Leibnizs metaphysics is illustrated in his Monadology. He states that there are many substances, but only one is infinite (God) the others are finite. He calls simple substances monads. Only the infinite substance can act on any other. Hence any change in a monad must come from within - that is they are windowless - nothing "can enter or depart". Further no monad can act on another.

So to have them act in concert Leibniz outlines his dogma of the pre-established harmony, which is orchestrated by the only infinite substance.

But why must they act in concert? This is something not explained in the monadology - is it to be found in earlier Christian metaphysics?

  • I remember asking the same question of my modern philosophy professor. Unfortunately I was rather uninterested in the subject so the answer is a little blurred: I think it had to do with God not lying to us, hence making what we think we see in our own monads correspond to what's really going on.
    – commando
    Commented Jun 25, 2013 at 0:27
  • ok, our monad being our soul? Commented Jun 25, 2013 at 1:31
  • I think so. I'm a little rusty though.
    – commando
    Commented Jun 25, 2013 at 2:03
  • ok, I think I've got it. Commented Jun 25, 2013 at 2:19
  • Leibniz monad has 4 types: bare, perceptible, soul, rational. A living person in his monadology metaphysics is composed of infinite number of bare and perceptible monads just same as any hard cold matter or plants, but also endowed with a rational monad and a dominant soul monad. What's identify human from beasts is we have a rational monad. But since soul monad is dominant, this theory has very much similar conclusion such as those of David Hume who famously said "reason is, and ought only to be the slave of the passions", if we assume Hume's passion is very close to Leibniz's soul monad... Commented Mar 12, 2021 at 4:17

2 Answers 2


Yes, monads are souls. I would not be so fast in understanding Leibniz. Dont forget that he was very puzzled by continuity, so his statement that monads are finite does not mean that they are somehow less then god.. Finiteness+continuity=infinity. So, each monad has in principle infinite capabilities. Leibniz did his best to understand the world around him in terms of single soul. Basically the theory of monads is a theory of solipsism. Off course he did not wanted to be alone so infinity of god is needed - as always active source of power which can awake single monad and "change" it. But he understood very clearly the complete independence of single soul.

Going further in each monad we see that she is equivalent to god so -- other monads exist in it (infinite recursion) - and conclusion is that "other" monads act in concert because God(each monad) wants it!

Furthermore if god can act on every monad this basically means that they are connected and opposite interaction is possible so monads can act on other monads but only through god.

You can dig in it deeper - its very recursive.


The root cause of why all windowsless monads must act in concert is his famous pre-established harmony doctrine. Leibniz once used a famous 2 synced clocks thought experiment to try to explain this, but this doctrine was ultimately originated with his firm belief of Christian mono-thesism which contends perfect order of this created world. As a side-effect, this tacitly avoids the mind-body interaction dualism problem puzzling lots of academics till today.

Neithere his pre-established harmony nor monads act in concert was original and abstruse. His distinctive feature of monad is it's windowless while still capable of reflecting all outside monads' activities, thus it's not a type of solipsism, and windowlesness has many other implications...

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