## 1. Competing Theories of Causation



Leibniz assumes that all events have causes--they do not just
happen--and typically considers only three theories of causation
worthy of philosophical consideration: physical influx, occasionalism,
and parallelism. Interestingly, Leibniz excludes from this list
Spinoza's aspect theory of causation. For it is apparent that
Leibniz thinks that any view that entails the existence of one and
only one genuine substance can not even begin to offer a proper theory
of causation. Let's summarize in turn each of the theories that
Leibniz does take seriously.



According to the theory of physical influx, there is an inflow between
cause and effect; in other words, there is intersubstantial causation
among finite (i.e., non-divine) substances. So, for instance, when
Jimi Hendrix appears to strum his guitar, he really is the cause of
the vibration of the strings. In this case, motion is a mode or state
of the body of Hendrix and is transferred or communicated to the body
of his guitar. Interestingly, the term 'physical'
notwithstanding, the theory of physical influx is not limited to
material finite substances. For physical influx sometimes is invoked
to explain the causal interaction among immaterial finite substances
(e.g., minds) and material finite substances (e.g., bodies).
Accordingly, it is more accurate to take the term
'physical' to mean natural rather than material. Francisco
Suarez, Thomas Hobbes, Pierre Gassendi, and Robert Boyle, among
others, subscribed to some variety of physical influx.



Occasionalism denies causation not only among finite substances, and
so rules out any inflow between cause and effect, but also within
finite substances. In other words, regarding finite substances, there
is neither intersubstantial nor intrasubstantial causation. Taken
individually or jointly, finite substances have no genuine causal
efficacy. When the strings of Hendrix's guitar vibrate, Hendrix
is not the real cause of the vibration. Nor are his fingers, wrist,
and arm real causes. Is the vibration then uncaused for the
occasionalist? No, for there is God. God, thought by many of
Leibniz's contemporaries to be the only infinite substance, is
considered to be the only real cause. God causes the strings on
Hendrix's guitar to vibrate on the occasion of Hendrix's
volition--itself caused by God--to strum the strings on his
guitar. Al-Ghazali, Nicolas Malebranche, and Louis La Forge, among
others, were occasionalists.



Like occasionalism, the theory of parallelism holds that there is no
intersubstantial causation among finite substances. And like
occasionalism, when the strings of Hendrix's guitar vibrate,
Hendrix is not the real cause of the vibration. Nor, again, are his
fingers, wrist, or arm real causes. Nevertheless, it is not God who is
the total real cause of this vibration. According to parallelism,
finite substances can be real causes. Rather the strings themselves
are causing themselves to vibrate. Due to the special harmony between
mind and body and not because of any direct causal relation, when
Hendrix is in a state of willing his fingers to strum the strings on
his guitar, the strings are in a physical state that would result in
their vibration.



Leibniz was and is the most famous proponent of parallelism. His
version is properly called "pre-established harmony" and
is usually interpreted to encompass five main tenets:


1. no change in the states of a created substance is due to another
created substance (i.e., there is no intersubstantial causation);
2. all (non-initial, natural) change in the states of a created
substance is due (at least in part) to that substance itself (i.e.,
there is intrasubstantial causation);
3. each created substance has a "blueprint" (i.e., a
complete concept or law of the series) that "lists" or
includes all of its states,
4. each "blueprint" conforms with the blueprints of all
other created substances (i.e., each of a created substance's
natural states cohere with all the natural states of every other
created substance); and,
5. this conformity between the states of substances is set up by a
universal cause, namely, God.



For expression of these four tenets, see, for example, Leibniz's
letters to Arnauld, Nov. 28/Dec. 8 1686 and Apr. 30 1687, and
*Monadology* SS81. Consider also this 1704 articulation of
the pre-established harmony:



> 
> Each of these souls expresses in its own manner what occurs outside
> itself, and it cannot do so through any influence of other particular
> beings (or, to put it a better way, it has to draw up [*devant*] this
> expression from the depths of its own nature); and so necessarily each
> soul must have received this nature--this inner source of the
> expression of what lies without--from a universal cause
> [*cause universelle*], upon which all of these beings depend
> and which brings it about that each of them perfectly agrees with and
> corresponds to the others. (*New Essays* A vi, 6, 440)
> 



As to be expected, there is some controversy regarding the
interpretation of these tenets; for instance, tenet 2 is sometimes
extended to also include non-initial states (see Whipple, 206). There
is another important aspect of the pre-established harmony. A
substance's expressions arising "from the depths of its
own nature" are also called perceptions by Leibniz. Perception
is "[t]he passing state which involves and represents a
multitude in a unity" (*Monadology* SS14 GP vi,
608/AG 214). The pre-established harmony consists in the isomorphic
mapping of perceptions and bodily motions. Whenever a substance has a
perception x there will be a corresponding bodily state y expressing
that perception x. So when I perceive myself as putting a log in the
fire "[my] animal spirits and [my] blood [take] on, at exactly
the right moment, the motions required to correspond to the passions
and the perceptions of [my] soul" (*New System* GP iv,
484/L 458).



Note, however, that the five main tenets of Leibniz's
pre-established harmony leave room for God's supernatural causal
activity even in the actions of finite substances. In other words,
pre-established harmony, in Leibniz's hands at least, is a form
of concurrentism. More of this will be addressed in the section on
divine causation, but for now it is enough to say that God's
causal role in the actions of finite substances at the very minimum is
to pre-establish the concomitance or conjunction between
"causes" and "effects," without which
God's aim of producing universal and maximum harmony
(*Monadology* SSSS85ff) would be frustrated.



Why is Leibniz drawn to the rather bizarre-sounding pre-established
harmony? In other words, why does he reject the more terrene physical
influx and the more celestial occasionalism?


## 2. Why does Leibniz reject Physical Influx?



Leibniz wants to rule out any kind of causation in which one substance
passes something on to the other substance: "The way of
influence belongs to that of the common philosophy. However, since it
is impossible to conceive of material particles or of species or
immaterial qualities that can pass from one of these substances into
the other, the view must be rejected" (GP iv, 498f). Early in
his career, Leibniz dismisses the physical influx theory of the
Scholastic Francisco Suarez as a "barbaric expression ...
metaphorical and more obscure than what it defines" (Preface to
an Edition of Nizolius GP iv, 150). (Whether Suarez actually held the
view Leibniz ascribes to him is another matter entirely.) Moreover,
the pre-established harmony can achieve the same effect without the
metaphysical baggage of "property passing": "So
there will be a perfect accord between all these substances which
produces the same effect that would be noticed if they all
communicated with each other by a transmission of species or of
qualities, as the common run of philosophers imagine" (*New
System* GP iv, 484/L 457f).



