Consider the following scenario, in order to see how Middle Knowledge impacts the understanding of divine omniscience from both the Calvinist and Arminian perspectives.
Dave Hunt explains: “God knows every thought, word, and deed beforehand because He is omniscient. That God foreknows all that will happen doesn’t cause it to happen, because He exists outside of time.” (Debating Calvinism, pp.165-166, emphasis mine)
One member of The Society of Evangelical Arminians states: “God created time; therefore, He can stand outside His creation and/or enter it at anytime that He desires (hence the incarnation). For me, a finite man, it is difficult to understand what God knows.” (SEA, emphasis mine)
Jerry Vines explains: “God’s knowledge of the future doesn’t determine the future any more than man’s knowledge of the past determines the past.” (Calvinism – A Baptist and his election, emphasis mine)
If God is independent of time, then He is free to know any point of time. In other words, if God is independent of time, then He can know His own future self-determined choices, as well as the future self-determined choices of “Bob.” God can then relay that information back to someone in our present day, and state it prophetically and accurately. Such information would be infallible, because God is there, witnessing it and interacting with it.
Calvinist, R.C. Sproul, states: “God’s omniscience refers to God’s total knowledge of all things actual and potential. God knows not only all that is, but everything that possibly could be.” (What is Reformed Theology?, p171, emphasis mine)
Sproul adds: “He knows all things will happen because he ordains everything that does happen. This is crucial to our understanding of God’s omniscience. He does not know what will happen by virtue of exceedingly good guesswork about future events. He knows it with certainty because he has decreed it.” (What Is Reformed Theology, p.172, emphasis mine)
Calvinist, Steve Hays, explains: “The future is known to God because it has been determined by the decree of His free will. … In the eternal decree, all that comes to pass has been foreordained. There is no place for chance or indeterminacy in the system of reality. … God determined, by the free decree of His sovereign will, which of the possible worlds should be actualized. ... God freely chose to bring about this world rather than any of the other infinite possibilities.” (My predestination is all freewill)
According to Calvinism, God knows all things actual because God has determined all things actual. If God knows all things potential in the same way, that is, by determining all things potential, then the question arises as to how God would determine all things potential. In other words, if all things potential is an infinite thing, then determining all things potential is like determining infinity, which is logically as impossible as determining the highest number, as there is always one number that is higher. So the Calvinist explanation of determining all things potential, becomes quite challenging. So, alternatively, does the Arminian model provide a means that works? For starters, God wouldn’t need to determine anything at all. Thus for God to know something potential, simply requires that God know something that “Bob” would self-determine to do. Set to the occurrence at Jeremiah 38:17-24, God’s knowledge of what the people involved would do is based upon His knowledge of them, and their self-determinations, rather than God’s self-determinations, and hence the Arminian perspective has a decisive advantage over the Calvinist model.
One member of the Society of Evangelical Arminians explains: “A counterfactual in Calvinism is like a fantasy island which ponders all that was never desired to be decreed.” (SEA)
From the Calvinist perspective, God would know all things possible, to the extent that it would exist by virtue of that which was decreed. However, the challenge remains that it nonetheless denies true omniscience if God can only infallibly know what He decrees or what is related to His decrees.