## 1. Ideas Understood as Modes of Thinking



According to Descartes' ontology there are *substances*,
*attributes*, and *modes*. These are understood relative
to one another, in terms of ontological dependence. Modes depend on
attributes, and attributes depend on substances. The dependence
relation is transitive; thus, modes depend ultimately on substances.
No substances, no modes. In *Principles*, Part I, Article 53,
Descartes says that a mode "presupposes" an attribute (AT
VIIIA 25; CSM I 210), and in Article 52 he says that an attribute
"presupposes" an existing substance. A *mode* of
some thing was understood by Descartes as a *a way of being*
that thing. So, where *X* is some substance, a mode *M*
is a way of being *X*. That said, in Article 52 he also says
that a substance minus its attributes cannot be known to the human
mind. Attributes are in fact what make existing substances
intelligible to the human mind. He reaffirms this in Article 62, where
he says that there is only a distinction in reason between an
attribute and an existing substance. (AT VIIIA 30; CSM I 214) This
strongly suggests that although one may draw a conceptual distinction
between an attribute and existing substance, the two are not distinct
in reality. They are really one and the same thing. (Nolan 1997,
Hoffman 2002) Subsequently, if mode *M* is a way of being
*X*, where *X* is the substance, the intelligibility of
*X* requires that we conceive some attribute *A*. And
so, strictly speaking, mode *M* is understood as a mode of
attribute *A*, where *A* is the attribute through which
the existing substance *X* is conceived (where in reality
*A* and *X* are presumably identical).



The nature of a mind, Descartes says, is to think. If a thing does not
think, it is not a mind. In terms of his ontology, the mind is an
existing (finite) substance, and thought or thinking is its attribute.
Insofar as the nature of a mind is to think, where thought is the
mind's defining feature, Descartes calls it the mind's
*principal attribute* (AT VIIIA 25; CSM I 210-11). An
*idea* is a mode of thinking. In being a mode of thinking, an
idea is understood as a way of being (an instance of) thinking, or an
idea is way in which an instance of thinking is manifested. This is
similar to what Descartes says about a body, its principal attribute,
and its modes. The nature of a body is to be extended (in length,
breadth, and depth). A body is a (finite) substance, and extension is
its attribute. Since extension is the defining feature of a body,
Descartes refers to it as a body's principal attribute. Shape is
a mode of extension. What this means is that shape is a way of being
extended, or a way in which an instance of extension is manifested.
Thus, shape is to extension as idea is to thought. Thus a shape
presupposes extension and an idea presupposes thinking, where each
principal attribute presupposes an existing substance.



Insofar as ideas are modes, they occupy the lowest rung on
Descartes' ontological ladder. This can be contrasted to
Plato's theory, for example, which casts ideas as substances,
occupying the upper-most rung of the ontological ladder. So, whereas
for Plato ideas are the most real things in the cosmos, for Descartes
ideas are among the least real. Another departure from Plato's
view was Descartes' taking ideas as the vehicles of
representation, as the items doing the representing. By contrast,
Plato took ideas to be the things represented. Socrates, for instance,
was taken by Plato to be a representation of the form or idea of man.
These differences are certainly enough to suggest that ideas are
playing significantly different roles in their respective systems. So,
it would not be reasonable to think that Descartes' view was
simply an extension of Plato's, despite the fact that Descartes
had adopted some of Plato's terminology.



Ideas are not the only modes of thinking. Doubting and judging, for
example, are also modes of thinking. Early in the Third Meditation,
Descartes works out a basic division of the various modes of thinking.
He sorts them into two kinds: simple and complex. Ideas are included
in the category of simple modes. Doubting, judging, and the like, are
included in the category of complex modes. Even so, all complex modes
include ideas as constituents. A complex mode of thought includes at
least two basic mental components: an idea and some
"additional" mental feature. He writes:



> 
> ...[C]onsiderations of order appear to dictate that I now
> classify my thoughts into definite kinds, and ask which of them can
> properly be said to be the bearers of truth and falsity. Some of my
> thoughts are as it were the images of things, and it is only in these
> cases that the term "idea" is strictly appropriate --
> for example, when I think of a man, or a chimera, or the sky, or an
> angel, or God. Other thoughts have various additional forms: thus when
> I will, or am afraid, or affirm, or deny, there is always a particular
> thing which I take as the object of my thought, but my thought
> includes something more than the likeness of that thing. Some thoughts
> in this category are called volitions or emotions, while others are
> called judgements. (AT VII 36-7; CSM II 25-6)
> 