It is fairly clear here that Leibniz takes 'influx' to
refer to the transference of accidents--today we call them tropes
or property-instances--as when a guitarist's fingers give
an instance of motion to a struck guitar string. Leibniz holds that it
cannot be comprehended how one finite substance could act on another
finite substance. For such intersubstantial causation entails the
transference or migration of an accident from one substance to
another, where a trope passes from one thing to another, which then
instantiates it. Such transference is inexplicable; an accident
passing (i.e., trope transferring) from one subject to another is
impossible (*New Essays* A vi, 6, 224). Leibniz writes in the
*Discourse on Metaphysics*:



> 
> ... nothing ever enters into our mind naturally from the outside;
> and we have a bad habit of thinking of our soul as if it received
> certain species as messengers and as if it has doors and windows. We
> have all these forms in our mind; we even have forms from all time,
> for the mind always expresses all its future thoughts and already
> thinks confusedly about everything it will ever think about
> distinctly. (*Discourse on Metaphysics* SS26 GP iv, 451/AG
> 58)
> 



And he writes almost three decades later: "Monads have no
windows, through which anything could come in or go out. And accidents
cannot detach themselves and stroll about outside of substances, as
the Scholastics' sensible species used to; so neither substance
nor accident can come into a monad from outside"
(*Monadology* SS7 GP vi, 608/WF 268).



Leibniz also argues in this way: If the mind (one finite substance)
were to act on the body (another finite substance) thereby causing
bodily motion, there would be an increase in motion in that region of
the world after the mind's action on the body not compensated
for by a decrease in motion in another region. This is an obvious
violation of the law of the conservation of motion. Therefore, there
is no physical influx. The *Monadology* includes the following
passage:



> 
> Descartes recognized that souls cannot impart a force to bodies
> because there is always the same quantity of force in matter [i.e.,
> the material world]. However, he thought that the soul could change
> the direction of [force in] bodies. But that is because the law of
> nature, which also affirms the conservation of the same total
> direction in matter, was not known at that time. If he had known it,
> he would have hit upon my system of pre-established harmony.
> (*Monadology* SS80 GP vi, 620f/AG 223)
> 



Part of what troubles Leibniz about the doctrine of physical influx is
that in acting, the cause is drained. According to Leibniz, real
causation entails that the cause not lose any of its efficacy after
exercising its causal power. Leibniz depicts the production of our
thoughts, for instance, as involving emanative causation: "it is
very evident that created substances depend upon God, who preserves
them and who even produces them continually by a kind of emanation,
just as we produce our thoughts" (*Discourse on
Metaphysics* SS14 GP iv, 439/AG 46). Other commentators have
put it this way: "[S]ubstances are to be understood as enjoying
a lawful primitive force of action whereby accidents emanate from the
substance, from within" (Cover & O'Leary-Hawthorne,
181).



It is hard to tell why Leibniz is troubled by any theory that involves
the potential loss of causal efficacy in substances. Part of it might
have to do with his belief that even finite, created substances are
naturally indestructible (i.e., immortal) (*Principles of Nature
and Grace* SS2 GP vi, 598/P 195). For then created, finite
substances, continually acting according to the physical influx model,
might eventually lose their causal efficacy and would no longer be
able to act. And for Leibniz, "substances cannot be conceived in
their bare essence, devoid of activity; that activity is of the
essence of substance in general" (*New Essays* A vi, 6,
65). So, physical influx would entail the natural mortality of
substance, a view that Leibniz wholly rejects.



Consider another expression of Leibniz's anti-influx
position:



> 
> No created substance exerts a metaphysical action or influence on
> another, for to say nothing of the fact that it cannot be explained
> how anything can pass over from one thing into the substance of
> another, it has already been shown that all the futures of each thing
> follow from its own concept. What we call causes are in metaphysical
> rigor only concomitant requisites. (*Primary Truths* C 521/L
> 269/AG 33)
> 



Now, the idea here of causes as concomitant requisites and of God
"preserving" substances continually by a kind of emanation
may suggest occasionalism, but it is clear that Leibniz, after
initially showing some sympathy toward occasionalism, eventually
rejects it.


## 3. Why does Leibniz reject Occasionalism?



Occasionalism puts forward a view where God must act for any substance
that does not have the causal power itself to act. But since no other
substance besides God has the causal power to act for itself, or even
in conjunction with other finite substances, God must continually
intervene in the course of the world. Leibniz sees this as a serious
problem for the occasionalist account of causation.



Since occasionalism entails that God must continually intervene in the
course of nature, Leibniz takes this to mean that he must perform
continuous miracles--an occupation not entirely worthy of
God's name. He explains:



> 
> Let us see, however, whether the system of occasional causes really
> doesn't involve a perpetual miracle. [Pierre Bayle] said that it
> does not, because the system holds that God acts only according to
> general laws. I agree that he does, but in my view that isn't
> enough to remove miracles. Even if God produced them all the time,
> they would still be miracles, if the word in understood not in the
> popular sense, as a rare and marvelous thing, but philosophically, as
> something which exceeds the power of created things. It isn't
> sufficient to say that God has made a general law, for in addition to
> the decree there has also to be a natural way of carrying it out. It
> is necessary, that is, that what happens should be explicable in terms
> of the God-given nature of things. (*Explanation of Bayle's
> Difficulties* SS7 GP iv, 520/WF 205)
> 



Note Leibniz's definition of a miracle as simply an event that
results from God and not from finite substances. However, Leibniz
adds, a world in which God is required to perform continuous miracles
is a world less perfect, and thereby less praiseworthy, than a world
that "unfolds" naturally without the direct intervention
of God (*Theodicy* SS16). The idea is that the doctrine of
occasionalism must hold that God did not initially get creation right
(even if the occasionalist themselves is not willing to make such an
assertion) and so must continually step in and repair things to get
them to go the way God intends. (This is, of course, not to say that
for Leibniz there are no miracles whatsoever. He does speak of events
that "surpass all the force of creatures"
(*Theodicy* SS249 H 280), including the Creation and the
Incarnation.) Some have called Hendrix's guitar playing
"miraculous," but this is not because his playing was due only to God.
Hendrix was a real cause. 



