Leibniz's Theodicy consists of two parts, the first on faith and reason, the second on the freedom of man in the origin of evil. I am trying to understand paragraph #37 (p. 144 of the Huggard translation):
. . it follows not that what is foreseen is necessary, for necessary truth is that whereof the contrary is impossible or implies contradiction. Now this truth which states that I shall write tomorrow is not of that nature, it is not necessary. Yet supposing that God foresees it, it is necessary that it come to pass; that is, the consequence is necessary, namely, that it exist, since it has been foreseen; for God is infallible. This is what is termed a hypothetical necessity. But our concern is not this necessity: it is an absolute necessity that is required, to be able to say that an action is necessary, that it is not contingent, that it is not the effect of a free choice.
1. Necessarily (if God foreknows that P, then P is true).
We note that the necessity in (1) attaches to the conditional, not to its consequent. This is a case, then, of necessitas consequentiae, not of necessitas consequentiis. In Leibniz's jargon, (1) is a case of hypothetical necessity as opposed to absolute necessity. The consequence is necessary, not the consequent. From (1) one cannot infer
2. If God foreknows that P, then necessarily P is true.
So far, so good. If a proposition is known, by God or by anyone, then it must be true; but that is consistent with saying that the proposition known is contingently true. Given that I know that I am blogging, then I must be blogging; but that is not to say that I am necessarily blogging: I might not have been blogging now.
What I don't understand, though, is the last sentence in the passage quoted. The last sentence strikes me as false. Leibniz seems not to appreciate that if a contingent state of affairs is necessitated by something other than the agent, then there is a prima facie difficulty about reconciling it with freedom of choice. The source of necessitation might be divine foreknowledge (theological fatalism), or the laws of logic (logical fatalism), or the past and the laws of nature (causal determinism). No matter what the source of necessitation, one cannot dissolve the problem of reconciling free will and the necessitation of the act willed simply by pointing out the difference between hypothetical and absolute necessity.
In other words, Leibniz appears to be taxing the fatalist and the determinist with a sophomoric error, namely, that of confusing (1) and (2) above. But no sophisticated fatalist or determinist need make that error. It is clear that my blogging now is a logically contingent state of affairs. But if determinism is true, then it is not nomologically possible that I be doing anything other than blogging now: past events under the aegis of the laws of nature necessitate my blogging now. How then can my blogging now be free? What Leibniz fails to see is that simply distinguishing the necessity of the consequence from the necessity of the consequent does nothing to answer the question.