Cracking Concrete: The Grounding Objection Refuted
By far the most common objection to middle knowledge is what theologians and philosophers call the grounding objection. The objection posits counterfactuals have nothing grounding their truth-value.
This objection relies on is a specific theory of truth called correspondence theory and specifically truth-makers. This is to say, these counterfactuals have nothing concrete to base their truth in and as such they must not contain truth-value at all. For instance, if I state the proposition, “The light is red,” the proposition is only true if and only if the light is actually red—the red light itself is the truth-maker. At first blush, this may appear to be a causal relationship but it would be absurd to posit that the truth-maker makes the proposition describing it true. For instance negative propositions such as “the flying spaghetti monster does not exist” is certainly true, but there is no truth-maker available for the proposition. Therefore, the relation between the truth-maker and truth-bearer (proposition describing the truth-maker) is not a causal one for the reason that the existence or non-existence of a thing does not cause a proposition to be true. If this is true then the relationship between a truth-maker and truth-bearer must be logical instead. This is a point all too often missed by anti-Molinists.
Gregory Boyd thinks it is a causal relationship:
The issue is this: What grounds, or makes true, the eternal “would” counterfactuals that comprise God’s middle knowledge. It cannot be God’s will that grounds the eternal truth-value of ‘would’ counterfactuals, for classical Molinism grants that this would undermine libertarian freedom. But neither can it be the libertarian free agents themselves, since these agents exist only as possibilities when God knows them in his pre-creational middle knowledge. In fact, it cannot even be the future actions of free agents, since all but one of the innumerable possible worlds including free agents never exist. Hence, to embrace classical Molinism, one must accept that the facts about what every conceivable free agent would do in every conceivable circumstance simply exist, from all eternity, as an ungrounded, metaphysical surd.
To understand how radical a claim this is one needs to understand that counterfactuals are used daily by individuals in determining decisions. “If I were to fly to Kansas instead of driving, it would save me 14 hours,” is a counterfactual statement. “If I were to jump out of the aircraft without a parachute, I would die upon impact,” is another counterfactual. Propositions like these are crucial to decision making. Is the objector of middle knowledge ready to defend that these propositions do not have truth-value on the basis that their state of affairs does not exist?
There are many statements which contain truth-value, yet do not contain descriptions of concrete objects.
- Pteranodons are extinct.
- Killing innocent civilians is wrong.
- A Dyson Sphere encompasses a star.
In the first statement, Pteranodons are now extinct and are not a concrete object, yet we still consider this to be a true statement, thus it cannot have a concrete truth-maker. The second statement reports an ethical judgment that does not imply the existence of actual civilians that were killed. The third statement describes a theoretical object and has no concrete object for its truth-maker either.
It seems to me that if statements like those in the above can be true, without concrete truth-makers, then counterfactual statements can be true as well. If counterfactual statements need to be grounded, then anti-Molinists owe us an explication as these other statements do not have concrete truth-makers and yet are still considered to have truth-value..
I think it may be the case that if counterfactuals do require truth-makers, they could be the propositions or statements themselves. Thus, what makes the statement, “If I were to fly to Kansas instead of driving, it would save me 14 hours” is the fact that if I were to fly to Kansas instead of driving, it would save me 14 hours” If statements such as “Pteranodons are extinct” can have truth-value as well as other past and future-tensed statements, it seems to me that counterfactuals can as well. The anti-Molinist still has a great deal of work ahead if he wants to hold to the grounding objection. At this point, myself and many other Molinists are unconvinced this objection holds water. 
 Stanley N. Gundry and Dennis W. Jowers, eds., Four Views on Divine Providence (Grand Rapids: Zondervan, 2011), 131.