For Leibniz, a world of genuinely active substances is more perfect
than a world of purely passive or causally inert substances, whose
activity is not properly ascribed to them but to God. Ascribing such
activity to God alone, Leibniz believes, leads inexorably to
Spinozism, where God is the only real substance and where any other
thing is just a mode of God or else must invoke a deus ex machina,
which for Leibniz is an ad hoc solution (*Primary Truths* C
521/P 90; GP iv, 515/WF 221). In order to avoid what he thinks is
unadulterated Spinozism, Leibniz is keen to emphasize that we must be
able to distinguish the actions of God from the actions of created
substances. (The success of this endeavor of Leibniz's is
debatable, as discussed in the section on divine causation.)



Interestingly, Leibniz also offers a methodological reason for
rejecting any view that unnecessarily invokes miracles to explain
phenomena: "In philosophy we must try to show the way in which things
are carried out by the divine wisdom by explaining them in accordance
with the notion of the subject we are dealing with" (*New
System* SS13 WF 150). 


## 4. Intersubstantial Causation



Since Leibniz seems to think that intersubstantial causation requires
physical influx and physical influx is unacceptable, he concludes,
logically enough, that we must reject intersubstantial causation. But
Nicholas Jolley notes that Leibniz does not always argue this way. For
while consistently rejecting the existence of influx, sometimes
Leibniz will not at the same time reject outright the existence of
intersubstantial causation. "Leibniz sometimes suggests that our
ordinary statements about causal interaction can be understood in such
a way that they come out true" (Jolley 1998, 595). Nevertheless,
Jolley continues, "When Leibniz simply denies the existence of
causal interaction between created substances, he tends to accept the
influx analysis; he does not look around for a better analysis that
would preserve the truth of our ordinary causal statements"
(Jolley 1998, 595). So, on the whole, Leibniz does not take seriously other
alternative accounts of intersubstantial causation.



Perhaps because he thinks he already has an account that will work for
him--the pre-established harmony--Leibniz does not believe
that a plausible theory of causation need be intersubstantial in kind.
In other words, Leibniz does not face a problem so many of his
contemporaries face: his metaphysics--unlike their
own--includes the necessary (and sufficient?) elements to sustain
a properly and purely intrasubstantial theory of causation; a
Leibnizian created substance is self-sufficient (possessing an inner
principle of change that explains all of its property-instances),
permanently causally efficacious (acting does not diminish its power),
and equipped with a complete concept that conforms to the complete
concepts of all other created substances (perceiving or representing
one and the same universe). Thus, it makes sense that Leibniz would
not feel compelled to defend intersubstantial causation. Like
reference to miracles, it would be an unnecessary move, and therefore
methodologically invalid. 



This point can be alternatively expressed. A difficult problem in
giving an account of intrasubstantial causation concerns the
explanation of the difference between causation among systems and
causation within a system. For instance, do the works of a watch
constitute an isolated system? For even Rolexes, constructed for
deep-sea divers, are affected at extreme temperatures and depths. So
there is a problem giving an account of causation within a Rolex. A
similar problem arises for a seventeenth century philosopher who holds
a mechanistic and materialist notion of substance. But Leibniz has no
problem with explaining the difference between systems that are
causally isolated and systems that cannot be made absolute; his
monadic ontology is readily equipped to handle causally isolated units
or unities. For his substances are "windowless," not at
all causally compromised by external substances.



> 
> There is ... no way in which it could make sense for a monad to
> be altered or changed internally by any other created thing. Because
> there is nothing to rearrange within a monad, and there is no
> conceivable internal motion in which it could be excited, directed,
> increased, or diminished, in the way that it can in a composite, where
> there is change among the parts. Monads have no windows, through which
> anything could come in or go out. And accidents cannot detach
> themselves and stroll about outside of substances, as the
> Scholastics' sensible species used to; so neither substance nor
> accident can come into a monad from outside. (*Monadology*
> SS7 GP vi, 608/WF 268)
> 



In other words, Leibniz writes, "substances can never prevent
one another from performing those works in this universe as far as is
possible" (Letter to Arnauld April 30, 1687 SS6 WF 125).



In what follows, I will focus on Leibniz's positive account of
causation. The only real causation present in Leibniz's
metaphysics is that within each finite substance and that of God who
pre-establishes the harmony among minds and bodies (and minds and
minds, and bodies and bodies). So the rest of this entry will address
intrasubstantial and divine causation.


## 5. Intrasubstantial Causation



Whatever can be predicated of a Leibnizian substance is either an
attribute (a permanent and common characteristic (GP ii, 227, 257ff)),
sometimes called "property" (GP ii, 258/L 533), or an
accident (a transitory and individual characteristic (GP ii, 458/L
605; GP iv, 363)), sometimes called "modification" (G ii,
258/L 533; GP ii, 503f). In contemporary lingo, we would call an
attribute a "property" and accident a
"property-instance" or "trope." Action is an
attribute of substance, for Leibniz defines substance as "a
being capable of action" (GP vi, 598). A perception is an
accident of a substance, for the action of a substance consists
precisely in the fact that they are always changing their perceptions.
Now, an attribute must not be considered a substance, since it would
be a mistake to equate action with what is acting, or extension with
what is extended (*New Essays* A vi, 6, 210f). Neither is an
attribute to be considered an accident, for "an attribute may be
predicated of several substances at the same or at different times
while an accident can never inhere in more than one substance at the
same or at different times" (Clatterbaugh, 1978, 3).



So, for Leibniz, the essence of a created substance is activity, in
the sense of being continually in process of change of its perceptions
(Letter to De Volder, January 21, 1704, GP ii, 263/L 534). The
accidents (tropes or property-instances) of a substance are its
perceptions. The change in a created substance must be caused
(*Primary Truths* C 519/L 268), yet there can be no transeunt
(i.e., intersubstantial) causation (*Discourse on Metaphysics*
SS14, GP iv, 439/L 312/WF 66f). For causal interaction between
created substances (i.e., monads) is in principle inexplicable
(*New System* GP iv, 483/L 457) as seen earlier. Therefore, the
cause of change of perceptions in a created substance is either to be
located in an uncreated substance, namely God, or in the substance
itself. But, as we have already seen, Leibniz rejects the view that
God alone is the real causal power driving change in substances; as
previously shown, he is no occasionalist (*Notes on a Reply of
Foucher*, GP i, 373f/L 155). So, putting God aside for the moment,
perceptual change is caused by the substance itself. But surely we
want to know what it is about the substance or in the substance that
drives perceptual change.



