Calvinists often argue that defending man as possessing libertarian free will (giving man a true choice between walking with God or not walking with Him and therefore the outcomes being conditional) not only places man’s salvation in his own hands, but it also creates uncertainties that would mean that God would not know everything since (as the argument goes) one cannot know an uncertainty for certain. On the other hand, the Calvinist idea is that all actions are predetermined by God either through decrees, compatibilism, or both and this makes everything certain and therefore knowable. This understanding makes the theological reality of libertarian free will an impossibility in Calvinism. Fortunately, the impossibility is merely a Calvinistic impossibility rather than an actual one.
William G.T. Shedd said regarding undecreed voluntary acts of humans, “Whether they shall occur rests ultimately upon man’s decision, not upon God’s. Hence human volitions are uncertainties for God, in the same way that an event which does not depend upon a man’s decision is an uncertainty for him.” (italics added) Note that man’s inability to know what another free being will choose (if otherwise choice exists) is attributed to God. Such an application seems self-evidently unacceptable.
I would make the following distinctions. Man knows differently from God since man is not omniscient and did not originate his ability to know or choose. God created man with such ability (always knowing he would have such, which man did not know), and He omnisciently always knew how such endowment could and would be used, which man did not nor does he now know. God’s knowledge is particular, comprehensive, exhaustive, and eternal. Man knows and learns perceptively whereas God knows because He is essentially omniscient. That is to say, God as God knows everything as an essential part of who He is (even free acts of libertarian freedom), and therefore, does not look beyond Himself for knowledge, i.e. learn perceptively. He does not look down the halls of history to know contingencies, He knows them essentially; conversely, man’s knowledge is not of any such caliber either prior to or subsequent to the choices of others or even his own decisions.
Shedd argues that the undecreed (anything contingent) cannot be known, saying, “So long as anything remains undecreed, it is contingent and fortuitous. It may or may not happen. In this state of things, there cannot be knowledge of any kind.” He further summarizes the impossibility of such a state, “To know, or to foreknow an uncertainty, is a solecism [inconsistency or error].”  He continues to pose decrees as certain and man having otherwise choice as being contingent and uncertain, which means according to him, “There is, therefore, nothing knowable in the case. To know, or foreknow an uncertainty, is to know or foreknow a non-entity.”
Succinctly, he is arguing that contingency is an uncertainty and therefore nothing; for that reason, it cannot be known, and it certainly cannot be known certainly. This understanding leads to the conclusion that for man to have the freedom to choose other than what was predetermined is impossible because such reality undermines God’s sovereignty. Charles Hodge states, “Because all events are included under the categories of the actual and possible; and, therefore, there is no room for such a class as events conditionally future. It is only possible, and not certain, how men would act under certain conditions, if their conduct be not predetermined, either by the purpose of God, or by their own decisions already formed.” As Hodge discusses the subject, he makes it clear that Extensivists (non-Calvinists) are the ones who accept what is now termed Libertarian free will and Calvinists are Compatibilists.
This emphasis upon determinism stresses Calvinism’s inability to perceive God as portrayed in Scripture. It seems to me, while neither side is heretical, our views of man emanate from our different views of God. The Scripture seems to portray God as more than capable of creating man with such freedom, restoring it after the fall, and still having always known everything man would do. God is all-powerful and all-knowing. This includes the actual, potential, counterfactuals of otherwise choice (contingencies), what He will and will not cause, permit, and what He will make conditional even to the point of what option man will choose within the range He permits; He further knows what options flow from that and what man will subsequently choose out of that contingent range of options (new reality or sequence of events for man).
He knows our present and future thoughts, and He has known such eternally. His understanding is infinite. (Ps. 94:9; Ps. 139:1—18; Ps 147:5; Proverbs 15:3; Proverbs 15:11; Ezekiel 6:5; Matthew 10:30; John 2:24—25; Acts 15:18; Hebrews 4:13). It is true that Calvinists believe these verses, as well as the surety and infinitude of God’s knowledge, but they do so for very different reasons than Extensivists; this difference includes the nature and role of causality and even what is meant by “know.” Calvinists postulate that He knows all because He causes all, decretal theology, compatibilism, etc.—which causation may include determined secondary causes.
