Descartes on the causal powers of bodies without substantial forms
Kara Richardson
Draft for UNYWEMP, Sunday Oct. 4, 2009
One major difference between Descartes and his Aristotelian predecessors is his rejection of
substantial forms.1 According to some of his interpreters, this rejection deprives bodies of causal
powers. Daniel Garber puts the point this way:
For the schoolmen, the world God sustains is a world of matter and substantial forms. These forms
are active principles that constitute an important class of the mediating causes of change that the
schools recognized. But in a physical world whose only constituents are extended bodies, a world
without forms (at least if we set aside human souls), then this class of mediating causes is not
available to press into service. What Descartes chooses in their place is God, who will act not only
as the general conservator of the world, but as the direct cause of motion and change in that world.2
The view that Descartes’ rejection of Scholastic substantial forms deprives bodies of causal powers
depends in part on the claim that these forms are active principles. But this claim is ambiguous. Is
the substantial form of a substance a direct source of motion and change? In other words, does a
substantial form make an efficient causal contribution to substantial activity? Or does it contribute to
activity indirectly, by determining the characteristic features and behaviors of a member of some
1
The claim that Descartes rejects substantial forms must be qualified in two ways. First, Descartes
sometimes refers to the mind as the form of the human body or as the form of the human being,
e.g., at CSM II 246/ AT VII 356, CSM III 207 /AT III 503 and CSM III 208/ AT III 505).
Scholars disagree about whether his use of Aristotelian language in this regard indicates that he
endorsed a hylemorphic account of the unity of a human being. Hoffman (1986) argues in favour of
this view; Rozemond (1998), ch. 5 argues against it. Second, Marleen Rozemond has shown that
Descartes’ notion of a principal attribute is a successor to substantial form in the sense that “the
principal attributes of extension and thought determine the kinds of modes found in bodies in
general and in minds” (Rozemond (1998), p. 117). In this way, it play a role similar to that of a
substantial form which determines the proper accidents of a substance, e.g., the substantial form of
water determines its proper accidents, sc., coldness and moisture.
2
Garber (1992), pp. 274-5. Garber makes the same point in several other works; see Garber .Gary
Hatfield also makes this point; see Hatfield (1979), p. 113. Michael Della Rocca thinks that
Descartes’ denial of substantial forms conflicts with his attribution of causal powers to bodies, but
defends Descartes; see Della Rocca (1999).
1
natural kind? In other words, does the explanatory value of a substantial form stem solely from its
role as the formal cause of a material substance? Both of these accounts of the relationship between
substantial forms and substantial activity appear in secondary literature on causation in Late
Scholastic and Early Modern philosophy, but they are not distinguished.3 One aim of this paper is
to show that the Scholastics themselves disagreed about the contribution of substantial forms to
substantial activity. A second aim is to show that their disagreements inform Descartes’ view of the
causal powers of bodies.
This paper has three parts. I focus first on Scholastic debates about the contribution of
substantial forms to substantial activity as reported by Suarez in his Metaphysical Disputations. Suarez
3
In a recent article, Robert Pasnau argues that emphasis on the concrete, causal roles of substantial
forms (as opposed to their abstract, metaphysical roles) is distinctive of the Scholastic notion of
substantial form. See Pasnau (2004), pp. 35-39. He discusses some cases in which substantial forms
were held to play direct efficient causal roles; e.g., he mentions Ockham’s and Suarez’s view that the
substantial form of water is the cause of heated water’s reversion to coldness (Pasnau (2004), pp. 3738). Nevertheless, he summarizes the concrete, causal side of the Scholastic doctrine of substantial
form as follows: “[i]n all these texts, the dominant conception of form is decidedly concrete rather
than metaphysical. Substantial forms are understood as causal agents that would figure centrally in
any complete scientific account of the natural world. They explain why water is cold, why gold is
heavy, why horses have four legs and human beings two, and why horses merely whinny whereas
human beings talk” (Pasnau (2004), p. 39). This summary suggests the view that substantial forms
contribute to substantial activity indirectly, by determining the characteristic features and behaviors
of a member of some natural kind.
Garber identifies substantial forms as “active principles” and as “mediating causes” in the
above cited passage from Descartes’ Metaphysical Physics, which suggests that they play efficient causal
roles. But earlier in the book, he provides an account of the relationship between substantial forms
and substantial activity which mentions only their indirect role: “substantial form is that from which
the characteristic behavior of the various sorts of substances derives, and thus that in terms of which
their behavior is to be explained” (Garber (1992), p. 95). The latter kind of account is fairly
common. For example, Steven Nadler claims that “[t]he substantial form of the substance is that
from which its essential properties and characteristic behaviours derive. All motion and change, all
causal and other powers are to be explained by reference to the specific form inhering in (and
individuating) a parcel of matter” (Nadler (1993), pp. 2-3). A similar account is offered by
Rozemond (1998), pp. 104-5. A few scholars fairly clearly identify substantial forms as efficient
causes. For example, Cees Leijenhorst writes that “according to the Aristotelians, forms are intrinsic
principles of motion. The substantial form of an “earthly” body explains why and how it strives to
the centre of the earth” (Leijenhorst (2002), p. 138). A similar account is offered in Van Ruler
(1995), pp. 134-6.
2
himself defends a robust account of the efficient causality of substantial forms. He argues that
substantial forms contribute directly to substantial activity in several cases. And he contrasts his
view with that of “Thomist” Aristotelians who hold that the influence of substantial forms on
substantial activity is limited to their roles as formal causes. For the latter Aristotelians, substances
act directly through their accidents, not their substantial forms.
In the second part of the paper, I show that Descartes responds to the Scholastic debates
about the relationship between substantial forms and substantial activity in his letter to Regius of
January 1642. I argue that he there sides with those Aristotelians who hold that the actions of
substances depend directly on their accidents alone, and I argue that this letter reveals Descartes’
own view of the causal powers of bodies without substantial forms. Rather than replacing
substantial forms with God to explain activity in the created world, Descartes reforms the ground
for activity in the created world, by replacing Aristotelian active qualities with Cartesian ones. In the
final part of the paper, I consider an important objection to my interpretation, sc. that it conflicts
with Descartes’ view that the nature of body is extension.