What exactly causes the change of perceptions of a substance? Leibniz
holds that both the "primitive active power" of a
substance and its perceptions or perceptual states play crucial causal
roles in the changes of a substance. (As we shall see, furthermore,
God is no minor player in this effort as well.) The primitive active
power of a substance, Leibniz tells us, is "a nature or an
internal force that can produce in it, in an orderly way ... all
the appearances or expressions it will have, without the help of any
created being" (*New System* GP iv, 486/AG 144).
Moreover, "the present state of each substance is a natural
result [*consequence*] of its preceding state"
(*Clarification of Difficulties concerning Monsieur Bayle* GP
iv, 521).



To be clear, however, primitive powers and perceptions do not play the
same causal roles, according to Leibniz. Whereas the primitive power
of a substance (some commentators maintain that primitive powers and
substances are one and the same) is the efficient cause--a
post-Humean might say the real cause--of the change of its
perceptual states, these states themselves do not function as
efficient causes. How perceptual states do function causally is
controversial, and we will address this issue later. Whatever the
final details of Leibniz's account happen to be regarding
primitive power and perception, one thing is clear: Leibniz's
account runs seriously counter to David Hume's regarding
causation. In 1748, Hume stated that his definition of cause entails
that "all causes are of the same kind" (*An Enquiry
Concerning Human Understanding*, 156), whereas Leibniz
incorporates efficient, final, and formal causes in his theory of
causation. Before discussing these different kinds of causes, however,
let us consider a particularly vexed issue in Leibniz's account
of causation: divine causation.


## 6. Divine Causation



> 
> It is difficult to distinguish the actions of God from those of
> creatures, for some believe that God does everything, while others
> imagine that he merely conserves the force he has given to creatures.
> (*Discourse on Metaphysics* G iv, 432/AG 40)
> 



Not all systems of pre-established harmony are the same.
Leibniz's own version represents a form of concurrentism, since
he rejects the view that the change in perceptual states of a created
substance is due solely to that created substance itself. As he
writes, "Each and every substance is the true and real cause of
its own immanent actions and has the power to act ... sustained
by divine concurrence" (A vi, 4 Strickland 2006). According to
Leibniz, both God and created substances are causally responsible for
changes in the states of created substances. But God is no minor
player in this effort; God is immediately and directly causally
present in every aspect of the universe, even in those effects
normally attributed to created substances. Consider these two
texts:



> 
> 
> [God] operates immediately on all created things, continually
> producing them ... (*New Essays* A vi, 6, 222)
> 
> 
> 
> God continually produces all that is real in creatures. But I hold
> that in doing it he also continually produces or conserves in us that
> energy or activity which according to me constitutes the nature of
> substance and the source of its modifications. (*New System* GP
> iv 588f/Adams, 98)
> 
> 
> 



Leibniz argues for this view in the Theodicy: "the action of God
in conserving should have some reference to that which is conserved,
according to what it is and to the state wherein it is; thus his
action cannot be general or indeterminate" (*Theodicy*
SS27). So even though Leibniz rejects occasionalism, Leibniz does
agree with the occasionalist Malebranche that God must be given his
causal due. It is certainly not a mere afterthought. In fact, both
agree that "conservation is continual creation." Consider
another two passages from Leibniz:



> 
> 
> [T]he duration of things (the multiplicity of momentary states) is the
> total of an infinity of divine fulgurations, of which each one at each
> instant is a creation or reproduction of everything; which strictly
> speaking leaves no continuous passage from one state to the next. This
> provides a perfect proof of that famous truth of Christian theologians
> and philosophers, that the conservation of things is a continual
> creation; and it gives a very special way of verifying the dependence
> of every changeable thing on the unchangeable divinity ....
> (Letter to Sophie Charlotte GP vii 564f)
> 
> 
> 
> And when it is said that the creature depends upon God insofar as it
> exists and insofar as it acts, and even that conservation is a
> continual creation, this is true in that God gives always [*donne
> toujours*] to the creature and produces continually all that in it
> is positive, good and perfect, every perfect gift coming from the
> Father of lights. (*Theodicy* SS31)
> 
> 
> 



Commitment to continual creation is thus an important constraint on
Leibniz's theory of causation. Ultimately, Leibniz adopts a form
of concurrentism in which the natural change in the perceptual states
of a created substance is due to the direct involvement of
*both* the created substance and God. In other words, created
substances possess genuine causal powers even while God's own
causal power is flexed everywhere in creation, including that of
created substances and their states.



Since God's causal activity complements created substances,
including our own, Leibniz does not count such activity as miraculous.
Miracles are *interventions* in the natural course of events.
Properly speaking then, this activity is not intervention on
God's part, but divine cooperation or concurrence. Leibniz
writes: "In concurring with our actions, God ordinarily does no
more than follow the laws he has established, that is, he continually
conserves and produces our being in such a way that thoughts come to
us spontaneously or freely in the order that the notion pertaining to
our individual substance contains them, a notion in which they could
be foreseen from all eternity" (*Discourse on
Metaphysics* SS30 AG 63).



Should we take take Leibniz's word for it? Some commentators are
not convinced that Leibniz consistently advocates concurrentism, for
if the doctrine of continual creation was taken seriously (that is,
that God continuously produces all things), then how can anything but
occasionalism be the natural upshot? David Scott puts it this way:
"After all, it is a fundamental Leibnizian tenet that the
'degree of perfection' of a thing is the extent to which
that thing acts. [*Discourse on Metaphysics* SS15] Thus, if
a thing's perfection or action is 'due to God' (as
opposed to itself) then we have a de facto occasionalism in which God
does all the work. The question here is what sense can be made of the
idea that God's conservation is a 'support' for the
'natural permanence of a thing which comes into
existence'" (Scott SS4). Scott continues to claim that
"the notion of God supporting the natural permanence of things
is a contradiction in Leibnizian terms, resolvable only if a greater,
occasionalist-like dependence of nature upon God is admitted."
The problem, however, is that Leibniz certainly does reject
occasionalism and specifically tries to show (unsuccessfully,
according to Scott) that continual creation is consistent with the
genuine causal activity of created substances. Perhaps it is
inescapably philosophically untenable, but Leibniz's view is
that "[God's action] cannot be general or indeterminate.
... Conservation by God consists in the perpetual immediate
influence which the dependence of creatures demands"
(*Theodicy* SS27).



It may be tempting to say that for Leibniz we know *that* God
does act on created substances continually, but we cannot understand
*how* he does this. Consider what Leibniz writes in the *New
Essays*: "[A]ll monads were created by God and depend on
him; yet we cannot understand in detail how this was done; and
fundamentally the preservation of monads is nothing but a continual
creation, as the Scholastics knew very well" (*New
Essays* A vi, 6, 443). Perhaps Leibniz simply adopts the Cartesian
stance--that God is a *sui generis* cause, the likes of
which we would be rash to think we can learn anything meaningful.