The following provide some examples of God’s conditional knowledge (counterfactual knowledge). This can be seen in Matthew 11:20—24. This passage gives every appearance of teaching that had the people of Tyre, Sidon, and Sodom had the opportunity afforded Bethsaida, Chorazin, and Capernaum, they would have repented; thus the judgement upon the cities Jesus was addressing would be more severe. Charles Hodge, who seems troubled by this clear meaning, seeks to make this passage nothing more than “a figurative mode of stating the fact that the men of his generation were more hardened than the inhabitants of those ancient cities.” However, read without theological importations, it seems clear that Jesus was truly excoriating the people of these contemporary cities for squandering what others would have embraced. He could make such a claim based upon His omniscience, which includes counterfactual knowledge (what if). Jesus says clearly, “they would have repented.” D.A. Carson says in reference to this judge (Jesus), “The Judge has contingent knowledge: he knows what Tyre and Sidon would have done under such-and-such circumstances.”
Charles Hodge says regarding God as the sum of perfection, “Such a being cannot be ignorant of anything; his knowledge can neither be increased nor diminished.” On this we can all agree. A difference that Extensivists have with determinists is that we would argue that there is nothing that would or could happen by either particular predetermination (which includes unconditional realities) or predetermined permission (which includes conditional eventualities) of which God has ever lacked infinite knowledge. To wit, uncertainties in time and space and the mind and experience of man were never uncertain in the mind of God. Equating uncertainties of man to uncertainties of God, and in so doing making contingencies essentially nothing and consequently unknowable, is neither reflective of Scripture nor essential omniscience.
God’s knowledge not only includes the significant counterfactual potentialities, but it even includes the mundane such as knowing every bird that falls from the sky and the number of hairs on everyone’s head (Matthew 10:29—30). Both states are ever changing and rather unimportant, and yet God has eternally known everything about all of them because He is essentially omniscient; such neither entails nor even suggests that He micro-causally predetermined each changing state.
The Bible portrays many things as contingent, such as wisdom being conditioned upon seeking and asking (Proverbs 2:1—12; 4:5—7; 6:16; James 1:5). He grants grace to the ones who choose humility over pride (1 Peter 5:5). This genre of conditionality as well as the voluminous passages regarding the promise of blessing or cursing as contingent upon the decision of man (Genesis 2:16—17; Deuteronomy 11:26—28) as well as salvation being contingent upon the choice of man and judgement upon same (Romans 10:8—11); all of which gives every indication of otherwise choice.
Part Two Coming Soon!
 I say theological because Calvinist and non-Calvinist alike know that no one lives consistently with determinism; accordingly, Libertarian freedom is obviously a real-world reality.
 William G.T. Shedd, Dogmatic Theology, vol. I (Nashville: Thomas Nelson Publishers, 1980), 397.
 Shedd Dogmatic Theology, vol. I, 397. He is comparing Socinian and Arminian theology.
 Shedd Dogmatic Theology, vol. I, 398. Solecism meaning an inconsistency or error.
 Shedd Dogmatic Theology, vol. I, 398.
 Charles Hodge, Systematic Theology, vol. I (Grand Rapids, MI: Wm. B. Eerdmans Publishing Company, 1986), 399.
 He later refers to this concept variously as “contingency” “liberty of indifference” “self-determining power of the will,” although I do not find his definition to be accurate or precise. Charles Hodge, Systematic Theology, vol. 2 (Oak Harbor, WA: Logos Research Systems, Inc., 1997), 282—283.
 Hodge says, “This is one of the points in which theology and psychology come into immediate contact. There is a theory of free agency with which the doctrines of original sin and of efficacious grace are utterly irreconcilable, and there is another theory with which those doctrines are perfectly consistent. In all ages of the Church, therefore, those who have adopted the former of these theories, reject those doctrines; and, on the other hand, those who are constrained to believe those doctrines, are no less constrained to adopt the other and congenial theory of free agency. Pelagians, Semi-Pelagians, and Remonstrants are not more notoriously at variance with Augustinians, Lutherans, and Calvinists, on the doctrines of sin and grace, than they are on the metaphysical and moral question of human liberty.” Charles Hodge, Systematic Theology, vol. 2 (Oak Harbor, WA: Logos Research Systems, Inc., 1997), 278.
 Hodge, Systematic Theology, vol. I, 400.
 D.A. Carson, The Expositor’s Bible Commentary on Matthew, vol. 8 (Grand Rapids, MI: Zondervan Publishing House, 1984), 273. D.A. Carson is a Calvinist, but he is forthright about the simple meaning of the passage, which I appreciate. As a Calvinist, if consistent, he would have difficulty with this statement and unconditional election. The non-Calvinist has no such problem since we teach that everyone gets an opportunity, but we do not teach that everyone gets the same opportunity to believe, which seems to be an absolute impossibility in a time and space continuum.
 Hodge, Systematic Theology, vol. I, 397.