Does God’s foreknowledge of the future cause it to be fixed?
For example, if God already knows what a person will do in the future, how can they make a decision other than what God knows will happen?
And if they are able to make a decision other than what God knows, wouldn’t that falsify God’s knowledge of the future events?
If you mean foreknowledge in the sense of infallible foreknowledge then the answer is yes, it does mean that the future is fixed. Whether the foreknowledge is the cause of it being fixed is another question, but if God infallibly knows what you will do tomorrow then when you do it, you do not do so freely because in order to choose there must be alternatives and if God's foreknowledge is infallible then you action is logically necessary.
Here's the logical proof...
T = You answer the telephone tomorrow at 9 am
- Yesterday God infallibly believed T. [Supposition of infallible foreknowledge]
- If E occurred in the past, it is now-necessary that E occurred then. [Principle of the Necessity of the Past]
- It is now-necessary that yesterday God believed T. [1, 2]
- Necessarily, if yesterday God believed T, then T. [Definition of “infallibility”]
- If p is now-necessary, and necessarily (p → q), then q is now-necessary. [Transfer of Necessity Principle]
- So it is now-necessary that T. [3,4,5]
- If it is now-necessary that T, then you cannot do otherwise than answer the telephone tomorrow at 9 am. [Definition of “necessary”]
- Therefore, you cannot do otherwise than answer the telephone tomorrow at 9 am. [6, 7]
- If you cannot do otherwise when you do an act, you do not act freely. [Principle of Alternate Possibilities]
- Therefore, when you answer the telephone tomorrow at 9 am, you will not do it freely. [8, 9]
Source
So, it really comes down to what we mean when we talk about foreknowledge. When we say that Jesus knew that Peter would deny Him three times, do we mean that Jesus just expected it with high confidence or do we mean it in a more absolute way? Is it more like a well-informed prediction or is it absolutely firm, infallible knowledge. The former allows for free will, the later does not.
There is one other issue here that has to do with the consequences of past actions. It could be that there are situations that, because of one's past freely chosen actions, a person could find themselves in a situation where they are quite trapped and have no alternative but to act in a particular manner. In such cases, God could certainly have infallible foreknowledge of what the person will do without there being any issue concerning free will because it is the person's own past actions that have steered him into a situation where he has no alternatives.