Unlike Descartes, however, Leibniz does try to explain how God acts on
creatures: "created substances depend on God, who conserves them
and even produces them continually by a kind of emanation as we
produce our thoughts" (*Discourse on Metaphysics*
SS14 GP iv 439/PM 26). This suggests Leibniz's preferred way
of reconciling God's creation and concurrence with creaturely
activity. Continual creation is to be understood in terms of
God's emanative activity. Emanation is how God sustains the
activity of substances.



Leibniz's appeal to emanation needs some explanation and
defense, however. Jonathan Bennett, for one, finds this idea
"astonishing":



> 
> When we "produce our thoughts," we cause some alteration
> in ourselves; that is, our thoughts "emanate from our
> substance" only because the substance has the thoughts, just as
> faces have blushes, bowls have shapes, and so on. Leibniz's
> comparison implies that God's conserving us is his causing
> himself to be in some state, which then implies that we are not
> separate substances, but rather states or modes of God. Leibniz would
> reject that, calling it "Spinozism." I do not understand
> his offering a comparison which so obviously implies it. (Bennett,
> 245)
> 



It us debatable whether Bennett fully grasps Leibniz's analogy.
The point of Leibniz's analogy between substantial thought or
perception and God's conservation is to reveal two important
aspects of emanation: (1) that God's causal influence on us is
continual (just as substances always perceive); and (2) that this
influence does not diminish God's causal power (just as thinking
does not seem to diminish our ability to think) (Mercer, 189).



Since a substance is more perfect than its mental states, the power of
a substance is in no way diminished when it perceives or thinks. The
active principle in a substance offers thoughts to
itself--thoughts produced by emanation (Mercer, 325, 366f). A
third aspect of emanation is equally important: Neither the emanator
(God) nor the emanatee (created substance) is diminished causally. We
can attribute to Leibniz the following view: God's role in
intrasubstantial causation, besides that which is implied by
miraculous intervention, is an emanatory one (*Discourse on
Metaphysics* SS28; *New Essays* A, 6, 210f). An
emanative mode of causal activity is one in which the cause includes,
in some "eminent" or higher form, what it gives to its
effect, without losing the ability to produce the same kind of effect
in the future. But a substance, undergoing this kind of intervention
or causal process, need not lose its natural causal efficacy. So I
think that Bennett misses the main implication of the *Discourse on
Metaphysics* SS14 passage; the implication is *not*
that we are modes of God, but that our causal agency is analogous to
God's. Causally speaking at least, we are made in the image of
God. (This feature of emanation also reveals one shortcoming of
Jeffrey McDonough's otherwise excellent analogy of divine
continual creation. McDonough points out that "my freezer can be
thought of as creating and conserving particular ice cubes through a
single continuous action that begins when a tray of water is put in
the ice box, and ends when the cubes are removed" (McDonough,
2007, 50). This analogy nicely captures the concurrence of continual
creation but it fails to capture the non-entropic nature of such
creation, for freezers are certainly not 100% efficient.)



There is another problematic aspect of Bennett's analysis of
Leibniz's thought analogy. He seems to suggest that something
that has causal power must necessarily have productive causal power.
Bennett asks rhetorically: If we are to God as our thoughts are to
ourselves, then how can we produce anything? But it would be a mistake
to think that Leibniz would concur with such an inference. In fact,
Leibniz probably would not, since final causes clearly figure into his
account of the causal power of created substances: "perceptions
in the monad arise from one another by the laws of appetites, or by
the laws of the final causes of good and evil, which consist in
notable perceptions, ordered or disordered" (*Principles of
Nature and Grace* SS3 GP vi 598/AG 207). These appear to be
genuine causes in Leibniz's metaphysics, giving potency to
created substances, and helping serve to "distinguish the
actions of God from those of creatures" (*Discourse on
Metaphysics* SS8); however, echoing Aristotle, final causes
are not productive causes. There is a general moral to be gleaned here
as well. Unless Leibniz indicates otherwise, it is a mistake to equate
causal power and activity with productive or efficient causality. (Not
surprisingly, there is a further complication here. For, as we will
see in the next section, at least one commentator thinks that for
Leibniz some final causes are actually efficient.)



Leibniz wants to reconcile continual creation with creaturely causal
power and activity in order to defend concurrentism, and now we can
see that a promising answer (at least as a way of understanding
Leibniz) is to understand continual creation as a kind of emanation.
Emanation seems compatible with God's "continual
creation" (that is, immediate and direct causal influence on and
continual production of all things) and the power, activity and so
(relative) autonomy of created substances. In other words, continual
creation need not be understood as an occasionalist doctrine. But in
what sense precisely are created substances genuine causes? What
grounds the causal power, activity, and (relative) autonomy of
creatures? We need to gain a better sense of Leibniz's account
of intrasubstantial or immanent causality.


## 7. Efficient (Productive) Causation



To understand Leibniz's theory of intrasubstantial causality
better (and also to acquaint ourselves with some interpretive
difficulties), let us first focus on considerations having to do with
efficient causation. Then we will discuss final and formal
causation.



A point of terminological clarification is needed. According to
Leibniz, the terms 'efficiently cause' and
'produce' are synonymous: "It must be admitted that
in saying that 'efficient cause' is what produces and
'effect' is what is produced, you are merely dealing in
synonyms" (*New Essays* A vi, 6, 228). Elsewhere, Leibniz
defines 'efficient cause' as 'active cause' (A
vi, 2, 490; C 472).



