Alvin Plantinga has responded to Robert Adams's formulation of the grounding objection in the following way:
To investigate this question properly, we should have to investigate the implied suggestion that if a proposition is true, then something grounds its truth, or causes it to be true, or makes it true. Is this supposed to hold for all propositions? What sorts of things are to be thought of as grounding a proposition, and what is it for a proposition to be grounded by such a thing? What grounds the truth of such a proposition as this piece of chalk is three inches long? I don't have the space to enter this topic ; let me just record that the answers to these questions aren't at all clear. It seems to me much clearer that some counterfactuals of freedom are at least possibly true than that the truth of propositions must, in general, be grounded in this way. (p. 52)
Plantinga always does this; one might call it Argument by Way of Wide-Eyed Innocence: if he doesn't want to accept a claim C, he doesn't argue against it, but just says that C isn't clear, and that some other claim with which C is supposed to conflict is much clearer to him than C is. We could also call it Passive-Aggressive Refutation. It can sometimes be fun, e.g., when he does it against people who have a long history of doing the same thing (atheists, for instance). But it is, in the end, not constructive. And if it is not taken to be merely the beginning of an argument rather than a real refutation, it is mere obscurantism. There is, in fact, no mystery here. When we say a given statement is true or false, 'true' or 'false' is functioning as what would have once been called an extrinsic denomination. Truth and falsity are not in the statement as such; they are applied to the statement in virtue of something else (I am setting aside a few cases like self-referential statements). What makes a statement true is the actual state of affairs in virtue of which the statement is true (in other words, contrary to Plantinga there is no mystery here: what is meant is just what is said). What makes 'This is a three-inch piece of chalk true' is this chalk's actually being three inches. To say otherwise is to deny that we can say a statement is true.
The grounding objection (in effect) emphasizes the word 'actual'. It's easy enough to see what the actual state of affairs making 'This is a three-inch piece of chalk' true. It gets a little more complicated in other cases. Consider:
(A) The sun will rise tomorrow.
What makes this true (assuming and hoping that it is, and assuming that it is causally necessary) is that there is some actual set of causes which are such that the sun will rise tomorrow. In other words, something actually exists in virtue of which we can legitimately say that (A) is determinately true. Likewise, since the situation described in (A) will (we are presuming) actually happen, that situation also makes (A) true. (The fact that (A) is made true both by its causes and by the situation to which it refers has been known for centuries; as the medievals might have said, it is possible to know something to be true in its causes or in itself.)1
When free choice enters into the picture, however, things get a bit more narrow. For instance (assuming the following to be still in the future, and assuming that Peter freely does it):
(B) Peter will deny Jesus.
This is made true by Peter denying Jesus in the future. In other words, it can be true in itself. Can it be true in its causes? Not if we take free choice seriously. Free choice doesn't determine the effect to one, so the cause in this case (Peter, as a free agent) only makes true a set of statements about what could happen -- namely, statements indicating the things that Peter could choose. Probabilities can be added (as Adams tends to do). Thus
(C) Peter will probably deny Jesus
can also be true, given the cause involved. (Although (C) is, interestingly, not made true in itself by Peter's denying Jesus in the future, but by Peter's being such now that he will probably deny Jesus. But this, while interesting, doesn't have any bearing on the point, since the cause is still the same.)
Now we come to counterfactuals of freedom. And here we must be careful in a way that people sometimes are not. Some counterfactuals of freedom can clearly be known in their causes. For instance,
(D) If God makes Peter to persevere, Peter will not deny Jesus.
The freedom here is in the antecedent. The problem doesn't arise in such cases, because then we are only considering the causal powers of the free agent, and those causal powers ground the truth of the statement. In the case of (D), it's God's ability to make Peter persevere; (D) is really a statement about what God can do. Many counterfactuals about free agents are of this sort. They are not the problem. For one thing, they aren't a matter for middle knowledge; they are a matter for natural knowledge. For another, what grounds their truth is fairly clear.
The problem tends to arise when the statement is counterfactual and the freedom is in the consequent. For instance:
(E) If Curley had been offered a bribe of $35,000, he would have freely accepted it.
The consequent can't be known to be true in virtue of its actually happening, because it doesn't. Nor can it be known in its causes; if Curley had been offered a bribe of $35,000, he might not have freely accepted it, and this problematizes the truth of (E). Nothing actually exists or occurs in virtue of which it could be known by anyone that Curley would have freely accepted it; Curley never, in fact, was faced with such a choice, and as a free agent, there was always a possibility of his going either way. Compatibilists could deny this, but Molinists are libertarians about free will. That is, in fact, a big reason for accepting middle knowledge: if sense can be made of it, it provides a way to have both libertarian freedom and divine sovereignty. That, anyway, is the promise.
