This book is a defense of modal realism; the thesis that our world is but one of a plurality of worlds, and that the individuals that inhabit our world are only a few out of all the inhabitants of all the worlds. Lewis argues that the philosophical utility of modal realism is a good reason for believing that it is true.

According to one of Leibniz's theories of contingency a proposition is contingent if and only if it cannot be proved in a finite number of steps. It has been argued that this faces the Problem of Lucky Proof , namely that we could begin by analysing the concept ‘Peter’ by saying that ‘Peter is a denier of Christ and …’, thereby having proved the proposition ‘Peter denies Christ’ in a finite number of steps. It also faces a more general but (...) related problem that we dub the Problem of Guaranteed Proof . We argue that Leibniz has an answer to these problems since for him one has not proved that ‘Peter denies Christ’ unless one has also proved that ‘Peter’ is a consistent concept, an impossible task since it requires the full decomposition of the infinite concept ‘Peter’. We defend this view from objections found in the literature and maintain that for Leibniz all truths about created individual beings are contingent. (shrink)

Legendary since his own time as a universal genius, Gottfried Wilhelm Leibniz (1646-1716) contributed significantly to almost every branch of learning. One of the creators of modern mathematics, and probably the most sophisticated logician between the Middle Ages and Frege, as well as a pioneer of ecumenical theology, he also wrote extensively on such diverse subjects as history, geology, and physics. But the part of his work that is most studied today is probably his writings in metaphysics, which have been (...) the focus of particularly lively philosophical discussion in the last twenty years or so. The writings contain one of the great classic systems of modern philosophy, but the system must be pieced together from a vast and miscellaneous array of manuscripts, letters, articles, and books, in a way that makes especially strenuous demands on scholarship. This book presents an in-depth interpretation of three important parts of Leibniz's metaphysics, thoroughly grounded in the texts as well as in philosophical analysis and critique. The three areas discussed are the metaphysical part of Leibniz's philosophy of logic, his essentially theological treatment of the central issues of ontology, and his theory of substance (the famous theory of monads). (shrink)

Christia Mercer has exposed for the first time the underlying doctrines of Leibniz's philosophy. By analyzing Leibniz's early works she demonstrates that the metaphysics of pre-established harmony developed many years earlier than previously believed and for reasons that have not been understood. A much deeper understanding of some of Leibniz's key doctrines emerges. Christia Mercer's study will force scholars to reconsider their basic assumptions about early modern philosophy and science. This is a very significant contribution to the history of early (...) modern philosophy that will be of special importance to philosophers, historians of ideas, historians of science and those in religious studies. (shrink)

Leibniz war gewillt, die Idee der kontingenten Wahrheiten über nur mögliche individuelle Substanzen ernst zu nehmen -unabhängig davon, ob diese Substanzen existieren oder nicht. Einer der Wege, diese Idee zu erklären, ist die berühmte Lehre von der unendlichen Analyse. Eine wichtige und verwirrende Schwierigkeit für diese Lehre ist das von Robert M. Adams erörterte Problem des Beweises mit Glück. Auch wenn der vollständige individuelle Begriff einer möglichen Substanz S sich durch Analyse in unendlich viele einfache Begriffe zerlegen läßt, ist es (...) schwerlich erforderlich, daß der Beweis für das Enthaltensein eines Prädikats F im vollständigen Begriff von 5 unendlicher Analyse bedarf: Beweise gehen schrittweise vor; es ist offensichtlich möglich, daß einige Prädikate früher und schneller hergeleitet werden als andere. In diesem Aufsatz zeigen und entwickeln wir zwei leibnizische Wege, die das Problem des mit Glück kurzen Beweises beantworten. (shrink)