Now, Leibniz consistently refers to the causal efficacy or
productivity of substances. Consider the following texts:



> 
> 
> ... the modifications which can occur to a single subject
> naturally and without miracles must arise from limitations and
> variations of a real genus, that is, of a constant and absolute
> inherent nature. (*New Essays* A vi, 6, 65 (1702))
> 
> 
> 
> Anything which occurs in what is strictly a substance must be a case
> of action in the metaphysically rigorous sense of something which
> occurs in the substance spontaneously arising out [*arrive*] of its own
> depths. (*New Essays* A vi, 6, 210)
> 
> 
> 
> ... free or intelligent substances possess something greater and
> more marvelous, in a kind of imitation of God. For they are not bound
> by any certain subordinate laws of the universe, but act by a private
> miracle as it were, on the sole initiative of their own power...
> ("Necessary and Contingent Truths" C 10/PM 100 (1686))
> 
> 
> 
> ... why should God be unable to give substance, from the
> beginning, a nature or an internal force that can produce [*produire*]
> in it, in an orderly way...all the appearance or expressions it
> will have, without the help of any created being? This is especially
> so since the nature of substance necessarily requires and essentially
> involves progress or change, without which it would not have the force
> to act. (*New System* GP iv, 485 (1695))
> 
> 
> 



Whether passive substances truly exist or not, active agencies
"are responsible for whatever activity is attributed to the
former" (Shapere, 45). Leibniz's principle (which has it
ancestors principally in Stoicism) is this: "Whatever is
fundamentally explanatory must be an active principle" (Shapere,
45). The purely passive cannot do anything unless it is acted upon. At
times, Leibniz seems to think that only the truly active exists:
"we can show from the inner truths of metaphysics that what is
not active is nothing, for there is no such thing as a mere
potentiality to act without any initial action" ("On the
True Method in Philosophy and Theology" W 64 (1686)). If all
things that exist are substances, and the essence of substance is
activity, then passive "substances" do not truly exist,
since they are passive, that is, not active (Shapere, 46).



Consider this passage where Leibniz not only attributes causal
efficacy or activity to finite substances, but also causal efficiency
or productivity:



> 
> Bayle asserts, for instance, that by purely philosophical meditations
> one can never attain to an established certainty that we are the
> efficient cause [*la cause efficiente*] of our volitions. But
> this is a point which I do not concede to him: for the establishment
> of this system demonstrates beyond a doubt that in the course of
> nature each substance is the sole cause of all its actions, and that
> it is free of all physical influence from every other substance, save
> the customary cooperation of God. (*Theodicy* SS300)
> 



However, Nicholas Jolley, among others, insists that "[a]lthough
Leibniz may say that it is substances which produce their states, this
is only a loose way of speaking" (Jolley 1998, 605). Strictly
speaking, according to Jolley, *substance* A *caused
perceptual state* p2 is shorthand for *there is some
perceptual state* p1 *such that*
p1 *involves* A *and*
p1 *causes* p2 (Jolley 1998, 605). But
does Leibniz indeed take perceptions or perceptual states to be
efficient causes? The answer is surprisingly unclear. One problem is
that (almost) invariably the language Leibniz employs to describe the
relationship among perceptions or perceptual states is not explicitly
causal (in the efficient or productive sense at least). Leibniz
predominantly uses terms such as '*consequence*',
'*suite*', '*sequitur*',
'*resultat*', '*tend*', and
'*derivantur*', when speaking of the passage from one
perceptual state to another (GP ii 47, 91f, 372; GP iv 440, 521),
terms which should make us hesitate in automatically attributing to
Leibniz a theory of causally efficacious perceptions or perceptual
states. Consider the following representative sample of texts:



> 
> 
> ... every present state of a substance occurs to it spontaneously
> and is only a consequence of [*une suite de*] its preceding
> state. (*Remarks on a Letter to Arnauld*, GP ii, 47)
> 
> 
> 
> Everything occurs in each substance in consequence of [*en
> consequence du*] the first state that God gave it in creating it
> ... (Letter to Arnauld, April 30, 1687, GP ii, 91)
> 
> 
> 
> ... all our future thoughts and perceptions are merely
> consequences [*que des suites*], thought contingent, of our
> preceding thoughts and perceptions (*Discourse on Metaphysics*
> SS14 GP iv, 440)
> 
> 
> 
> ... the present state of each substance is a natural result
> [*consequence*] of its preceding state...
> (*Clarification of Difficulties concerning Monsieur Bayle*, GP
> iv, 521)
> 
> 
> 
> ... every present perception leads to [*que la suite de*]
> a new perception... (*Theodicy* SS403)
> 
> 
> 
> ... subsequent [*perceptions*] are derived
> [*derivantur*] from preceding ones (Letter to Des Bosses, GP
> ii, 372 (1709))
> 
> 
> 



This is just not the kind of language we should expect to find from
Leibniz when speaking of efficient or productive causes. Further, when
Leibniz does claim that perceptions or perceptual states produce other
states, it's difficult to determine if such a claim is to be
taken strictly. Consider these claims:



> 
> 
> And really it can be said that the representation of the end in the
> mind is the efficient cause of the representation of the means in the
> same mind. (*Notes on Stahl* 1702, D ii, 2, 134)
> 
> 
> 
> ... the representation of the present state of the universe in
> the soul of the dog will produce in it the representation of the
> following state of the same universe, just as in objects the preceding
> state effectively produces the following state of the world. In a
> soul, the representations of causes are the causes of the
> representations of effects. (GP iv, 533/WF 78)
> 
> 
> 



Laurence Carlin takes these passages to mean that "deliberation
of means depends on perceptions of ends in the sense that the latter
are the efficient causes of the former" (Carlin, 226). Now,
neither the term "perception" nor "perceptual
state" is used in these passages, but in alignment with
Carlin's interpretation Leibniz defines perception as "the
internal state of the monad representing external objects"
(*Principles of Nature and Grace* SS4) and "the
transitory state that involves and represents a multiplicity in the
unity" (Monadology SS14). One problem with Carlin's
interpretation of these passages, however, is that there is another
passage from the *Theodicy* that may indicate that these
passages are not to be taken strictly:



> 
> When we say that an intelligent substance is moved by the goodness of
> its object, we do not assert that this object is necessarily a being
> existing outside the substance, and it is enough for us that it be
> conceivable: for its representation acts in the substance, or rather
> [*ou plutot*] the substance acts upon itself, insofar as
> it is disposed and influenced by this representation. (*Remarks on
> King* SS21 in *Theodicy*; my emphasis)
> 



This passage can be read to mean that speaking of a substance's
representation acting (as an efficient cause) is only a loose way of
speaking; strictly speaking, it is the substance, or better, power of
the substance, that acts in accordance with this representation
(presumably functioning as a final cause). More on this issue in the
section on final causation, but the main point is that textually it is
difficult to know whether or not Leibniz takes perceptions or
perceptual states to be efficient causes. Of course, all of the texts
adduced up to this point could accommodate the view that for Leibniz
perceptions or perceptual states function as efficient causes, for
while the terms 'consequence' and
'derivantur', for instance, do not entail efficient
causation, they are still compatible with it.