1. Suarez on substantial forms as efficient causes
Scholastic substantial forms have their roots in Aristotle who claims that among the causes
of something are its form, i.e., the definition of its essence (Physics 194b 27-28). To know the form
of a thing is to know what kind of thing it is. This contribution to knowledge is quite different from
the one made by an efficient cause, i.e., by “the primary source of the change or rest” (Physics 2.3
194b 30-32). To know the efficient cause of a thing is to know the mover or shaper who makes it
happen or brings it to be. Nevertheless the two types of cause intersect: what kind of thing X is
determines for the most part what changes X can bring out or suffer. Efficient causal powers are
rooted in the substantial forms of agents, and their exercise depends on passive powers which are so
rooted in patients. For example, the rational soul – the substantial form of human being –
3
determines our powers to nourish ourselves and grow, to reproduce, sense, move about, imagine
and understand. These powers are either active or passive, and Scholastic philosophers disagreed
about which were which: for example, Aquinas held sensation to be a passive power acted on by the
object of sense, e.g., sight is a passive power acted on by colour, whereas Suarez held it to be an
active power on the ground that sensation requires attention on our part. But they agreed on the
general point that the substantial form of a substance determines what it can do or suffer. Viewed
from this perspective, substantial forms play a role in natural action, but this role is indirect.
The view that substantial forms play direct efficient causal roles was controversial in the
Middle Ages. Suarez holds that they do in at least two kinds of ways.4 First, he argues that a
substantial form is the efficient cause of accidents appropriate to it, e.g., an animal soul is the
efficient cause of the powers of sensation and locomotion, which are accidents appropriate to an
animal soul.5 Likewise, the substantial form of water is the efficient cause of the reversion of heated
water to coldness, which is an accident appropriate to the watery form. Second, substantial forms
make direct efficient causal contributions to substantial activity. For example, the soul has a direct
4
My account focuses on Suárez’ discussion of efficient causality in Disputationes Metaphysicae (DM)
17-19 and on his discussion of formal causality in Disputationes Metaphysicae 15. Disputations 17-19
are available in English translation by Alfred Freddoso: Suárez, Francisco. On Efficient Causality:
Metaphysical Disputations 17, 18, and 19, trans. Freddoso. New Haven: Yale University Press, 1994.
Disputation 15 is translated into English by John Kronen and Jeremiah Reedy: Suárez, Francisco.
On the Formal Cause of Substance: Metaphysical Disputation XV, trans. Kronen and Reedy. Milwaukee:
Marquette University Press, 2000. Unless otherwise noted, quotations of Suárez in English are taken
from these translations.
5
DM 15.1, DM 18.3. In DM 15.1, Suarez uses the example of water to support the claim that we
must posit substantial forms. He says “if water, for example, is heated, and later the external cause
of the heat is removed, the water returns to its original coldness because of an intrinsic force, as
experience attests. This is a sign, therefore, that there is in water a certain inner principle from
which an increase of cold flows anew after all external obstacles have been removed. That principle
which returns water to its original temperature, however, cannot be anything other than the
substantial form” (DM 15.1, Kronen (trans.), p. 22). Suarez continues by refuting alternative
explanations of this phenomenon, which do not employ the claim that the principle which returns
water to its original temperature is the substantial form (DM 15.1, Kronen (trans.), pp. 22-25). He
cites the example of water in DM 18.3 as support for the claim that “the substantial form has a
certain power for having its proper accidents emanate from it” (DM 18.3, Freddoso (trans.), p. 93).
4
influence on vital actions, including relatively lowly ones such as digestion, as well as nobler acts
such as sensation and, in the human case, intellection.6 And substantial forms are direct efficient
causes of the generation of new corporeal substances. In all of these cases, Suárez defends the view
that substantial forms play genuine efficient causal roles against “Thomist” Aristotelians, who
attribute to substantial forms roles that fall short of genuine efficient causality. I will focus primarily
on the last of these cases – sc., the causal role of substantial forms in generation – because Suárez’
discussion of it is especially instructive with respect to the difference between his own robust view
of the efficient causality of substantial forms and the different view of his opponents.
In Disputationes Metaphysicae 18.2, Suarez aims to determine the principle by which one
substance generates another, i.e., he aims to determine which of X’s metaphysical constituents – sc.,
form, matter and accidents – is that in virtue of which X generates Y.7 Suarez rules out matter
immediately, since matter itself is nonactive. He then argues that no accident is a principal principle
of a substance:
a principal cause must be either more noble than, or at least no less noble than, the effect. For since
no one gives what he does not have, how can an imperfect form have within itself or communicate
to its suppositum a principal power for effecting a more perfect form, a form which it is unable to
contain either formally or eminently? But an accidental form is more imperfect than a substantial
form. Therefore, an accidental form cannot be a principal principle for educing a substantial form.8
The argument depends on a causal principle familiar to readers of Descartes’ Third Meditation: the
effect cannot be more perfect than the cause. It also relies on an ontological hierarchy in which
6
DM 18.5.
More precisely, he discusses the principle by which one created substance generates another. Suarez
is here concerned with the causal powers of creatures in cases of substantial generation. He aims to
defend the view that new substances are educed from the potency of matter through natural
processes. His main target is Avicenna’s view that new substantial forms are bestowed by a separate
intelligence (DM 18.1, pp. 597-98, Freddoso (trans.), pp. 48-49). He attributes a view of this sort to
Plato, Philoponus and Themistius as well. Philoponus is said to identify the form-giver as “the
Universal Craftsman of nature”; Themistius is said to identify it as “the world soul” (DM 18.2, p.
602, Freddoso (trans.), p. 60).
8
DM 18.2, p. 599; Freddoso (trans.), p. 52.
7
5
substantial forms – e.g., George the monkey’s soul – are more perfect than accidental ones, e.g.,
George’s height, weight etc. Finally, it assumes that in generation, a new substantial form is educed
from the potentiality of matter by some agent or agents. The causal principle, coupled with the
ontological hierarchy, yields a fairly simple argument against the view that the generation of a new
thing could be the work of accidents alone: since accidents are less perfect than substantial forms,
they cannot by themselves effect substantial forms.9 Note that Suarez holds the conclusion of the
argument – sc., that no accident is a principal cause of a substance – to be uncontroversial: he says
that “[o]n this almost everyone agrees”.10 This could be due to the influence of the argument itself,
9
Suarez’ claim that no accident is a principal efficient cause of a substance is compatible with his later
claim that accidents are instrumental causes in cases of substantial generation. In brief, he holds that
accidents play genuine efficient causal roles in generation as instruments of the principal principle of
generation, i.e., the substantial form of the generator. Suarez distinguishes a principal efficient cause
from an instrumental efficient cause in DM 17.2. He defines a principal cause as “a cause which
through a principal power – that is, a power that is more noble than, or at least as noble as, the
effect – influences the action whereby such an effect is produced (DM 17.2, p. 591; Freddoso
(trans.), p. 30). A principal cause operates “through its own power, not only because it has an
intrinsic and innate power to act but also because it has a power that is per se proportionate to the
effect and does not stand in need of any elevation” (Ibid.). An instrument “is said to operate ‘in the
power’ of the principal agent” not because it doesn’t require its own intrinsic power, but rather
because its intrinsic power “is not proportionate or sufficient, and the instrument has the ability to
operate only according to the measure of the principal agent’s power and elevation” (DM 17.2, p.