In this passage, ideas are cast as modes of thinking that represent
(or present or exhibit) objects to the mind--objects such as a
man, or Pegasus, or the sky, or an angel, or God (and given what
Descartes says in the First Meditation, among the list of things
exhibited to the mind by way of its ideas, one could add colors,
sounds, feels, and so on (AT VII 20; CSM II 13-14)). On
Descartes' view, an idea is the *only* kind of (simple)
mode that does this. When considering one of the more complex modes of
thought--for instance, fearing a lion or affirming the
Pythagorean Theorem, where the lion and the theorem are the objects
presented--it is the idea that is doing the presenting; it is the
vehicle of representation. As Descartes will note in the Fourth
Meditation, he takes there to be two basic faculties (capacities or
abilities) of the mind: the *intellect* (or
*understanding*) and the *will*. Ideas are
"produced" by the intellect. So, the *idea* of the
Pythagorean Theorem has its origin in the faculty of the intellect or
understanding. The act of affirming, the other component of the more
complex thought of affirming this theorem, has its origin in the
faculty of the will. Contributions from both faculties, then, give
rise to the more complex kinds of thought.



Descartes is careful to not identify ideas as *pictures* or as
*visual images*, but instead says that they are *as it
were* [*tanquam*] images of things. This is a long-standing
theme, for we find it expressed as early as *The World* (AT XI
3-6; CSM I 81-2) and the *Optics* (AT VI
112-13; CSM I 165), and as late as the *Principles* (AT
VIIIA 32-3; CSM I 216-17) and *Description of the Human
Body* (AT XI 255-257; CSM I 322-23), where in these
contexts ideas are cast as representing their objects without
necessarily resembling them. This is important to the theory, since
the idea of cold or the idea of sweet, for example, insofar as they
are ideas, represent something to the mind, but they are not
*visual* images. The point holds for other ideas, such as the
idea of God, which Descartes explicitly lists in the above passage.
The idea of God represents something to the mind (it represents an
infinite substance), and in line with traditional theological
doctrine, supposing that God is non-spatial and non-temporal, the idea
cannot be understood as being a *visual* image of God.



Consistent with what he says in the above Third Meditation passage,
Descartes says in other places that an idea is "the form of any
given thought, immediate perception of which makes me aware of the
thought" (AT VII 160; CSM II 113). In his reply to Thomas Hobbes
(1588-1679), author of the Third Set of Objections, Descartes
says that an idea is "whatever is immediately perceived by the
mind" (AT VII 181; CSM II 127). In his reply to Pierre Gassendi
(1592-1655), author of the Fifth Set of Objections, he says that
the term "idea" is extended "to cover any object of
thought" (AT VII 366; CSM II 253). In a letter to Marin Mersenne
(1588-1648), dated July 1641, he says that "idea"
denotes "in general everything which is in our mind when we
conceive something, no matter how we conceive it" (AT III 393;
CSMK III 185). Long-standing interpretations take such passages as
telling us that ideas have the special feature of
intentionality--they are *directed at* their respective
objects. It is in terms of this directedness that the mind is said to
be *aware of* an object.



One long-standing interpretation, the *Representationalist*
interpretation, says that for Descartes the objects immediately
presented to the mind (by way of an idea) are *purely mental*
objects. This interpretation emphasizes Descartes' saying that
such objects are solely *in* the intellect, as when he says to
Caterus that the object of which the mind is immediately or directly
aware when having the idea of the Sun "...is not an actual
entity, that is, it is not a being located outside the
intellect..." (AT VII 103; CSM II 75) The object at which
the mind is directed, the *immediate* object of awareness, is
not the Sun itself, but is instead a purely mental object, which
represents (or stands for) the Sun in the heavens. This purely mental
object is said to constitute the *content* of the idea. On this
view, an idea is sometimes referred to as a *tertium quid*, a
third thing, which "stands between" the mind's eye,
so to speak, and the object that the idea represents.



Another long-standing interpretation, the *Direct Realist*
interpretation, says that for Descartes the objects immediately
represented or presented to the mind (by way of an idea) are not
always mental objects. (Nadler 1989) The idea of the Sun is understood
as being a mental operation (a mode of the mind) directed at the Sun
itself. In fact, on this interpretation, all ideas are, properly
speaking, to be understood as operations or acts of the mind. This
holds even for the idea of Pegasus. The idea is a mental operation and
in this case is directed at the mentally fabricated object, Pegasus.
Here, Pegasus is a purely mental object. By contrast, the (sensory)
idea of the Sun is directed at the Sun itself, the Sun in the heavens.
Thus, this interpretation allows ideas to be directed at mental and
extra-mental objects. The import of this interpretation is that the
*immediate* objects of awareness need not be purely
mental--so, no *tertium quid*--which differs
dramatically from the Representationalist interpretation. Although
both readings have their merits, the remainder of this entry will work
within the framework of the Representationalist reading.