However, the above texts aside, there is a philosophical worry with
attributing efficiency or productivity to perceptions on
Leibniz's metaphysics. The question is whether perceptions can
function as active agencies (and so efficient causes) for Leibniz. In
Leibniz's ontology, what is active is a true, enduring unity and
a center of force--namely, a substance. Leibniz writes that
"everything that acts is an individual substance"
("On Nature Itself" AG 160). To understand perceptions and
perceptual states as causally ordered, in the sense that efficient
causal and not merely lawful or regular or final causal relations
obtain among them, is to subscribe to an *event* oriented model
of causation. But Leibniz, not only like his medieval predecessors but
also many of his contemporaries, subscribes to a rather different
model--one in which a real cause must be a *substance* or
a *power* of that substance. (More on this in the section on
causal models.) Therefore, unless perceptions are genuine substances
and so not events, it seems to follow that for Leibniz, perceptions
(and perceptual states) are causally inefficacious.


## 8. Final and Formal Causation



If Leibniz does not think that perceptions can function as efficient
or productive causes, why does Leibniz even speak of later perceptions
as natural consequences of earlier perceptions, if not causally? There
seem to be two good reasons for this. First, there is a purpose or end
guiding the unfolding of perceptions in each substance. The substance
(or primitive power) acts efficiently in order to fulfill this end.
Such an end may be called a final cause. Second, Leibniz wishes to
ground his Law of Continuity--that all change in nature is
continuous (i.e., in nature there are no gaps). This points to formal
causation in substances. In other words, the picture we come away with
in Leibniz is that a substance's perceptions, representing final
and formal causes, rationally determine that substance's future
states. The object of a perception is a final cause insofar as each
perception specifies why certain states should be produced rather than
others. Perceptions themselves are formal causes insofar as they
specify the content of a substance's future states.



Let's first consider how the objects of perceptions operate as
final causes. Leibniz speaks of perceptual states as unfolding
spontaneously in monads according to a metaphysically basic order of
causal relations. But the fact that perceptions are automatically and
irreducibly causally ordered need only mean that "prior"
perceptions contain the reason for subsequent perceptions. This is the
way Jan Cover puts it: Temporal priority depends on a relation of
"involves a reason for" (Cover, 317). Now, according to
Leibniz, "A reason is a known truth whose connection with some
less well-known truth leads us to give our assent to the latter. But
it is called reason, especially and par excellence, if it is the cause
not only of our judgment but also of the truth itself--which
makes it known as an a priori reason" (*New Essays* A vi,
6, 475). As mentioned earlier, Leibniz also speaks of appetitions as a
substance's "tendencies to go from one perception to
another" (GP vi, 598/AG 207). That perceptions come and go
according to final causes is apparent in the following passage from
the *Principles of Nature and Grace* SS3:
"perceptions in the monad arise from one another by the laws of
appetites, or by the laws of the final causes of good and evil, which
consist in notable perceptions, ordered or disordered" (GP vi,
598/AG 207). Leibniz writes in the same work: "the future can be
read in the past; the distant is expressed in the proximate" (GP
vi, 605/AG 211). The moral is that perceptions function as
teleological explananda, which is reminiscent of Aristotle's
account of final causation, where natural processes are completed and
regulated by a final state or end, towards which they tend.



It is also worth noting that Leibniz does not limit his doctrine of
final causation to the conscious activity of rational agents, for he
holds that a mental state can function as a final cause without our
being aware of it. In a letter to Sophie Charlotte, Leibniz writes:
"So that even in our instinctive or involuntary actions, where
it seems only the body plays a part, there is in the soul an appetite
for good or an aversion to evil which directs it, even though our
reflection is not able to pick it out in the confusion" (GP III,
347; WF 224f.). Nor does Leibniz restrict final causation to rational
agents. (Nor does Aristotle for that matter.) The final cause of a
plant or an animal is not a plan or intention. Rather, it is whatever
lies at the end of the regular series of developmental changes that it
undergoes. 



Let's now explain the presence of formal causation in
perception. Some thinkers contemporaneous with Leibniz, most notably
Pierre Bayle, found the apparent lack of continuity among our
perceptions to be deeply problematic. We are often genuinely surprised
by the content of our perceptions, some of which seem utterly
disconnected from and radically unlike prior perceptions. But, given
the Law of Continuity, Leibniz cannot allow perceptions to arise in a
monad that are radically unlike preceding perceptions. To solve this
problem, Leibniz offers his theory of petites or unconscious
perceptions and says that this apparent lack of continuity in the
actions of the individual substance results from our overlooking the
complex multitude of unconscious perceptions, which flow, at every
moment, from the individual's nature. But the doctrine of petite
perceptions alone is not sufficient to ground continuity. Rather, it
is the rational relation among perceptions that serves to guarantee
continuity in perceptual content. Leibniz speaks of the "marks
[*les marques*]" that each perception of a substance
contains for all other perceptions that substance will ever have
(*Discourse on Metaphysics* SS8). I take it that this
relation among perceptions points to perceptions being formal causes;
that is to say, a substance's present states specify fully the
content of its future states.



So, to summarize, what causes the changes in perceptions? Three
species of cause: efficient causes (in accordance with laws of mind
and active forces), final causes (in accordance with the law of
appetites and ultimately God's aim of universal and maximum
harmony), and formal causes (in accordance with the Law of
Continuity). Leibniz's account of intrasubstantial causation
therefore involves a tight connection between efficient, final, and
formal causes. This should not be surprising, since Leibniz tells us
that "[a] cause in the realm of things corresponds to a reason
in the realm of truths, which is why causes themselves--and
especially final ones--are often called reasons" (*New
Essays* A vi, 6, 475).



None of this should be surprising. Hume may have endorsed just one
species of cause--efficient--but final and formal causation
did not die with the advent of mechanistic science and philosophy in
the seventeenth century. Besides Leibniz, Gassendi, Boyle, and Newton
all accommodated final or teleological causation in their systems.
Spinoza is really the only known philosopher in the seventeenth
century who truly has no place for final causation in his philosophy,
except in the sense that artifacts have final causes (e.g., chairs
serve a purpose and carpenters create them in part to achieve that
purpose). On the other hand, Spinoza probably does endorse formal
causation in his metaphysics of substance.


## 9. Causal Models



It has been noted that "[p]erhaps the greatest difference
between a contemporary concept of causation and a seventeenth century
concept is one of model. Following in Hume's footsteps,
contemporary philosophers customarily conceive causation as a relation
between events (e.g., my flipping the switch caused the light to come
on) while seventeenth century philosophers thought of it more as a
relation among substances, their qualities, and their
'powers' (e.g., I cause my idea of justice)"
(Frankel, 57).