591; Freddoso (trans.), p. 31). To illustrate the distinction Suarez uses the stock example of a saw,
which is an instrumental cause of an artifact produced by a craftsperson who uses the saw as her
tool. One problem with the example is that it is easy to overlook the fact that genuine causal power
is attributed to instruments, e.g., the power to cut is attributed to the saw. The saw is an
instrumental cause only with respect to the production of the artifact produced by the craftsperson; it
is more like a principal cause with respect to cutting. Suarez puts the point as follows: “[a] saw, for
instance, is an instrument for making a given artifact. By striking the middle parts [of the wood] and
moving them locally, this instrument proximately effects only a division [of the wood] and is related
to this effect more as a principal cause. But what results from this in the form of the artifact, to
which the saw is related as an instrumental cause. For it does not attain to this form immediately by
its own action; rather, the form merely results from the prior effect”(MD 17.2, p. 587; Freddoso
(trans.), p. 30).
10
DM 18.2, p. 599, Freddoso (trans.), p. 52. He continues as follows: “[f]or even though John
Major, Sentences 4, dist. 12, is commonly cited in favor of the contrary opinion, he does not deny this
point; nor does anyone else I have looked at (Ibid.).
6
which is not original to Suarez. It appears at least as early as Aquinas’ De Potentia, where it is
presented as an objection to his claim that corporeal agents can generate new corporeal substances.11
Since Suarez has ruled out both matter and accidents as candidates for the role of the
principal principles by which one created substance produces another, he concludes that this role
must be played by the substance’s substantial form. He holds this conclusion to be uncontroversial
as well, in part because “once an enumerative induction has been made, nothing else remains” and
also because it too “seems to be accepted by the common consensus of everyone”.12 But Suarez’
report of consensus in these matters elides an important dispute about “the way in which the
substantial form is a principal principle” in generation.13 This dispute has to do with whether the
11
In De Potentia 3.8, Aquinas raises and responds to the following objection to his claim that natural
agents generate their progeny. The objection employs the claim that the active principles of natural
agents are accidents, e.g., fire acts by heat, which is an accident. The objector argues that since an
effect cannot excel its cause, and since a substantial form excels an accident, an accident cannot be
the active cause of a substantial form (Aquinas. De Potentia 3.8, Marietti 9th rev. ed., vol. 2, p. 60;
Dominican Fathers (trans.), Book 1, p. 138). Aquinas argues in response that since “[a]n accidental
form acts by virtue of the substantial form whose instrument it is…it is not unreasonable if the
action of an accidental form terminate in a substantial form” (Ibid.). In other words, when fire is
generated by fire, the heat of the generating fire acts in virtue of its substantial form and for this
reason is up to the task of bringing about a new substance. In DM 18.2, Suarez argues that this
response succeeds only if substantial forms are genuine efficient causes of generation. Aquinas’
claim in De Potentia 3.8 that an accidental form acts by virtue of the substantial form (in virtute formae
substantialis) is ambiguous with respect to this issue. We will see that Suarez attributes to Thomists in
general the denial that substantial forms are genuine efficient causes.
12
DM 18.2, p. 599; Freddoso (trans.), p. 52. The reason Suarez cites for this consensus is the
principle that operation follows upon esse: since this is so and “since the substantial form is the
principal act of the suppositum and that which principally gives it esse, it must also be the principal
principle of operating” (Ibid.). Freddoso notes that the principle that operation follows upon esse is a
“scholastic adage” (Ibid., n. 6). Is this the same principle which grounds Aquinas’ argument for the
subsistence of the human soul in Summa Theologiae 1.75.2? Aquinas argues there that only what
subsists per se can operate per se on the ground that “as a thing operates, in that way it is” (Aquinas.
Summa Theologiae 1.75.2, p. , Pegis (trans.), p. 685). Since the human intellect performs an operation
per se – sc., understanding – it follows that the human intellective soul subsists per se.
13
DM 18.2, p. 599; Freddoso (trans.), p. 53.
7
substantial form has an immediate influence in generation or whether it has “only a remote and, as it
were, originating influence”.14
Suarez himself argues that the substantial form has an immediate influence in generation.
He attributes the alternative view – sc., that the substantial form has a merely remote and originating
influence – to the Thomists, but he also says that it “seems to be the common position of the
Peripatetics” and cites Aristotle, Alexander of Aphrodisias and Averroes as its proponents.15 One
argument for the alternative view relies on the claim that “a substantial form is not per se immediately
active but is instead active through a power, which is a quality distinct from it”.16 This claim is
evident by induction: “we see that any substance whatsoever uses accidents for all its other
actions”.17 And it derives support from the following argument: “a substantial form is of itself
determined only to giving esse as a formal cause, whereas with respect to its actions it is an
indeterminate principle, since it is almost always able to effect several actions to which it is
determined by its accidents”.18
In these arguments, the contribution of a substantial form to the actions of a substance is
restricted to its role as a formal cause which gives being to the composite. The substance’s actions
are achieved by means of its accidents. Experience confirms the latter claim, but it can also be
deduced from the fact that the form itself is not determined to any one action. For example, a
maple tree has the powers to nourish itself and to grow, to produce seed and to produce sap. Its
substantial form makes it be by making it be something, namely, a maple tree. And the various
powers of the maple tree are powers which it has in virtue of what it is. But since the substantial
form confers upon this substance a variety of powers, the substantial form is not itself determined
14
DM 18.2, p. 599; Freddoso (trans.), p. 53.
DM 18.2, p. 601, Freddoso (trans.), p. 58.
16
DM 18.2, p. 601, Freddoso (trans.), p. 59.
17
DM 18.2, p. 602, Freddoso (trans.), p. 54.
18
DM 18.2, p. 601, Freddoso (trans.), p. 59.
15
8
to any one action (apart from the act of giving being). Rather, the accidents of the maple tree are
determined to specific actions. So, properly speaking, the accidents of the maple tree, not its
substantial form, are the immediate principles of its activities.
