Monadology
Leibniz's theory of monads was propounded most fully in his Monadology (1714). The monad is a simple substance, and everything in this world is composed of a number of monads. It has no parts, hence not divisible. But Leibniz's principle of sufficient reason prohibits the existence of no two individuals exactly alike. Then, how is it possible that a multitude of simple monads exist? Leibniz says that changes are continually going on in monads, and those changes come from an internal principle; no external causes can be allowed.
13. But we must also accept that in addition to this principle of change there is a detailed specification of the changes, which as it were determines a simple substance's species and variety.
Because of such changes, there arises a plurarity of states, or of relationships among the monads. But what does make it possible to bring about such changes?
14. The transitory state which incorporates and represents a multitude within a unity or within a simple substance is nothing but what we call perception ---
Perceptions are brought about by what Leibniz calls appetition (appetite). And perceptions can have degrees of distinctness, the more distinct, the more perfect. And the distinction between active and passive is related with this. A monad is said to be active in so far as it has perfection (with respect to something); passive in so far as it lacks perfection, i.e. in so far as its perception is confused. But, it must be noticed that, "mutual action and passivity" among monads are merely meant to be ideal, because what really bring about this distinction are God's interventions. Thus arises the interconnection among the monads. And now come crucial passages:
56. Now, this interconnection, or this adapting of all created things to each one, and of each one to all the others, means that each simple substance has relationships which express all the others, and that it is therefore a perpetual living mirror of the universe.
57. And just as the same town when seen from different sides will seem quite different, and is as it were multiplied perspectivelly, the same thing happens here: necause of the infinite multitude of simple substances it is as if there were as many different universes; but they are all perspectives on the same one, according to the different point of view of each monad.
As a possible interpretation in modern terms of Leibniz monadology, "perception" may be understood as the information contained in a given region (presumably a discrete area). The flow of information is necessarily subject to the law of thermodynamics: information decreases or entropy increases. But the totality of such flows of information determines the dynamics of the whole universe. And if we take the relationalist stance, as Leibniz certainly did, any local event (flow of information) is determined by the totality of the relationships, and it reflects, in an important sense, the rest of the world. The "holographic principle" in recent cosmology may be regarded as a partial realization of the Leibnizian idea (see my review of Greene and Smolin).
Last modified, June 30, 2005. (c) Soshichi Uchii