Webster's Dictionary defines "knowledge" as: the circumstance or condition of apprehending truth or fact through reasoning : the fact or condition of having information or of being learned a: the sum of what is known.The key words in this definition is "truth or fact through reasoning". Open Theist apply this same definition to God's ability to know something or his omniscience. Again, when God tells us he has "knowledge" of something He must use the same definition or understanding as mankind. If not, then how can we ever make any sense of what God is trying to convey to us in His Word or when he speaks to us? Remember, words have meaning and when God uses a word it must have the same definition as we would interpret! In other words, we believe God interacts or communicates with His created beings by using reason and logic. Therefore in order for something to be "known" by God it must be "knowable", it must be factual or it must truly exist.
We use this definition "to know" or "knowledge" in our everyday lives. For example, let's say that someone walks up to you and begins to inform you that they "know" karate. From the definition of the word "know" we would be able to surmise that the statement just made by this person is that they have some level of "knowledge" or experience in the field of martial arts. Their knowledge came as a result of factual information (truths) that fully exists in reality. This same person, who "knows" karate, has obtain this particular "knowledge", that is a set facts, through the use of his or hers reason and logic. In other words, the information known by this person must first be real or actual.
If you deny this, then you deny the very definition of what it means to "know" something or to have knowledge. For example, if on the other hand another person were to walk up to you who claimed to have been from the planet Mars and knows Martian Martial Arts - you would immediately consider this person to be (a.) insane or (b.) a comedian. The reason you would consider this person insane is that we have facts (truths) that mankind has never physically been to Mars and from what we do know about Mars is that it is uninhabitable planet - therefore by using logic & reason we are able to deduce that the information this person is claiming to "know" - is indeed false. It is not knowable, it does not exist, it has not occurred in reality and is not factual. So as it pertains to God's Omniscience, Open Theist would say matters pertaining to the future of free-will beings God knows only that which is knowable. Therefore since the future has not yet occurred and does not yet exist in reality it is then "open". However, by denying God knows the future free will choices of man, it is not assumed that God doesn't know certain future events. This is often a claim laid against Open Theist that is not at all true. This we will address further in my next posting.