Suarez’s argument against the alternative view depends in part on the claim that his
opponents attribute to the substantial form an influence which falls short of genuine efficient
causality. He argues for this claim as follows:
Nor is it sufficient to reply that efficient causality is attributed to [substantial] forms because the
qualities through which alone they exercise all their actions emanate from them. For, as we
explained above, this is not proper and per se efficient causality but rather only remote and
originating efficient causality, since an action that arises immediately from an accidental form alone
likewise depends per se and essentially on it alone as on a proximate principle. (I am here leaving to
one side the concurrence of a universal cause.) An indication of this is that if God conserves, say,
the heat [without the fire], then every action that proceeds proximately just from the heat can be
conserved, too – as the authors of the contrary position also acknowledge. Therefore, this is an
indication that the substantial form is not a per se principle of any such action.19
Suarez’s claim that “remote and originating efficient causality” is not genuine efficient causality is
persuasive. But it is not immediately clear that this argument serves as support for his view that
substantial forms play genuine efficient causal roles. Couldn’t his opponents simply embrace the
denial that substantial forms are efficient causes? After all, it seems obvious that heat conserved
apart from the fiery form will scorch, melt, blacken and so on just as well as heat conserved with the
fiery form. In that case, there is no need to attribute an efficient causal role to substantial forms.
Suarez discounts this response due to the problem at hand, sc., that if substances act by their
accidents alone, then they are without any principle sufficient for generation: remember, the lower
can’t effect the higher. The claim that substantial forms are genuine efficient causes safeguards the
view that generation occurs through natural processes.20
19
DM 18.2, Freddoso (trans.), p. 71.
But the claim isn’t necessarily ad hoc. As mentioned earlier, Suarez holds that substantial forms
play efficient causal roles in a variety of cases. The scope of their efficient causal contributions is
probably a source of Suarez’s confidence in his own view. I do not mean to suggest that I think that
20
9
Whether or not Suarez can succeed against his Thomist and Peripatetic opponents need not
be determined here. I want instead to focus on a view of the causal powers of bodies which his
argument against these opponents suggests. Suarez claims that qualities or accidents conserved (by
God) apart from substantial forms will do whatever they do when conserved with these forms.
Suarez illustrates his point with the example of heat, a single quality. But there is no reason why
God couldn’t conserve collections of qualities or accidents apart from the substantial forms which
are supposed to give rise to these collections in nature.21 Say God conserves the tart, white flesh of
the apple apart from its form. It is clear, Suarez thinks, that these qualities would act on our senses
in just the way they do when conserved with the form of apple.22 This account of the actions of
qualities or accidents conserved by God apart from substantial forms suggests that bodies without
substantial forms could have causal powers, and that the ground for these powers would be qualities
or collections of qualities. In the next Section, I will argue that Descartes adopts a similar view.
Suarez’s identification of substantial forms as efficient causes is justified. This issue requires a more
detailed treatment than I can offer here.
21
God conserves collections of accidents apart from substantial forms in the mystery of the
Eucharist, i.e., he conserves the accidents of wine and bread apart from their substantial forms.
Thus, one of the questions Suarez must determine in DM 18.2 is whether the separated accidents of
wine and bread act apart their substantial forms. He thinks that it is obvious that they do; however,
he denies that the separated accidents of wine have sufficient power to convert a drop of water into
wine. Such a conversion is a substantial generation and requires the aid of a higher power (DM
18.2.29, Freddoso (trans.), p. 77).
22
What, then, is the difference between a collection of qualities and a collection of qualities plus a
substantial form? According to Suarez, one difference is that a collection of qualities lacks the unity
which is required to constitute a natural thing (DM 15.1.7). Another is that the substantial form
which unites the collection may also be needed for cooperative efforts amongst members of
collection. For example, Suarez argues that the various powers of my human soul, e.g., sight,
imagination and understanding, cannot interact with one another directly. Their apparent
interaction requires that they are “connected in some common principle” – sc., my soul – which is
the substantial form of my body (DM 18.5.3, Freddoso (trans.), p. 123). This aspect of the efficient
causality of substantial forms is the focus of Marleen Rozemond’s “Suarez and the Unity of
Consciousness” (2008). So Suarez identifies interesting and important differences between
aggregates and aggregates unified by substantial forms.
10
2. Descartes on substantial forms and activity
Descartes most often attacks the Scholastic doctrine of substantial forms by arguing that we
do not need to posit them in order to explain natural phenomena. We see this strategy at work in
his account of how flame burns wood in his early physical treatise, The World. There he says:
When flame burns wood or some other similar material, we can see with the naked eye that it sets
the minute parts of the wood in motion and separates them from one another, thus transforming
the finer parts into fire, air and smoke, and leaving the coarser parts as ashes. Others may, if they
wish, imagine the form of fire, the quality of heat, and the process of burning to be completely
different things in the wood. For my part, I am afraid of mistakenly supposing there is anything
more in the wood than what I see must necessarily be in it, and so I am content to limit my
conception to the motion of its parts.23
The conclusion of this attack is of course compatible with the existence of substantial forms, and
Descartes does not claim that there are no substantial forms.24 One of the reasons Descartes cites
for his adoption of this strategy is political: he thinks that to deny substantial forms is to court
controversy. So he admonishes his disciple Regius for openly rejecting them:
Do you not remember that on page 164 of my Meteorology, I said quite expressly that I did not at all
reject or deny [substantial forms] but simply found them unnecessary in setting out my explanations?
If you had taken this course, everybody in your audience would have rejected them as soon as they
saw they were useless, and in the mean time you would not have become so unpopular with your
colleagues.25
Given the uproar at the University of Utrecht which followed Regius’ decision openly to reject
substantial forms, the political reason for Descartes’ less confrontational approach appears to have
been well-founded. Nevertheless, Descartes comes to the aid of his beleaguered student in his letter
of January 1642 which marshals arguments Regius can use against his Aristotelian opponents.
In one of these arguments against substantial forms, Descartes exploits the terms of
Scholastic debates about the causal roles of substantial forms. He says,
[i]t would certainly be absurd for those who believe in substantial forms to say that these forms are
themselves the immediate principle of their actions; but it cannot be absurd to say this if one does
23
CSM I 83/AT XI 7.
24
Garber, Rozemond
25
CSM III 205/AT III 492.
11
not regard such forms as distinct from active qualities. Now we do not deny active qualities, but we
say only that they should not be regarded as having any degree of reality greater than that of modes;
for to regard them so is to conceive of them as substances. Nor do we deny dispositions, but we
divide them into two kinds. Some are purely material and depend only the configuration or other
arrangement of the parts. Others are immaterial or spiritual, like the states of faith, grace and so on
which theologians talk of; these do not depend on anything bodily, but are spiritual modes inhering
in the mind, just as movement and shape are corporeal modes inhering in the body.26
Here Descartes rejects as absurd the view that Scholastic substantial forms are immediate principles
of their action, and claims that the absurdity of this view is avoided by those who conflate
substantial forms with active qualities. Thus there is absurdity in holding that active qualities are
immediate principles of their actions. And Descartes himself embraces active qualities and
dispositions. While the terms “active quality” and “disposition” are Aristotelian in origin, Descartes
does not mean to suggest that he agrees with his predecessors about the character or nature of these
things. For example, while Aristotelians of all stripes consider heat an active quality, Descartes
considers it an obscure sense impression which arises in part from the size and speed of bits of
matter and in part from an idea in the mind. But he does mean to suggest that he holds that created
substances have active powers, so long as these are understood to be modes.
