Remarks on Possibilia in Leibniz, 1672-1676: Quod non omnia possibilia ad intelligentiam perveniant?

n a recent article Fabrizio Mondadori studies in detail the scholastic background for Leibniz's view of possibilia . Mondadori concludes that, "Leibniz sharply distinguishes between the question of the possibility, and the question of the reality, of possibilia , and explicitly suggests that the reality - but not the possibility - of possibilia depends on the (actual) existence of God". 1 The expression 'the possibility of possibilia' might seem a bit cumbersome for making a simple point, namely that possibility for Leibniz depends on the principle of contradiction alone, so that possibilities are defined by freedom from contradiction (or by self-consistency) and depend on nothing else. In particular, and against Descartes' voluntarist view of the eternal truths, for Leibniz, possibility is independent of God's will. According to Leibniz, God finds all possibilities fully formed in his understanding. This point provides a central premise in Leibniz's early reasoning in the confessio philosophi that God is not to be regarded as the Author of sin. Sins are understood and then permitted existence by God as part of the most harmonious series of things, but they are found (among the ideas of all things) in God's understanding and are not willed or made by God. Thus, Leibniz's God cannot make something possible impossible or vice versa. This is governed by purely logical considerations stemming from the law of contradiction. Even if indeed cumbersome, this terminology (the possibility of possibilia ) brings out some of the historical context (in its traditional jargon) and highlights the contrast with the question of the reality of possibilia . 2 The thesis that the reality of possibila depends on God means that, according to Leibniz, possibilities are not free floating or self-sufficient like platonic forms; rather, they are conceived in God's understanding and are among the objects of his understanding. This gives rise to a difficult question: if God does not think certain possibilities, are they to be considered possible or not? In somewhat different words, does it make sense to claim that God does not conceive certain possibilities, i.e., self-consistent concepts? While possibilities are certainly independent from God's will, and depend on the principle of contradiction, they do not seem to be entirely independent from some thinking agent. As Massimo Mugnai notes, "there are no ideas without the intellectual activity of someone thinking (be it God or man or some other rational