The relation between leibniz's logical and his metaphysical views is the subject of much modern scholarship. Some commentators have argued that his metaphysics is based on his logic; others have taken the opposite position. However, Both sides pose the question in terms of 'priority'. On the contrary, I argue that it is likely that leibniz means the psr to play "both" a logical and a metaphysical role. The ambiguity of leibniz's psr indicates that he equates the metaphysical notion of causation (...) with the logical notion of deduction. The psr's ambiguity results less from any confusion on leibniz's part between the notions of cause and reason, Than from his desire to identify logic and metaphysics. That identity is achieved not by reducing one to the other, But by incorporating them on an equal basis into a single discipline. (shrink)

In discussion of Leibniz’s philosophical methodology Donald Rutherford defends the view that Leibniz regarded metaphysics as an a priori demonstrative science. In the course of this discussion Rutherford isolates and tries to deflect a significant challenge for his view, namely the observation that in many of his mature writings on metaphysics Leibniz appears to defend his views by means of a posteriori arguments. I present some prima facie difficulties with Rutherford’s position and then offer an alternative account of how Leibniz (...) thought he needed to establish metaphysical claims. My suggestion is that the challenge that Rutherford poses may be best answered by attending to the fact that Leibniz recognized a kind of metaphysical enquiry, ‘real metaphysics’, that is essentially a posteriori, in virtue of the fact that it is concerned not just with possible kinds of beings, but with the kinds of beings that God actually created. (shrink)

It is surprisingly difficult to determine what modal strength Leibniz wants to ascribe to his principle of the identity of indiscernibles (PII). I consider this question by examining (i) some direct textual evidence, (ii) Leibniz's main arguments for PII, (iii) Leibniz's presumable response to a prominent contemporary defense of the necessity of PII against Max Black style counterexamples, and (iv) Leibniz's views about the possibility of primitive haecceities. I conclude that Leibniz probably takes PII to be necessary.

Im Falle einer kontingenten Wahrheit 'S ist P' behauptet Leibniz sowohl, daß der Begriff von P im Begriff von S enthalten ist als auch, daß die Verbindung von S und P durch den göttlichen Willen besteht: Wie kann das angehen? Ich beantworte diese Frage, indem ich eine Deutung der Leibnizschen Doktrin von Wahrheit als Enthaltensein und seiner Auffassung vom vollständigen Begriff einer individuellen Substanz anbiete, nach der jene seinen Überlegungen darüber entspringen, inwiefern die 'Neue Wissenschaft' sich mit der traditionellen Unterscheidung (...) von Essenz und Akzidens nicht gut verträgt. Aus meiner Interpretation folgt dann, daß Leibniz' Theorie begrifflichen Enthaltenseins wie die verwandte Theorie der unendlichen Analyse auf einer Struktur beruhen, die in einigen, aber, wie sich zeigen läßt, nicht in allen möglichen physikalischen Ordnungen aufgefunden werden kann. Ich werde darlegen, daß diese Einsicht meine Interpretation nicht untergräbt. Zum Schluß deute ich an, inwiefern sich Leibniz' Überlegungen zur Kontingenz in Begriffen göttlicher Vermögen und in Begriffen unendlicher Komplexität ergänzen. (shrink)

In the Monadology Leibniz has us imagine a thinking machine the size of a mill in order to show that matter can’t think. The argument is often thought to rely on the unity of consciousness and the notion of simplicity. Leibniz himself did not see matters this way. For him the argument relies on the view that the qualities of a substance must be intimately connected to its nature by being modifications, limitations of its nature. Leibniz thinks perception is not (...) a modification of matter because it is active and matter is passive. At the same time, there are traces in Leibniz of a different argument that relies on the notion of internal action, which may involve the notion of simplicity. Critics have sometimes charged that the Mill Argument is an argument from ignorance, but Leibniz was aware of this problem and made clear that he did not make that mistake. (shrink)

In discussion of Leibniz’s philosophical methodology Donald Rutherford defends the view that Leibniz regarded metaphysics as an a priori demonstrative science. In the course of this discussion Rutherford isolates and tries to deflect a significant challenge for his view, namely the observation that in many of his mature writings on metaphysics Leibniz appears to defend his views by means of a posteriori arguments. I present some prima facie difficulties with Rutherford’s position and then offer an alternative account of how Leibniz (...) thought he needed to establish metaphysical claims. My suggestion is that the challenge that Rutherford poses may be best answered by attending to the fact that Leibniz recognized a kind of metaphysical enquiry, ‘real metaphysics’, that is essentially a posteriori, in virtue of the fact that it is concerned not just with possible kinds of beings, but with the kinds of beings that God actually created. (shrink)

Es hat sich als ausgesprochen schwierig erwiesen, für Leibniz' Auffassung, daß kontingente Wahrheiten unendlich komplex sind, eine Interpretation zu finden, die diese Auffassung kohärent erscheinen läßt. Dies liegt daran, daß seine Kommentatoren dazu neigen, sich für die unendliche Analyse einer kontingenten Wahrheit am Vorbild eines nicht endenden logischen Beweises zu orientieren. Ich versuche hingegen zu zeigen, daß unendliche Analysen als unendliche Reihe immer komplexerer und detaillierterer physischer Argumente aufgefaßt werden sollten. Ferner versuche ich zu zeigen, daß die Theorie der unendlichen (...) Analyse speziell für die Wahrung dessen entworfen wurde, was man ,innerweltliche' Kontingenz nennen könnte, d.h. einer Kontingenz, die aus internen Merkmalen einer gegebenen moglichen Welt hervorgeht, im Gegensatz zu einer Kontingenz, die aus Überlegungen dariiber entsteht, welche anderen Welten Gott geschaffen haben konnte. Um innerweltliche Köntingenz geht es, wenn Leibniz scheinbare Gefahren für die Freiheit betrachtet, die aus seiner Erklärung von Wahrheit als einem begrifflichen Enthaltensein entstehen. (shrink)