By rejecting the view that substantial forms are immediate principles of action, and by
identifying active qualities as the direct principles of substantial activity, Descartes affirms one of the
Scholastic views mentioned above, namely, that substances act through their accidents alone. For in
Scholastic ontology, active qualities are accidents. Descartes’ letter to Regius indicates that he
considers his denial of substantial forms to be compatible with the claim that bodies have causal
powers. So this letter tells against Garber’s claim that Descartes replaces substantial forms with God
as the direct source of motion and change in the created world. And it illuminates Descartes’ view
of the ground of activity in bodies without substantial forms. His view echoes a Scholastic model,
26
CSM III 208/AT III 503-4.
12
which Suarez illustrates in his example of the action of the active quality heat when conserved apart
from the fiery form. On this model, activity in the created world depends on accidents alone.
Descartes employs the model on several occasions. One prominent example is his account
of how fire burns wood in Le Monde. There he argues that in the absence of the form of fire and the
quality of heat, that is, in the absence of those entities which ground Scholastic causal powers, the
changes we observe when wood burns could be caused by “some power which puts its finer parts
into violent motion and separates them from the coarser parts”.27 He then explains what constitutes
this power in the body of the flame:
Now since it does no seem possible to conceive how one body could move another except through
its own movement, I conclude that the body of the flame which acts upon the wood is composed of
minute parts, which move about independently of one another with a very rapid and very violent
motion. As they move about in this way they push against the parts of the bodies they are touching
and move those which do not offer them too much resistance. I say that the flame’s parts move
about individually, for although many of them often work together to bring about a single effect, we
see nevertheless that each of them acts on its own upon the bodies they touch. I say, too, that their
motion is very rapid and very violent, for they are so minute that we cannot distinguish them by
sight, and so they would not have the force they have to act upon the other bodies if the rapidity of
their movement did not compensate for their lack of size.28
Flame, according to Descartes, is a body composed of very tiny, very rapidly moving parts. The size
and speed of its parts constitutes its power to burn.
In Principles IV, ss. 187, Descartes boasts that he has penetrated seeming mysteries such as
“the properties [proprietates] of magnets and of fire”, and “how a huge flame can be kindled from a
tiny spark in a moment” without appeal to the “occult qualities” of his predecessors:
In this book I have deduced the causes – which I believe to be quite evident – of these and many
other phenomena from principles which are known to all and admitted by all, namely the shape,
size, position and motion of particles of matter. And anyone who considers all this will readily be
convinced that there are no powers in stones and plants that are so mysterious, and no marvels
attributed to sympathetic and antipathetic influences that are so astonishing, that they cannot be
explained in this way. In short, there is nothing in the whole of nature (nothing, that is, which
should be referred to purely corporeal causes, i.e. those devoid of thought and mind) which is
27
28
CSM I 83/AT XI 7-8.
CSM I 83/AT XI 8.
13
incapable of being deductively explained on the basis of these selfsame principles; and hence it is
quite unnecessary to add any further principles to the list.29
Here Descartes replaces Aristotelian occult qualities with mechanistic properties. Occult qualities
were posited by Aristotelians to explain phenomena seemingly irreducible to mixtures of the four
elements (earth, air, fire, water). Famous examples: magnetism, effects of drugs, e.g., opium.
Descartes’ boast is perhaps not only about the fact that his explanatory principles known and
admitted by all but also that his most basic principles, unlike the Aristotelian elements, encompass
all natural phenomena caused by bodies, i.e., he doesn’t have to posit hidden powers in certain cases.
The merits of Descartes’ project of reforming the ground for corporeal causal powers by
replacing Aristotelian forms and qualities with the mechanistic properties is not addressed here.
Others have noted that Descartes’ own explanations are often flawed, unsatisfying. I aim only to
show that Descartes does not consider bodies devoid of forms to be bodies without activity, and
that his basic model for corporeal causal powers derives from a Scholastic view that bodies act
directly through their accidents. I also think that the model supports Descartes’ very frequent
claims that bodies are causes by identifying the ground of their activity. 30 But the occasionalist
29
CSM I 279/AT VIIIA 314-15.
Descartes very frequently refers to bodies as causes. See his discussion of change in Le Monde,
where he claims first that change in the created world happens in accordance with the laws of
nature, and then that “by ‘nature’ here I do not mean some goddess or any other sort of imaginary
power. Rather, I am using this word to signify matter itself, in so far as I am considering it taken
together with all the qualities I have attributed to it, and under the condition that God continues to
preserve it in the same way that he created it. For it follows of necessity, from the mere fact that he
continues thus to preserve it, that there must be many changes in its parts which cannot, it seems to
me, properly be attributed to the action of God (because that action never changes), and which
therefore I attribute to nature. The rules by which these changes take place I call the ‘laws of
nature’” (CSM I 92-3/AT XI 37). Here Descartes explains change in the world by pointing to matter
taken together with the qualities he has attributed to it, namely, “that its parts have had various
different motions from the moment they were created, and furthermore that they are all in contact
with each other on all sides without there beings any void between any two of them” (CSM I 923/AT XI 37). So Descartes thinks that change in the world depends on the motion of bodies,
coupled with the absence of empty space. It is important to notice that Descartes also claims that
30
14
interpretation of body-body causation in Descartes also finds support in his claim that the nature of
body is extension. If a body is simply an extended thing, then it has no features which could
constitute active powers.
This objection is the focus of the next Section.
3. The causal powers of res extensa
At Principles 1.53, Descartes claims that “each substance has one principal property which
constitutes its nature and essence, and to which all its other properties are referred”.31 The principal
attribute of corporeal substance is extension in length, breadth and depth and “[e]verything else
which can be attributed to body presupposes extension, and is merely a mode of an extended
thing”.32 And in Principles Part Two §23, Descartes claims that
[t]he matter existing in the entire universe is thus one and the same, and it is always recognized as
matter simply in virtue of its being extended. All the properties which we clearly perceive in it are
reducible to its divisibility and consequent mobility in respect of its parts, and its resulting capacity
to be affected in all the ways which we perceive as being derivable from the movement of parts.33
Descartes’ identification of extension as the principal attribute of body and his account of the
relationship between the principal attribute of a substance and its other properties are the bases of
an important objection to the claim that Cartesian bodies have causal powers. Hattab puts the
point this way:
[g]iven that all the properties of matter are derived from its divisibility and the consequent capacity
of its parts to be moved, Descartes leaves no room for active forces or causal powers originating
change must be attributed to matter in motion on the ground that the action of an unchanging God
can’t explain change.
