LEIBNIZ ON HUMAN FREEDOM

A. A bad argument against human freedom starts from God's omniscience.

    1. The argument  [Assume that it's true that Adam sins.]

      (P01) God is omniscient.

      (L02) God knows that Adam sins. [(P01)]

      (P03) If God knows that Adam sins, then Adam sins.

      (L04) It's necessary that Adam sins. [(L02, P03)]

      (C)    Adam's sinning is not free. [(L04)]

    2. Criticism

        a. (L04) doesn't follow from (L02) and (P03).

        b. All that follows is that Adam sins. (Also, if (L02) and (P03) are certain, it follows that it's certain that Adam sins.)

        c. The reason someone might think that (L04) follows is that (P03) is a necessary truth. So we have an inference of 
          the form 'P & Nec if P then Q, so Nec Q'.

        d. But this inference is fallacious: it is indeed a common modal fallacy so to argue.

        e. It might be claimed that (L02) is a necessary truth as well, since (P01) is such a truth.

              i. But no, for what (P01) means is that God knows everything that's true, i.e. that if P is true then God knows that P.

             ii. This means that (L02) is a necessary truth only if it's necessary that Adam sins.

            iii. But to assume this is to beg the question at issue, i.e. to take for granted the very thing the argument is supposed 
               to establish, viz. that it's necessary that Adam sins.


B. A better argument against freedom, based on Leibniz's own metaphysics, was proposed by Arnauld.

    1. The argument. [Arnauld is responding to Leibniz's Discourse on Metaphysics, Sect. 13.]

      (P01) "The individual concept of every person involves once for all everything which will ever happen to him." (Leibniz's 
              claim in Discourse 13)

      (P02) "If this is so, [and if] God ... create[d] [Adam], all that [then] happened to [Adam] ... occurred ... by a necessity more 
              than fatal."

      (P03) God did create Adam.

      (P04) Adam's sin occurred soon after his creation.

      (C)     Adam's sin occurred "by a necessity more than fatal". [(P01,P02,P03,P04)]

    2. Leibniz made several responses to this argument.

        a. He claimed that the proposition that Adam sinned is true and certain, but that it is true contingently and not necessarily.

        b. He claimed that Adam sinned because he willed to do so, hence that his action accorded with his will; he then defined 
          'a free action' as one done in accordance with the agent's will, so that Adam's sin is a free action after all.

        c. He claimed that Adam's sin was 'spontaneous action' on his part, and defined a free action as a spontaneous action, 
          where a spontaneous action is one done by the agent himself and/or under his own control, as opposed to being forced 
          to act by some external factor and/or something not under one's own control.

    3. These responses themselves have been or could be questioned, by Arnauld and/or others.

    4. The upshot is that it is not clear that genuine human freedom is compatible with Leibniz's metaphysics. The issue is still 
       being discussed, and no consensus has been reached.