Good point.
Causality is an instance of
logical necessity but
determinism is not. I will explain below.
I am wondering when someone will bring up the kind of argument that Donald MacKay, who was a professor of biophysics at Keele U. in England, made in the 20th century. Define "free will" in a certain precise sense, namely, that there cannot exist a physically deterministic prediction about what a choosing agent - call him
Joe - will choose to do in the future that if disclosed to him, he would be both correct to believe and incorrect to disbelieve the prediction. The argument hinges on self-referencing logic because something Joe will do in the future affects him, the person about whom the prediction is made. I have a somewhat altered form of it
here. A more casual (not causal!) explanation of it is as follows.
The Logic of Free Will
The common difficulty in reconciling
divine sovereignty, whether attributed to God or Nature, and human freedom of the will, is caused by the kind of logic employed in attempting to understand their relationship. We are acculturated to think in the logic of Western tradition, the propositional logic of Aristotle. This is generally quite beneficial, for it gives our thinking a formal framework of coherency. However, it has been understood for centuries that our familiar logic has its limits in helping us understand paradoxical concepts.
It is paradox, or more precisely,
antinomy, that reveals limits to logic including scientific arguments. The Apostle Paul referred to an antinomy, a statement of a Cretan (Titus 1:12): Cretans are all liars, etc. Of course, “all Cretans” includes the Cretan who uttered the statement. Consequently, the statement must be false. But if it is not true, then Epimenides (the most likely Cretan to have said this) might have told the truth. Yet, if true, then the statement could not be true. Antinomies go around in logical circles like this and logicians consider them “logically indeterminate.” Their truth-value (true or false) cannot be determined. Logical indeterminacy appears in the understanding of the relationship between God’s sovereignty or Nature's determinacy and our free will.
In deference to those who have an unwillingness to accept God’s sovereignty as
deterministic (that is, as determining all things, even the fall of dice), the weaker idea, that God-in-time can only foresee but not determine the future with absolute accuracy is a sufficient starting point. So let’s start with God, or for atheists reading this, some super-scientist who merely
knows the future deterministically but does not determine it. (Such a view of God makes it difficult to know whether God or Nature is in charge of the universe. But that is another matter.) Furthermore, let us assume human freedom of choice, and in particular for Joe. God-in-time can then predict the outcome of future events involving choices Joe will make – for example, whether he will read this message, or accept the gospel or not. God watches and waits, and his predictions come true every time. The predictive performance is perfect.
Now, what would be the logical status of these predictions if he were to offer them to Joe? Is Joe bound by their predictive truth to believe them? If this deterministically true yet undisclosed knowledge of God were to be revealed to Joe, would Joe be mistaken to believe otherwise?
If Joe’s
freedom of choice is understood in the specific sense that there cannot exist a prediction of Joe’s choice that would be unconditionally true for Joe, then the answer is
no;
there cannot exist a prediction about Joe which he would be both correct to believe and incorrect to disbelieve, if only he knew it. Let’s see why this is so.
If Joe is offered the prediction about a choice he will make, and he believes it, then the “Joe” who believes it is not the “Joe” described by the prediction. In offering the prediction to Joe, it changes Joe so that he is no longer the “Joe” of the prediction. The prediction does not take into account one of the critical factors about Joe, namely, his believing the prediction.
But God or a super-scientist can also take into account the effect that the prediction will have on Joe. Suppose further that God modifies the prediction to take into account Joe’s believing it. That way, when Joe believes it, the prediction remains valid. Joe’s believing it has been taken into account in it. But in this case, Joe would not be incorrect to disbelieve the prediction, because a “Joe” who does not believe it is also not the believing Joe described in it. For either prediction, whether the prediction is true or not depends on whether Joe believes it or not. Whether a given true undisclosed deterministic prediction is true or not is up to Joe.
In disclosing the prediction to Joe, God has interacted (“interfered”) with Joe, causing the otherwise true prediction to be “out of date” due to the interaction. God-in-time, in interaction with us, also participates in the logical indeterminacy that underlies Joe’s free choice. But only a God whose secret knowledge of all history is not disclosed to Joe, can know with certainty Joe’s choices. And Joe can know them, but only by knowing his own choices.
The scriptures present us with the curious fact that both “views” of God are needed to express his full “dimensionality.” It is not difficult to extend the above argument to allow for God-in-"eternity" (the Father, perhaps) to be the predestinarian of Calvinism, who causes all events by the counsel of his will, while also allowing for God-in-time (the Son, perhaps) in the incarnation, God who is closer to us than hands and feet. The scriptures describe the Son as the one who is in dialog with us, who is the mediator between us and the Father, through the Spirit. Even Christ claimed not to know the future, but only the Father knows, he said.
To fail to distinguish between God-in-time and God-in-"eternity" leads to the confused situation that I detect in the discussion in this thread. Even God cannot disclose to us foreknowledge of our choices that we would be both correct to believe and mistaken to disbelieve. It is simply a logical fact (though by a higher-order logic than that of Aristotle) that we can be free and God be sovereign.
Note that the above argument
assumes free will and proceeds to show that it is not negated by physical determinism. It is a reasonable assumption because we live our lives on the basis of that assumption, and might wonder whether our scientific understanding of ourselves, based on physical causality, negates it. Causality that is deterministic only applies to open-loop systems, but once there is feedback, such as giving the prediction to Joe beforehand, brings in a different kind of logic that applies to such physical "systems" such as Joe. A certain level of self-awareness changes the whole discussion of determinism and free will of self-aware beings.
A
dual kind of argument that assumes physical determinism and argues to a logical position of
semi-decidability is given in my version of this argumentation about self-referencing logic in the
above link.
This kind of self-referencing logic appears also in computer software - usually of the AI kind - and one must then ask if physical determinism applies to software. The discussion of determinism and free will is thus shifted up a gear or two!