## 2. Ideas and The Formal-Objective Reality Distinction



When speaking of an *existent* mode--in this case, an
actually occurring idea--Descartes will say that it possesses
*formal reality*. The formal reality of a thing is the kind of
reality the thing possesses in virtue of its being an *actual*
or an *existent* thing (AT VII 41-42, 102-4; CSM II
28-29, 74-5). For example, given that the Sun is an actual
or existent thing, it possesses formal reality. By contrast, given
that Pegasus is not an actual or existent thing, he does not possess
formal reality. Given that the *idea* of the Sun or the
*idea* of Pegasus are actual or existent ideas, where an idea
is actual or existent when it is being actively thought by a mind,
each would possess formal reality. 



Descartes took there to be three "levels" of formal
reality: the level of infinite substance, the level of finite
substance (as defined by its principal attribute), and the level of
mode. The level of formal reality of an infinite substance is greater
than that of a finite substance, and the level of formal reality of a
finite substance is greater than that of a mode. This is understood in
terms of ontological dependence. A mode depends for its formal reality
on the formal reality of a finite substance, and a finite substance
depends for its formal reality on the formal reality of an infinite
substance. An existent idea, in possessing the level of formal reality
of a mode, is less "real" than a finite substance, which
is in line with what was said in the previous section of this entry.




When speaking of ideas as representing things to the mind, Descartes
will refer to an idea's *objective reality*. The
objective reality of a thing is the kind of reality a thing possesses
in virtue of its being a *representation* of something
(*ibid*.). Given that the idea of the Sun and the idea of Pegasus
represent things to the mind (they represent or exhibit the Sun and
Pegasus respectively), each possesses objective reality. Descartes
says that ideas possess objective reality by their very nature.
Equally importantly, ideas are the only items in his ontology that
possess both formal and objective reality. (AT VII 42; CSM II 29)



As with formal reality, there are three "levels" of
objective reality. Descartes says, "Undoubtedly, the ideas which
represent substances to me amount to something more and, so to speak,
contain within themselves more objective reality than the ideas which
merely represent modes or accidents" (AT VII 40; CSM II 28).
And, Descartes' Third Meditation examination of his idea of God
reveals that the objective reality that it contains or possesses is
that associated with an infinite substance. At the very least, the
view is that the idea of God contains a level of objective reality
that is greater than that contained in an idea representing a finite
substance. Thus, the levels of objective reality possessed by ideas,
the reality they possess in virtue of their representing things to the
mind, are (nominally) three: infinite substance, finite substance, and
mode. The categories of the objective-reality hierarchy, then,
correspond to those of the formal-reality hierarchy. 



"The nature of an idea," Descartes says, "is such
that of itself it requires no formal reality except what it derives
from my thought, of which it is a mode" (AT VII 41; CSM II 28).
In fact, "In so far as the ideas are (considered) simply (as)
modes of thought, there is no recognizable inequality among them: they
all appear to come from within me in the same fashion" (AT VII
40; CSM II 27-8). Each idea is simply a mode of thought, and
insofar as an idea is an existent (or actual) mode, it possesses a
level of formal reality of that of a mode. He continues: "But in
so far as different ideas (are considered as images which) represent
different things, it is clear that they differ widely" (AT VII
40; CSM II 28). The differences will not only be in terms of the
"objects" represented, but, as noted above, ideas will
differ with respect to the levels of objective reality they contain
(AT VII 40; CSM II 28).



To see the formal-objective reality distinction at work within the
context of Descartes' theory, consider an idea that has been
mentioned several times already--the idea of God, as introduced
in the Third Meditation. Descartes' analysis of this idea begins
with his focusing on the fact that the idea represents to him an
infinite substance (AT VII 45; CSM II 31). The formal-objective
reality distinction suggests the following. When considered simply as
an existent mode of Descartes' mind, which is to consider it in
terms of its formal reality, Descartes sees no trouble in accounting
for the origin of the formal reality of this idea: the formal reality
possessed by this idea is derived from the formal reality of his mind.
In other words, the existence of the idea, as mode, depends on the
existence of his mind. But when considered in terms of what this idea
represents or presents to the mind, which is to consider the idea in
terms of its objective reality, Descartes discovers a problem, which
can be formulated: what is the origin of the idea's objective
reality? This challenge arises in light of Descartes'
saying:



> 
> Now it is manifest by the natural light that there must be at least as
> much (reality) in the efficient and total cause as in the effect of
> that cause. For where, I ask, could the effect get its reality from,
> if not from the cause? And how could the cause give it to the effect
> unless it possessed it? It follows from this both that something
> cannot arise from nothing, and also that what is more perfect --
> that is, contains in itself more reality -- cannot arise from
> what is less perfect. And this is transparently true not only in the
> case of effects which possess (what the philosophers call) actual or
> formal reality, but also in the case of ideas, where one is
> considering only (what they call) objective reality. A stone, for
> example, which previously did not exist, cannot begin to exist unless
> it is produced by something which contains, either formally or
> eminently everything to be found in the stone; similarly, heat cannot
> be produced in an object which was not previously hot, except by
> something of at least the same order (degree or kind) of perfection as
> heat, and so on. But it is also true that the *idea* of heat,
> or of a stone, cannot exist in me unless it is put there by some cause
> which contains at least as much reality as I conceive to be in the
> heat or in the stone. For although this cause does not transfer any of
> its actual or formal reality to my idea, it should not on that account
> be supposed that it must be less real. The nature of an idea is such
> that of itself it requires no formal reality except what it derives
> from my thought, of which it is a mode. But in order for a given idea
> to contain such and such objective reality, it must surely derive it
> from some cause which contains at least as much formal reality as
> there is objective reality in the idea. For if we suppose that an idea
> contains something which was not in its cause, it must have got this
> from nothing; yet the mode of being by which a thing exists
> objectively (or representatively) in the intellect by way of an idea,
> imperfect though it may be, is certainly not nothing, and so it cannot
> come from nothing. (AT VII 40-1; CSM II 28-9)
> 



The challenge in the examination of the idea of God is to account for
the origin of the idea's level of objective reality. He
determines that the formal reality possessed by his own mind cannot be
its origin. He concludes that there must be some being that in fact
possesses the requisite level of formal reality, which in this case
will be greater than that of a finite substance. (For more, see the
SEP entry on
 Descartes' epistemology.)
 Notice how this differs from what he says about the formal reality of
an idea, namely, that his mind is the cause or origin of an
idea's formal reality.



The examination of the idea of God follows almost directly upon the
introduction of the possible connection between the objective reality
of some of his ideas and the formal reality of extra-ideational or
extra-mental objects. Descartes' analysis of the idea of God
suggests a principle of representation, which is discussed in Section
4 of this entry.



There is a second distinction that Descartes introduces worth noting,
the *material-objective distinction*. Some scholars believe
that it is simply an alternate way of expressing the formal-objective
reality distinction. The material-objective distinction is never
clearly formulated in the body of the *Meditations*, though
Descartes employs it in his reply to Antione Arnauld
(1612-1694), in the Fourth Set of Replies.



Descartes introduces the material-objective distinction in the Preface
To the Reader of the *Meditations* (which was very likely
written after the *Meditations* and the Objections and
Replies). He says that the word "idea" is philosophically
ambiguous:



> 
> "Idea" can be taken materially, as an operation of the
> intellect, in which case it cannot be said to be more perfect than me.
> Alternatively, it can be taken objectively, as the thing represented
> by that operation; and this thing, even if it is not regarded as
> existing outside the intellect, can still, in virtue of its essence,
> be more perfect than myself. (AT VII 8; CSM II 7)
> 



The term "idea" can be used to refer to a specific kind of
act or operation of the mind--here, it is the act of
*representing*. In this sense, the idea is simply an existent
mode of the mind. In light of the formal-objective reality
distinction, since the formal reality of an idea (a mode) is derived
from the formal reality of the mind (its substance), it follows that
its level of formal reality cannot be greater than that of the mind.
This is what Descartes means when claiming that his ideas, understood
as operations of his mind, cannot be "more perfect" than
his mind. When using "idea" to refer to an operation of
the mind, "idea" is expressing what he calls the
*material* sense. Sometimes he will say, as he does in the
above quoted passage, that when understanding an idea to be an
operation of the mind that it is taken *materially*.



Alternatively, the term "idea" can be used to refer to
that which is presented or exhibited directly to the mind by way of
the mental operation. When using "idea" to refer the
*object* exhibited directly to the mind, "idea" is
expressing what he calls the *objective* sense. Sometimes he
will say, as he does in the above quoted passage, that when
understanding an idea as the object immediately presented to the mind
(by way of a mental operation), the idea is taken
*objectively*. 