Della Rocca argues that Descartes identifies bodies themselves as the particular causes of
motion in his discussion of the third law of motion in Principles, Part 2 at CSM I 240/AT VIIIA 61
(Della Rocca (1999), pp. 52-54). He notes, and I agree, that this passage provides important
evidence against the occasionalist interpretation of Descartes’ view of body-body causation, since
the passage is one in which Descartes is “giving us his official account of the causation of motion”,
rather than speaking loosely or casually about bodies as causes as even an occasionalist might do in
nontechnical passages (Della Rocca (1999), p. 52).
31
CSM I 210 / AT VIIIA 53.
32
CSM I 210 / AT VIIIA 53.
33
CSM I 232/AT VIIIA 52
15
from the nature of bodies. Properties such as active forces are not ultimately reducible to extension
so they do not belong to body.34
Notice that Hattab infers the claim that “Descartes leaves no room for active forces or causal
powers originating from the nature of bodies” from the claim that he holds that all the properties of
matter are reducible to its divisibility and consequent mobility. So she takes Descartes’ claim that all
the properties of matter are reducible to its divisibility and consequent mobility to mean that he
holds that all the properties of matter originate from the nature of body, i.e. extension. But the claim
that all the properties of matter originate from the nature of body conflicts with Descartes’ central
point in Principles Part Two §23.
Principles Part Two §23 begins with the claim that “[a]ll the variety in matter, all the diversity of its
forms, depends on motion”.35 Descartes’ aim in this section is to explain this point. He notes first that
“[t]he matter existing in the entire universe is thus one and the same, and it is always recognized as
matter simply in virtue of its being extended”.36 This claim follows from Descartes’ assertion that
variety in matter depends on motion: if variety in matter depends on motion, then matter considered
in itself is undifferentiated extension. His next claim explains the relationship between the nature of
matter and the properties which cause variety in matter: he says that “[a]ll the properties which we
clearly perceive in [matter] are reducible to its divisibility and consequent mobility in respect of its
parts, and its resulting capacity to be affected in all the ways which we perceive as being derivable
from the movement of parts”.37 This claim is primarily a descriptive one. But it has a proscriptive
overtone: we should ascribe to matter only those properties which we clearly perceive to be in
matter and those properties are reducible to its divisibility and consequent mobility. Since he claims
that “any variation in matter or diversity in its many forms depends on motion”, he must think that
34
Hattab (2000), p. 96.
CSM I 232/AT VIIIA 52
36
CSM I 232/AT VIIIA 52
37
CSM I 232/AT VIIIA 52-3
35
16
motion is something we clearly perceive to be in matter and so is something reducible to the
divisibility and consequent mobility of matter.38 But motion is not reducible to the divisibility and
consequent mobility of matter in the sense that it originates from the divisibility and consequent
mobility of matter.39 Given that Descartes claims in Principles Part Two §23 that all the properties
which we clearly perceive to be in matter are reducible to its divisibility and consequent mobility and
that motion is a property of matter, his claim that all the properties which we clearly perceive to be
in matter are reducible to its divisibility and consequent mobility cannot mean that all of these
properties originate from its divisibility and consequent mobility. By “reducible to” he means
something other than “originate from”.
What does “reducible to” mean, for Descartes in Principles Part Two §23?
1. The properties of matter are reducible to extension in the sense that the existence of these
properties does not require anything over and above, or other than, a finite parcel of
extension. So, e.g., spherical is reducible to extension in the sense that it is does not require
for its existence anything over and above, or other than, a finite parcel of extension.
38
CSM I 232-3/AT VIIIA 52-3
Descartes makes this point clear in his hypothetical account of creation in The World. There
Descartes first posits the creation of matter conceived as “a real, perfectly solid body which
uniformly fills the entire length, breadth and depth” of his imagined world and then suggests that
“this matter may be divided into as many parts having as many shapes as we can imagine, and that
each of its parts is capable of taking on as many motions as we can conceive” (CSM I 91/AT XI 334). Finally, he proposes that God really does divide matter into parts and suggests how he would do
so: [i]t is not that God separates these parts from one another so that there is some void between
them: rather, let us regard the differences he creates within this matter as consisting wholly in the
diversity of the motions he gives to its parts. From the first instant of their creation, he causes some
to start moving in one direction and others in another, some faster and other slower (or even, if you
wish, not at all); and he causes them to continue moving thereafter in accordance with the ordinary
laws of nature (CSM I 91/AT XI 34).
39
17
This view seems to accord with an analysis of modes as “ways of being extended”: Garber gives such
an analysis in Descartes’ Metaphysical Physics:
Descartes wants to make all of the properties of body geometrical. And so for him, modes, the term
he comes to choose in preference to accident, are to be the expression of the very essence or
attribute, in his terminology. For him, no accidents are to be merely tacked onto a substratum; for
him all accidents are to be either propria or accidentia propria, intimately linked to the essence of the
substance: as Descartes put it, all of the modes of body must be understood through its essence, its
principal attribute, extension (see Pr I 53). And thus, when he claims that the essence of body is
extension, he is not merely saying that all bodies have extension and necessarily so, as his scholastic
contemporaries might have meant such a claim; he is saying something stronger, that everything that
can really be attributed to body as such must be some way of another of being an extended thing.40
Objection to 1.:
“Spherical” and “moving” might both be ways of being an extended thing, but spherical does not
require for its existence anything over and above or other than a finite parcel of extension. But
motion does require for its existence something over and above or other than a finite parcel of
extension. So “ways of being extended” can’t mean reducible to extension where being “reducible
to extension” means not requiring for existence anything over and above or other than a finite
parcel of extension. And being “reducible to extension” does not mean requiring nothing for
existence over and above or other than a finite parcel of extension, since this view is incompatible
with the claim that motion is a mode of matter.
2. The claim that the properties of matter are “reducible to extension” in Principles 2.23 expresses the
same point made in Principles 1.53 where Descartes says that the properties of matter presuppose and
40
Garber, Descartes’ Metaphysical Physics, p. 69.
18
are referred to extension. Descartes there explains the point in epistemological terms: he says that
the properties of matter are “unintelligible except in an extended thing” (Principles 1.53).41
If 2. is correct then Descartes can attribute causal powers to bodies even if those powers don’t
originate from the nature of extension, or if they require something over and above, or other than, a
finite parcel of extension.
