Routledge History of Philosophy Volume IV

RENAISSANCE AND SEVENTEENTH-CENTURY RATIONALISM 363
thesis, given that relational predicates are excluded from complete concepts. But
here again the crucial point is taken to be that laws are built into complete
concepts. The idea is that the concept of an individual substance contains noncausal
laws of coexistence with other substances; from this it follows, as the
expression thesis requires, that the predicates of all other substances can be
deduced from the concept of a given substance. It is in this sense, then, that
‘every individual substance involves the whole universe in its perfect concept’. 37
This interpretation is attractive, for it frees Leibniz’s argument from its otherwise
obvious invalidity. But as its proponent acknowledges, it does so at a heavy
price; a complete concept turns out not to be a purely logical notion, for Leibniz
has packed some of his metaphysics into it. Thus the difficulty now is not that
Leibniz’s argument involves a non sequitur but that it is effectively questionbegging.
Before we conclude this section, it is worth clarifying thesis 4— that every
substance is the causal source of all its states. At a minimum Leibniz holds that
every state of a substance is caused by an earlier state of that substance. 38 But
Leibniz seems to be committed to more than this when he claims, as he often
does, that a substance gets all its states ‘out of its own depths’; 39 this phrase
suggests something crucial about the way in which the states of a substance are
caused by its earlier states. In fact, Leibniz’s view of intra-substantial causality
seems to draw on the ‘marks and traces’ version of the expression thesis.
Remember that, according to that thesis, a substance bears within itself the marks
of all its future states. Thus Leibniz holds that when an earlier state causes a later
state, this later state was in a sense latent or dormant in the substance all along;
when the state is caused, it emerges from quiescence and bursts into activity;
subsequently, it reverts to a condition of quiescence. The causing of a state thus
seems to be the activation of a ‘mark’ that was pre-existent in the substance
throughout its previous history.
THE DOCTRINE OF MONADS
The metaphysical doctrines 1–5 which, in the Discourse on Metaphysics, Leibniz
deduces from his logic all concern substances, and throughout his subsequent
career Leibniz continues to assert these doctrines; they are some of the great
constants of his philosophy. None the less, Leibniz’s metaphysics underwent a
major development between the Discourse (1686) and the Monadology (1714).
Although Leibniz never recants any of the five doctrines, he changes his mind
about what sort of items really fall under the concept of substance. In the
Discourse Leibniz holds, despite some hesitation, that all substances are either
organisms or souls; in his later philosophy he comes to hold that, strictly
speaking, there are no corporeal substances; rather, all substances are either souls
or at least soul-like. The later philosophy is thus a form of idealism inasmuch as
it maintains that the basic furniture of the universe is mental or spiritual in nature.
This is the famous doctrine of monads. 40 It may of course be questioned just how