Yet this early model of causation possesses at least one virtue that
the contemporary one does not. It has the distinct advantage of
avoiding any problematic regress of causal explanation. Once a causal
sequence of events is laid out, we can always ask why that sequence,
and not another, occurred. But an explanation of this sequence,
according to an event/event model of causation does not preclude the
same question "Why that sequence of events?" being asked
of it again and again. On the other hand, Leibniz does not think that
the power or will, which are not events at all, but faculties, of an
agency or agent, need any explaining. The regress of explanation stops
abruptly with the substance. In a letter to De Volder (June 30, 1704),
he writes: "To ... ask why there is perception and appetite
in simple substances is to inquire about something ultramundane, so to
speak, and to demand reasons of God why he has willed things to be
such as we conceive them to be" (GP ii, 271/L 538). Furthermore,
the central message of Leibniz's essay, *Against Barbaric
Physics* (c. 1713), seems to be that since the actions of
substances are in fact spontaneous, there is no way of explaining
change in monads unless we posit some force or power that drives
substantial action. If it turns out that substances just are forces or
powers, as Julia Jorati and John Whipple maintain, it is no violation
of this causal model. At any rate, without this agency in monads,
there would be no cause sufficient to determine the whole sequence of
events and thus no adequate causal explanation of the totality of
actions (i.e., perceptions) on the part of substances. And, besides
failing to break out of the cycle of explanation that appears to
plague event/event models of causation, such a picture appears to
violate Leibniz's Principle of Sufficient Reason:



> 
> Thus the sufficient reason, which needs no other reason, must be
> outside this series of contingent things, and must be found in a
> substance which is its cause, and which is a necessary being, carrying
> the reason of its existence with itself. Otherwise, we would not yet
> have a sufficient reason where one could end the series.
> (*Principles of Nature and Grace* SS8 GP vi, 604/AG 210)
> 



Hence, we should understand Leibniz's statement in a letter to
Arnauld (May 1686) that "there is always something to be
conceived in the subject which provides the explanation why this
predicate or this event belongs to it, or why a particular event
happened rather than not" (GP ii, 45/PM 60) not in terms of some
ideal event contained in the subject as carrying the correlative
explanatory role, but the power or principle of change of the
subject.



Further lending credence to the claim that Leibniz postulates a
substance-accident model of causation, it appears that whenever
Leibniz describes the causal relation found within substances, even
those depictions that are best understood as metaphorical, those
depictions themselves point to a non-homogeneous account of the
intrasubstantial causal relata. That is, intrasubstantial causal
relata do not involve components of the same kinds. Whether he speaks
of the actualizations of an essence, predicates of a subject, values
of a function, perceptions of an appetite, cogitations of a will, ends
of reason, harmonies of a rule of order, it is clear that Leibniz
envisions "effects" which are different in kind from their
"causes." The essence of a substance is not itself an
actualization; the function of a substance is not itself a value of a
function (Cover & O'Leary-Hawthorne, 229); a
substance's appetite is not itself a perception; the will of a
substance is not itself a cogitation, it is a faculty; the reason
governing the substance is not itself the end to which it strives;
and, the rule of order is not itself an instance of the harmonious
agreement among substances.



All told, it seems that Leibniz ascribes to a heterogeneous account of
causation, where the cause is different in kind from its effect.
Ultimately, Leibniz offers a theory of intrasubstantial causation that
incorporates both efficient, final causes, and formal causes, where
only substances--or better yet, their powers--can be
efficient causes and perceptions have a teleological as well as a
formal function.



Taking substances as paradigmatic causes may help us to better
appreciate Leibniz's compatibilist account of freedom. Except
for divine activity, all genuine causation takes place
intrasubstantially--that is, *within* a substance.
Substances are the causes of their future states and determine those
effects. However, knowing that a substance's future states flow
with certainty from prior states due its own inherent powers does not
automatically entail that all of its states are absolutely
*essential* to it. That I must write this entry on
Leibniz--given my initial states, it was certain or determined
for me to write it--does not entail that it is part of my
essence, my very identity, to write this entry. Leibniz wants to
maintain that I could have acted otherwise. And thus I freely wrote
it, even though it was certain that I did so. 


## 10. Conceptual "Outline" of Leibnizian Causes



Leibniz's theory of causation incorporates a variety of
causes--some would say a confusing array of causes. To help
dispel this confusion, an outline of the various Leibnizian causes may
be helpful.



I. Real Causes (Only a substance can be a real cause; that is, effect
changes in itself or in another noumenally (*New Essays*
65).)


1. Intersubstantial (In which a substance operates transiently or
beyond itself. A substance acts on another to cause change; it effects
changes in the states of others.)
	1. Productive of a natural state (Such acts of God sustain the active
	force in the monad (*Monadology* 47).)
		1. Conservative efficient (God contributes being or perfection to a
		substance, analogous to the way in which we produce our thoughts
		(*Discourse on Metaphysics* 14). This is continual and
		non-draining. God's conservation is also special, not general
		(*Theodicy* 27).)
	2. Productive of a miracle (Such acts of God "surpass all the
	force of creatures" (*Theodicy* 249).)
		1. Creative efficient (God chooses to actualize the most perfect set
		or totality of compossible substances (*New System* 4).
		"God produces substances from nothing" (*Theodicy*
		395).)
	3. Non-productive (That which rationally determines a
	substance's future states.) a. Final (God's reasons to
	produce, based on the formal and final causes of created substances
	and the Principle of the Best.)
2. Intrasubstantial (In which a substance causes change in itself; it
effects changes in its own states. "Each substance is the true
and real cause of its own immanent actions ... sustained by
divine concurrence" (A vi, 4).)
	1. Productive (To produce a state is to efficiently cause it (WF 56f;
	*Theodicy* 298).)
		1. Efficient (An efficient cause happens in accordance with formal
		and final causes.)
		2. Final (What a substance's present states specify about its
		future states, in terms of why these future states rather than others.
		Some argue that final causes can be productive (e.g., Carlin
		2006).)
	2. Non-productive (That which rationally determines a
	substance's future states. A reason-giving cause that is
	explanatorily prior to the efficient cause.)
		1. Formal (What a substance's present states specify about its
		future states, in terms of content.)
		2. Final (What a substance's present states specify about its
		future states, in terms of why these future states rather than
		others.)
			1. Free (When acting, the bearer of a final cause is aware of that
			cause.)
			2. Unfree (When acting, the bearer of a final cause is not aware of
			that cause.)