A fundamental corporeal causal power in Descartes’ natural philosophy is a moving body’s
power to move another body. (I say that this power is a fundamental one, since a great many other
causal powers will either be reducible to or depend on this one.) At Principles 2.43. Descartes
identifies one body’s power to move another with the former’s “power of continuing to move”. So
we must determine whether it makes sense to attribute to a body the power of continuing to move.
Descartes’ claim that the changes in motion which occur when a moving body collides with
another body are due to the moving body’s power of continuing to move gives rise to a different
objection to the view that Cartesian bodies can have genuine causal powers, which has to do with
the source of a body’s power of continuing to move. Hattab cites Descartes’ claim in the Second
Meditation that self-motion doesn’t belong to the nature of bodies as support for the general
41
Why the reduction language in Principles 2.23? N.B. the Latin verb is reducere, but see the French: Il
n'y a donc qu'une même matière en tout l'univers, et nous la connaissons par cela seul qu'elle est
étendue; parce que toutes les propriétés que nous apercevons distinctement en elle, se rapportent à
ce qu'elle peut être divisée et mue selon ses parties, et qu'elle peut recevoir toutes les diverses
dispositions que nous remarquons pouvoir arriver par le mouvement de ses parties. Perhaps the
reduction language echoes the methodological reduction advocated in Rules for the Direction of the
Mind, 5ff. Reduce involved questions to the simplest question whose answer is required by the more
involved questions. E.g., what properties can matter have? is reduced to the question what is
matter? The latter question is simple since there is no more basic question that can be asked. And
we can intuit the answer. Then we build our account of the properties of matter based on our
intuition of the nature of matter as extension.
19
conclusion that “[b]odies are inert on their own, requiring an external source of motion to begin to
move and continue to move”.42 In the Second Meditation, Descartes reports his conception of the
nature of bodies prior to engaging in methodological doubt. He says that he understood a body to
be something which “can be moved in various ways, not by itself but by whatever else comes into
contact with it. For, according to my judgement, the power of self-movement, like the power of
sensation or of thought, was quite foreign to the nature of body”.43 But he retracts this claim in the
Fifth Set of Replies:
You also question my statements that I had no doubts about what the nature of body consisted in,
and that I attributed to it no power of self-movement, and that I imagined the soul to be like a wind
or fire, and so on; but these were simply commonly held views which I was rehearsing so as to show
in the appropriate place that they were false.44
Furthermore, in his letter to Mersenne of October 28, 1640 he says that “[i]t is a big mistake to
accept the principle that no body moves of itself. For it is certain that a body, once it has begun to
move, has in itself for that reason alone the power to continue to move”.45
Notice that Descartes says in his letter to Mersenne that “a body, once it has begun to move,
has in itself for that reason alone the power to continue to move”.46 This suggests that he holds that
a body’s power to continue to move is constituted by its being in motion. Since being in motion is a
property that presupposes and is referred to extension, the property is compatible with Descartes’
account of the relationship between the nature of matter and its properties in Principles 1.53 and 2.23.
But why should we agree that bodies have in themselves the power to continue to move if they are
in motion? This claim finds support in Descartes first law of nature: “each thing, in so far as it is
simple and undivided, always remains in the same state, as far as it can, and never changes except as
42
Hattab (2000), p. 96.
CSM II 17/AT VII 26
44
CSM II 243/AT VII 351
45
CSM III 155/AT III 213
46
Ibid.
43
20
a result of external causes”.47 In other words, we know by the first law of nature that a body in
motion will remain in motion unless checked by something else. Since it is the case that a body in
motion will remain in motion unless checked by something else, we should agree that bodies have in
themselves the power to continue to move if they are in motion. The principle at work here seems
to be the following: (1) X has the power to continue to φ if (a) X is actually φing and (b) X will cease
to φ only if something else makes it cease.48 Note that Descartes does not need to establish that (a)
47
CSM I 241/AT VIIIA 63
We might think that if Descartes really does endorse this principle, then his claim that creatures
depend on God for their existence so long as they exist is in trouble. For the principle as applied to
existence yields the following claim: X has the power to continue to exist if (a) X is actually existing
and (b) X will cease to exist only if something else makes it cease. In the Fifth Set of Objections
Gassendi raises an objection along these lines against Descartes claim that creatures depend on God
for their existence (CSM II 210/AT VII 301-2). Descartes responds to Gassendi’s objection as
follows: “You say that we have a power which is sufficient to ensure that we shall continue to exist
unless some destructive cause intervenes. But here you do not realize that you are attributing to a
created thing the perfection of a creator, if the created thing is able to continue in existence
independently of anything else (CSM II 255/AT VII 371). What is interesting about this reply is
that Descartes does not attack Gassendi’s line of reasoning, i.e. he does not deny that it makes sense
to hold that an existing thing has the power to continue to exist if it will continue to exist in the
absence of a destructive cause. Rather, he points out that this view misattributes to a creature a
perfection that belongs to creators alone. What is the perfection that belongs to creators alone?
Descartes might mean that power to continue to exist independently belongs to a creator alone.
Why is this so? Descartes might mean that God, the sole creator, is the only being with the power to
continue to exist independently. If so, then his response begs the question?? I think that it is more
likely that the perfection that belongs to creators alone is the power to cause the existence of
something. Aquinas defends this view in Summa Theologiae 1.45.5. He says that “to produce being
absolutely, and not merely as this or that being, belongs to the nature of creation” (Aquinas.
“Summa Theologiae.” In Basic Writings of Saint Thomas Aquinas, vol. 1, ed. Pegis. Indianapolis:
Hackett, 1997, p. 440). Aquinas draws a distinction between producing being absolutely and
producing this or that being in order to distinguish the creative act, which is proper to God, from
the acts of creatures. Only God produces being absolutely, i.e. only God makes be something from
nothing. Creatures cause changes in things whose existence depends on God. This means that no
creature can keep itself in being, since to be able to keep something in being is to be able to produce
being absolutely. If this is Descartes’ point, then his response to Gassendi amounts to the following.
To cause existence is among the perfections of a creator; it is one of the features which distinguish
creators and creatures. To attribute to a creature the power to continue to exist is to attribute to that
creature the power to cause existence. This response indicates that he does not endorse without
qualification the principle that X has the power to continue to φ if (a) X is actually φing and (b) X
will cease to φ only if something else makes it cease. But this response also suggests that Descartes
does not object to the line of reasoning which grounds the principle itself, but rather to its
48
21
and (b) are necessary conditions for (1); his view makes sense so long as they are sufficient
conditions for (1). This principle seems to me to be unobjectionable. I clearly have the power to
continue to breathe if I am actually breathing and will only cease to breathe if something else makes
me cease.
