essence can be known independently of experience--such at least is Leibniz's view. The apparent
greater plausibility of the cosmological as opposed to the ontological argument is therefore
deceptive.
The argument from the eternal truths is a little difficult to state precisely. Perhaps we shall do well
to state it first in rough outline, and only then proceed to the complete picture. Roughly, the
argument is this: Such a statement as "it is raining" is sometimes true and sometimes false, but
"two and two are four" is always true. All statements that have only to do with essence, not with
existence, are either always true or never true. Those that are always true are called "eternal
truths." The gist of the argument is that truths are part of the contents of minds, and that an eternal
truth must be part of the content of an eternal mind. There is already an argument not unlike this
in Plato, where he deduces immortality from the eternity of the ideas. But in Leibniz the argument
is more developed. He holds that the ultimate reason for contingent truths must be found in
necessary truths. The argument here is as in the cosmological argument: there must be a reason for
the whole contingent world, and this reason cannot itself be contingent, but must be sought among
eternal truths. But a reason for what exists must itself exist; therefore eternal truths must, in some
sense, exist, and they can only exist as thoughts in the mind of God. This argument is really only
another form of the cosmological argument. It is, however, open to the further objection that a
truth can hardly be said to "exist" in a mind which apprehends it.
The argument from the pre-established harmony, as Leibniz states it, is only valid for those who
accept his windowless monads which all mirror the universe. The argument is that, since all the
clocks keep time with each other without any causal interaction, there must have been a single
outside Cause that regulated all of them. The difficulty, of course, is the one that besets the whole
monadology: if the monads never interact, how does any one of them know that there are any
others? What seems like mirroring the universe may be merely a dream. In fact, if Leibniz is right,
it is merely a dream, but he has ascertained somehow that all the monads have similar dreams at
the same time. This, of course, is fantastic, and would never have seemed credible but for the
previous history of Cartesianism.
Leibniz's argument, however, can be freed from dependence on his peculiar metaphysic, and
transformed into what is called the argu-