God’s necessary existence is something that needs to be explained. Otherwise we are stuck with a brute necessity within our theistic ultimate explanation of reality. A promising explanation of God’s necessary existence is as follows: God exists necessarily, because perfection logically entails existence. If we consider the concept of God, we realise that God must exist in reality. God is thus, in a sense, the opposite of a married bachelor (who necessarily does not exist in reality).

However, Richard Swinburne has argued that God’s existence is not logically necessary. Herman Philipse outlines Swinburne’s case in his boek God in the Age of Science? Philipse does not consider all of Swinburne’s arguments persuasive, but he does think that some of them are convincing, including the following argument:

“Fortunately, however, Swinburne also provides convincing arguments for his claim that the proposition ‘God exists’ is not logically necessary. He says, for example, that if this proposition were logically necessary, all propositions entailed by it would also be logically necessary. But a proposition such as ‘it is not the case that no one knows everything about the past’, though entailed by ‘God exists’, clearly is not logically necessary. For we may safely assume that its negation, ‘nobody knows everything about the past’, does not contain any concealed contradiction.” Philipse, God in the Age of Science?, p. 123.

Let us consider this argument carefully. Let p be the proposition that God exists and q the proposition that no one knows everything about the past. If p is necessarily true, then q is necessarily false. But q by itself is not necessarily false, that is, its necessary falsity is a consequence of p and not due to a contradiction internal to q. At least, that appears to be the case. But the phrase ‘no one’ in q is problematic. For there is a clear contradiction in the following sentence: Set 1 includes an all-knowing person and no one in set 1 is all-knowing. In other words, we need clarity about who is included in ‘no one’, before we can see clearly whether or not there is a contradiction in q.

Thus, a better version of q is as follows: There isn’t a person who knows everything about the past. If p is necessarily true, then q is necessarily false. But q is not necessarily false by itself (i.e. because of an internal contradiction). Does this then prove that p is not true by logical necessity? I struggle to see why. After all, q is necessarily false by necessary logical consequence. Why is that not enough? Perhaps I fail to understand the argument, but, in my view, it is also not a persuasive argument against the thesis that God’s necessarily existence is due to logical necessity.