even according to those who admit the Divine attributes. As these things have been fully proved, we, who assert the teaching of the Law, believe that God's knowledge of many things does not imply any plurality; His knowledge does not change like ours when the objects of His knowledge change. Similarly we say that the various events are known to Him before they take place; He constantly knows them, and therefore no fresh knowledge is acquired by Him. E.g., He knows that a certain person is non-existent at present, will come to existence at a certain
time, will continue to exist for sometime, and will then cease to exist. When this person, in accordance with God's foreknowledge concerning him, comes into existence, God's knowledge is not increased; it contains nothing that it did not contain before, but something has taken place that was known previously exactly as it has taken place. This theory implies that God's knowledge extends to things not in existence, and includes also the infinite. We nevertheless accept it, and contend that we may attribute to God the knowledge of a thing which does not yet exist, but the existence of which God foresees and is able to effect. But that which never exists cannot be an object of His knowledge; just as our knowledge does not comprise things which we consider as non-existing. A doubt has been raised, however, whether His knowledge includes the infinite. Some thinkers assume that knowledge has the species for its object, and therefore extends at the same time to all individual members of the species. This view is taken by every man who adheres to a revealed religion and follows the dictates of reason. Philosophers, however, have decided that the object of knowledge cannot be a non-existing thing, and that it cannot comprise that which is infinite. Since, therefore, God's knowledge does not admit of any increase, it is impossible that He should know any transient thing. He only knows that which is constant and unchangeable. Other philosophers raised the following objection: God does not know even things that remain constant; for His knowledge would then include a plurality according to the number of objects known; the knowledge of every thing being distinguished by a certain peculiarity of the thing. God therefore only knows His own essence.
My opinion is this: the cause of the error of all these schools is their belief that God's knowledge is like ours; each school points to something withheld from our knowledge, and either assumes that the same must be the case in God's knowledge, or at least finds some difficulty how to explain it. We must blame the philosophers in this respect more than any other persons, because they demonstrated that there is no plurality in God, and that He has no attribute that is not identical with His essence; His knowledge and His essence are one and the same thing; they likewise demonstrated, as we have shown, that our intellect and our knowledge are insufficient to comprehend the true idea of His essence. How then can they imagine that they comprehend His knowledge, which is identical with His essence; seeing that our incapacity to comprehend His essence prevents us from understanding the way how He knows objects? for His knowledge is not of the same kind as ours, but totally different from it and admitting of no analogy. And as there is an Essence of independent existence, which is, as the philosophers, call it, the Cause of the existence of all things, or, as we say, the Creator of everything that exists beside Him, so we also assume that this Essence knows everything, that nothing whatever of all that exists is hidden from it, and that the knowledge attributed to this essence has nothing in common with our knowledge, just as that essence is in no way like our essence. The homonymity of the term "knowledge" misled people; [they forgot that] only the words are the same, but the things designated by them are different: and therefore they came to the absurd conclusion that that which is required for our knowledge is also required for God's knowledge.
Besides, I find it expressed in various passages of Scripture that the fact
that God knows things while in a state of possibility, when their existence belongs to the future, does not change the nature of the possible in any way; that nature remains unchanged; and the knowledge of the realization of one of several possibilities does not yet effect that realization. This is likewise one of the fundamental principles of the Law of Moses, concerning which there is no doubt nor any dispute. Otherwise it would not have been said, "And thou shalt make a battlement for thy roof," etc. (Deut. xxii. 8), or "Lest he die in the battle, and another man take her" (ibid. xx. 7). The fact that laws were given to man, both affirmative and negative, supports the principle, that God's knowledge of future [and possible] events does not change their character. The great doubt that presents itself to our mind is the result of the insufficiency of our intellect. Consider in how many ways His knowledge is distinguished from ours according to all the teaching of every revealed religion. First, His knowledge is one, and yet embraces many different kinds of objects. Secondly, it is applied to things not in existence. Thirdly, it comprehends the infinite. Fourthly, it remains unchanged, though it comprises the knowledge of changeable things: whilst it seems [in reference to ourselves] that the knowledge of a thing that is to come into existence is different from the knowledge of the thing when it has come into existence; because there is the additional knowledge of its transition from a state of potentiality into that of reality. Fifthly, according to the teaching of our Law, God's knowledge of one of two eventualities does not determine it, however certain that knowledge may be concerning the future occurrence of the one eventuality.--Now I wonder what our knowledge has in common with God's knowledge, according to those who treat God's knowledge as an attribute. Is there anything else common to both besides the mere name? According to our theory that God's knowledge is not different from His essence, there is an essential distinction between His knowledge and ours, like the distinction between the substance of the heavens and that of the earth. The Prophets have clearly expressed this. Comp. "For my thoughts are not your thoughts, neither are your ways my ways, saith the Lord. For as the heavens are higher than the earth, so are my ways higher than your ways" (Isa. lv. 8-9). In short, as we cannot accurately comprehend His essence, and yet we know that His existence is most perfect, free from all admixture of deficiency, change, or passiveness, so we have no correct notion of His knowledge, because it is nothing but His essence, and yet we are convinced that He does not at one time obtain knowledge which He had not before; i.e., He obtains no new knowledge, He does not increase it, and it is not finite; nothing of all existing things escapes His knowledge, but their nature is not changed thereby; that which is possible remains possible. Every argument that seems to contradict any of these statements is founded on the nature of our knowledge, that has only the name in common with God's knowledge. The same applies to the term intention; it is homonymously employed to designate our intention towards a certain thing, and the intention of God. The term "management" (Providence) is likewise homonymously used of our management of a certain thing, and of God's management. In fact management, knowledge, and intention are not the same when ascribed to us and when ascribed to God. When these three terms are taken in both cases in the same sense, great difficulties must arise: but
when it is noticed that there is a great difference whether a thing is predicated of God or of us, the truth will become clear. The difference between that which is ascribed to God and that which is ascribed to man is expressed in the words above mentioned, "And your ways are not my ways."