Gary Hatfield denies that Cartesian bodies have in themselves the power to continue to
move. He thinks that God is directly responsible for this power. He reasons as follows. Since
Descartes appeals to the first law of nature to support his claim that bodies have in themselves the
power to continue to move and since the first law of nature is grounded in divine immutability, it
follows that a body’s power to continue to move is grounded in divine immutability. This means
that God is directly responsible for a body’s power to continue to move. Hatfield makes this point
in the following passage:
Descartes gives no reason why bodies should tend to persist in their own state other than the
immutable nature of the divine action that preserves bodies at each moment. A fortiori, in explaining
the tendency to persevere he does not appeal to the force that a body has by virtue of its motion.
Indeed, the relation is just the reverse: ‘the force of a body to act…is simply the tendency of
everything to persist in its present state’, a tendency that does not follow from any property of
matter, but rather from an attribute of God. Just as with the preservation of the quantity of motion,
it is difficult to see how a tendency to move could be grounded upon the immutability of God,
unless God were directly responsible for the tendency itself.49
Hatfield cites Descartes’ claim in Principles, Part Two §43 that a body’s power to act on
another body “consists simply in the fact that everything tends, so far as it can, to persist in the same
state, as laid down in our first law”.50 This claim follows from the claims that (1) a body’s power to
act on another body is constituted by its power to continue to move and (2) a body’s power to
continue to move is established by the first law of nature. Hatfield infers from Descartes’ appeal to
application to existence, which stands in need of a creative cause. The latter belief finds support in
the view that to cause the very existence of something is to create it from nothing. For this reason, I
don’t think that Descartes’ claim that bodies in motion have in themselves the power to continue to
move conflicts with his claim that creatures can’t keep themselves in existence.
49
Hatfield (1979), p. 126.
50
CSM I 243/AT VIIIA 66
22
the first law of nature in claim (2) that God is directly responsible for a body’s power to continue to
move. He justifies this inference on the ground that the first law of nature follows from divine
immutability. I think Hatfield is mistaken in thinking that a body’s power to continue to move
“does not follow from any property of matter”.51 I think that it is constituted by a property which
belongs to any body which has this power, namely, that body’s property of being in motion. And I
think that Descartes is entitled to attribute to a body in motion the power to continue to move on
the ground that X has the power to continue to φ if (a) X is actually φing and (b) X will cease to φ
only if something else makes it cease.
My position on this issue is prima facie similar to Michael Della Rocca’s. Della Rocca defends
Descartes’ claim that bodies have the power to continue to move and so to move other bodies on
the ground that Descartes holds that what a body tends to do is a function of its nature. If this is
the case, then a body’s tendency to remain in motion belongs to it by nature. Since Descartes thinks
that a body’s power to continue to move constitutes its power to move other bodies, the claim that a
body’s tendency to remain in motion belongs to it by nature entails that its force or power to move
other bodies belongs to it by nature. Della Rocca notes that
[i]n holding that a body’s nature is the source of what it can do causally, Descartes, as I have
interpreted him, is in agreement with the Aristotelian-scholastic tradition. On this tradition, a body’s
nature or form is the locus of causal explanations. Now…these forms or natures, as they were
traditionally conceived to be, were rejected by Descartes. But in rejecting this conception of the
natures of physical objects, he did not reject the general view that we should turn to the natures of
bodies in order to account for their causal powers.52
I think Della Rocca is right that Descartes’ rejection of substantial forms does not include a rejection
of the view that bodies have genuine causal powers. But I have shown that he thinks that it is
absurd even for proponents of substantial forms to hold them to be direct principles of action, and
51
52
Hatfield (1979), p. 126.
Della Rocca (1999), p. 67.
23
that he endorses the view of some Scholastics that substances act directly through their accidents
alone. So I don’t think that he considers the claim that bodies have causal powers to depend on the
claim that bodies have the tendency to remain in motion by nature. Rather I think that he considers
the claim that bodies have causal powers to depend on the claim that they have mechanistic
properties which constitute such powers. Chief amongst these is the power to continue to move,
which is constituted by a body’s property of being in motion, as discussed above. So my view does
not result in the problem which Della Rocca raises with respect to his own: “on the view I have
attributed to Descartes, the nature of a body consists in or at least somehow involves its tendency to
remain in its current state. It is not immediately clear how or if this view is compatible with his view
that extension constitutes the nature of a body”.53
Della Rocca, Michael. “If a Body Meet a Body.” New Essays on The Rationalists, eds. Gennaro and
Huenemann. Oxford: Oxford University Press, 1999, pp. 48-81.
Des Chene, Dennis. Physiologia: natural philosophy in late Aristotelian and Cartesian thought. Ithaca:
Cornell University Press, 1996.
Gabbey, Alan. “Force and Inertia in the Seventeenth Century: Descartes and Newton.”
Descartes: philosophy, mathematics and physics, ed. Gaukroger. Sussez: Harvester, 1980, pp. 230-320.
Garber, Daniel. Descartes’ Metaphysical Physics. Chicago: University of Chicago Press, 1992.
Garber, Daniel et al. “New Doctrines of Body and its Powers, Place and Space.” The Cambridge
history of seventeenth-century philosophy, eds. Garber and Ayers. Cambridge: Cambridge University Press,
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Hatfield, Gary C. “Force (God) in Descartes’ Physics.” Studies in the History and Philosophy of Science,
vol. 10, no. 2, 1979, pp. 113-140.
53
Della Rocca (1999), p. 69). Tad Schmaltz rejects Della Rocca’s account on this ground. See
Schmaltz (2003), p. 744.
24
Hattab, Helen. Descartes on Forms and Mechanisms. Cambridge: Cambridge University Press, 2009.
Hattab, Helen. “The Problem of Secondary Causation in Descartes: A Response to Des
Chene.” Perspectives on Science, vol. 8, no. 2, 2000, pp. 93-118.
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Natural Philosophy. Leiden: Brill, 2002.
Nadler, Steven. “Introduction.” Causation in early modern philosophy : Cartesianism, Occasionalism, and
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31-88.
Rozemond, Marleen. Suarez and the Unity of Consciousness (mss.)
Rozemond, Marleen. Descartes’s Dualism. Cambridge: Harvard University Press, 1998.
Schmaltz, Tad M. “Cartesian Causation: Body–Body Interaction, Motion, and Eternal
Truths.” Studies in History and Philosophy of Science, vol. 34A, no. 4, 2003, pp. 737-762.
Schmaltz, Tad M. Descartes on Causation. Oxford: Oxford University Press, 2008.
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