Consider again the idea of God. When taking this idea materially, the
idea is understood as an operation of the mind. When taking this very
same idea objectively, the idea is understood as that which is
presented directly to the mind by way of this operation. The nature of
the object presented, Descartes says, can be more perfect than his
mind. So, even though he is not an infinite being, an idea can
nevertheless present to him a being that is infinite, a being that
possesses a greater level of reality than that possessed by a finite
substance. Again, the emphasis is that such is possible only if the
cause of the objective being possesses the requisite level of formal
reality, which in this case, as just noted, must be greater than that
of a finite substance.



Where the two distinctions may differ is with respect to how Descartes
employs them. When tracing out the origins of the formal and objective
reality possessed by an idea, Descartes employs the formal-objective
reality distinction. In some cases, as in the case of the idea of God,
the origin of the formal reality of the idea is his own mind, whereas
the origin of the objective reality is God (something that exists
independently of his mind). However, when Descartes is speaking about
the relation between an idea understood as a mental operation, and
this very same idea now understood as the object presented by way of
this operation, Descartes employs the material-objective distinction.
The difference is with respect to the number of relations in play in
the analysis. Consider again the idea of God. Concerning the
formal-objective reality distinction, the number of relations is two:
the relation between the idea as mode and the mind, and the relation
between the object presented in or by the idea and God. Concerning the
material-objective distinction, there is only one relation being
considered: the relation between the idea as mental operation and this
idea as object presented (via this operation).


## 3. Three Kinds of Idea



In the *Meditations*, after Descartes casts ideas as modes that
represent or exhibit objects to the mind, he divides ideas into kinds.
He says:



> 
> Among my ideas, some appear to be innate, some to be adventitious, and
> others to have been invented by me. My understanding of what a thing
> is, what truth is, and what thought is, seems to derive simply from my
> own nature. But my hearing a noise, as I do now, or seeing the sun, or
> feeling the fire, comes from things which are located outside me, or
> so I have hitherto judged. Lastly, sirens, hippogriffs and the like
> are my own invention. (AT VII 37-8; CSM II 26)
> 



Here, Descartes considers three kinds of idea: *innate ideas*,
*adventitious ideas*, and what are sometimes called
*factitious ideas*. The categories are determined by
considering the possible origins of the ideational contents presented
or exhibited to the mind. The first category includes ideas whose
contents have their origin in his nature (*qua* thinking
thing). An example is his idea of what thought or thinking is. The
third category includes ideas whose contents have their origin in the
contents of other ideas. An example would be the idea of Pegasus,
where its content is drawn perhaps from the contents of the idea of a
horse and the idea of a bird. Adventitious ideas, however, appear at
least at first glance to be importantly different, since Nature has
always taught him, he says, to think that they are "derived from
things existing outside me" (AT VII 38; CSM II 26). The category
arises in part from ordinary (pre-philosophical) experience:
"...I know by experience that these ideas do not depend on
my will, and hence that they do not depend simply on me. Frequently I
notice them even when I do not want to: now, for example, I feel the
heat whether I want to or not, and this is why I think that this
sensation or idea of heat comes to me from something other than
myself, namely the heat of the fire by which I am sitting" (AT
VII 38; CSM II 26). An account of their origin, he suggests, may
require an appeal to things that exist external to, or independently
of, his mind. Adventitious ideas include sensory ideas; ideas that
originate in sensory experience--such as the ideas of the Sun or
the Moon, but also the more simple ideas of colors, sounds, heat,
cold, and the like.



In Descartes' analysis of his idea of God, he discovers that it
is innate, since it is neither adventitious nor factitious. It is not
adventitious (or sensory), since he has had no sensory experiences of
God (i.e., he has never seen, heard, felt, smelt, or tasted God). This
would be in line with the theological demand that God is immaterial.
It is not factitious, for its content is something that his mind
cannot fabricate from other ideas--the idea represents an actual
infinity; at best his mind can only produce the factitious idea of a
potential infinity. (AT VII 46-7; CSM II 32) Even so, it becomes clear
to him that the innate idea of God is like the adventitious idea of
the Sun, but unlike the innate idea of what thought is (which has its
origin in his own nature), since like the adventitious idea of the
Sun, the objective reality possessed by the idea has its origin in the
formal reality belonging to something other than his own mind. His
analysis concludes that the origin of the objective reality must be in
an existing God (an actual infinite substance, something possessing an
infinite level of formal reality). In the Sixth Meditation, he will
ultimately conclude that the objective reality of his idea of body,
also innate, must have, like the innate idea of God, its origin in the
formal reality belonging to something other than his own mind, namely,
it will have its origin in an existing corporeal substance (an
extended being that possesses a finite level of formal reality).
Ultimately, the objective reality (i.e., contents) of his innate ideas
and adventitious ideas must have their origin in the formal reality of
things, some of the latter being things existing independently of his
mind.