According to Plantinga, "what grounds the truth of the counterfactual, we may say, is jus that in fact Curley is such that if he had been offered a $35,000 bribe, he would have freely taken it" (p. 53). But notice what Plantinga is effectively saying here: he is saying that what makes the statement true is the cause, Curley as a free agent. But given that we are assuming libertarian free will, there is nothing actually in the cause that makes the statement true. Ex hypothesi, Curley is not such that there is one determinate thing that would have happened; he is only such that that thing could have happened. At most, he is such that that thing would almost certainly have happened -- but 'almost certainly' is not enough to get middle knowledge off the ground. Plantinga considers another sort of case:
(F) If Adam and Eve had not sinned, God would not have punished them.
Says Plantinga, it's surely possible that it's true. In virtue of what is it possible that it's true? In other words, why would we say that it's possible that it's true? Well, because what we know of God is such that it would be impossible for him to punish an innocent: (F) falls under natural knowledge, not middle knowledge. It is more like (D) than (E).
A more interesting case is given by Freddoso:
(G) Even if Adam and Eve had not sinned, God would have become incarnate.
As Freddoso notes, a lot theologically hangs on whether this is true or not, and historically it has been an important theological debate. But we have to ask the same question. And when we look at the debate, we find that (for Scotus, for instance), (G) is actually just a way of talking about the ordering of God's purposes. So (G)'s truth depends on the suppositions (1) that Scotus is right about the ordering of God's purposes in becoming incarnate; and (2) that if Adam and Eve had not sinned, God would have kept the same ordering of purposes. Let's just grant (1) to simplify the discussion. (2) yet again makes (G) more like (D) than like (E); (G) is simply about the actually nature of the cause given supposition (2).
This might look suspicious, but it's actually very common. You don't even need to go to counterfactuals of freedom to find similar instances. Consider the following:
(H) If we have peanut butter, we can make peanut butter and jelly sandwiches.
(H) is straightforwardly true if we grant background information, e.g., that we have jelly, that we have bread, that we have the physical ability to make sandwiches, etc. Without these we could have all the peanut butter we could want, and never could we make a single peanut butter and jelly sandwich. Likewise with (G): if (2) is supposed to be false, whether God would become incarnate would depend on whatever reasons for acting a certain way that God would have had instead. There are only two ways anyone, even God, could know what reasons for acting a certain way God would have had instead: (1) if they are somehow necessary, in which case God would know them by natural knowledge; (2) if God resolved that if (2) weren't true He would have those reasons, in which case God would know them by free knowledge. Appeal to middle knowledge fails to do justice to divine free agency; God is so free that there is no determinate truth about what other reasons He would have had, because He could have had any number of reasons for action. There is no one thing; and therefore a statement saying God would have done one thing can only be true on suppositions that narrow down the field of God's freedom to one thing.
So why would one be interested in (G)? The answer is obvious, because one only has to look at why the scholastics were interested in (G) in the first place: the background suppositions are such that (G) is really about why God actually became incarnate; Scotus's discussion would not be the least bit less interesting if we suppose that (G) were literally false, because the discussion is not about (G). (G) is just one way to talk about God's actual doings. And again, we don't have to look far to see that many, many counterfactuals function in this way: it is irrelevant whether we regard them as actually true. What is relevant is that, given the right background suppositions, counterfactuals are often indirect ways of talking about the actual abilities of agents. It may be put counterfactually as a convenient verbal shorthand, but it means something about the actual state of affairs. The failure to recognize this as a possibility undergirds many Molinist arguments.2
Take that, Molinists.
Page numbers are from
Hasker, Basinger, and Dekker, eds. Middle Knowledge: Theory and Application Peter Lang (New York, 2000).
1 The fact that we have to consider both the thing in itself and the thing in its causes in 'futuribles' is why the parallel Freddoso suggests between antirealists about the future and antirealists about certain counterfactuals of freedom (pp. 29-33) doesn't work: it assumes that nothing but the causes make a statement true. This need not be assumed, and, in fact, most people don't assume it. Indeed, no one who accepts divine knowledge of vision (including traditional Molinists!) assume it. So anti-realism about the future is simply a red herring.
2 Richard Gaskin has a bizarre argument in which he claims that if counterfactuals of freedom are not true, God could not know what anyone would do in a given possible world (p. 144). But this is utterly absurd; a given possible world is simply one world-history that could happen, not necessarily what would happen. So talking about what a person 'would do in a possible world' is just a very roundabout way of saying what a person could do. And this is known not by middle knowledge but by natural knowledge. Such sophistry does explain why Molinists have always been so addicted to talking about 'orders of nature', 'possible worlds', and the like. Gaskin's argument also overlooks the fact that most non-Molinists do not have a Molinist conception of a possible world as something that in some way actually exists for God to review; non-Molinists collapse possible worlds to natural knowledge. Molinists themselves actually have to allow that possible worlds are in some way known by natural knowledge, since that's a necessary condition of God's knowing His power; they want to go further and say that there is an additional sort of knowledge of possible worlds beyond that. No one else agrees.