This is not the only place in Descartes' work where innate and
adventitious ideas are cast as sharing the trait of having their
respective origins in things existing independently of his mind. For
instance, in *Comments on a Certain Broadsheet*, published in
1648, Descartes casts innateness as a *faculty* (AT VIIIB 358;
CSM I 304), which aligns with what he had said to Hobbes in the Third
Set of Replies: "...when we say that an idea is innate in
us, we do not mean that it is always there before us. This would mean
that no idea was innate. We simply mean that we have within ourselves
the faculty of summoning up the idea" (AT VII 189; CSM II 132).
Scholars note that this may be different from the way in which innate
ideas were cast in the Third Meditation. But in the sense of
*innate-as-faculty*, in *Comments on a Certain
Broadsheet*, Descartes goes on to say that there is a sense in
which even sensory ideas (ideas of qualities such as pains, colors,
sounds, and so on), ideas arising *via* the senses, which are a
species of adventitious idea, are nevertheless innate. The argument
unfolds as follows: Given that the human (or embodied) mind has the
faculty or capacity to have sensory ideas of pains, colors, sounds,
and so on, where these are occasioned on the occurrence or presence of
certain motions in the brain, and nothing of the motions in the brain
is transferred to the mind, and nothing resembling the pains, colors,
and sounds is present in bodies (including the brain), then the ideas
of pains, colors, and sounds (i.e., the ideas of those
*qualities*) "must be all the more innate." (AT
VIIIB 359; CSM I 304) 



One interpretation that has relatively recently emerged addresses the
concern over the alleged similarity between innate and adventitious
ideas by emphasizing the *role* that innate ideas play (Nolan
1997, Lennon 2007, Nelson 2008, De Rosa 2010). Consider, for example,
the adventitious or sensory idea of the Sun. This idea presents the
Sun to the mind as a shaped thing. An analysis of this idea reveals
that the innate idea of extension (body) is in play, for without it
the human mind simply could not experience (or even conceive) the Sun
*as* shaped. Shape presupposes extension. As Descartes puts it
in the *Principles*, everything "which can be attributed
to body presupposes extension, and is merely a mode of an extended
thing," which, according to Descartes, is aligned with the view
that "...shape is unintelligible except in an extended
thing..." (AT VIIIA 25; CSM I 210). In this sense, insofar
as a shaped thing is made intelligible to a human mind, the innate
idea of extension is involved. As some scholars have put it, the
innate idea underlies or informs the occurring idea of the Sun (Nolan
1997, Nelson 2008, De Rosa 2010). This interpretation finds further
support in what Descartes says in a letter to Princess Elisabeth,
dated 21 May 1643, where Descartes introduces what he calls the
"primitive notions." These are what in other contexts he
calls the innate ideas. In the letter, he claims that these ideas
serve as "...the patterns on the basis of which we form all
our other conceptions" (AT III 665; CSMK III 218). So, it is the
unique *role* of the innate ideas that distinguishes them from
adventitious ideas, where their role is to serve as that which makes
other things intelligible. 



Scholars agree that Descartes recognizes at least three innate ideas:
the idea of God, the idea of (finite) mind, and the idea of
(indefinite) body. In the letter to Elisabeth, he includes a fourth:
the idea of the union (of mind and body).



There is an alternate division of ideas worth noting. In the Third
Meditation, after having introduced the tripartite division of innate,
adventitious, and factitious ideas, Descartes continues to entertain
the possible origins of the contents of his ideas. His analysis turns
on the principle that an effect can never be greater than its cause,
which is underwritten by the self-evident principle that something
cannot come from nothing. He says: "And although one idea may
perhaps originate from another, there cannot be an infinite regress
here; eventually one must reach a primary idea, the cause of which
will be like an archetype which contains formally (and in fact) all
the reality (or perfection) which is present only objectively (or
representatively) in the idea." (AT VII 42; CSM II 29) Here,
Descartes introduces the notion of a *primary idea*. The import
of this notion is that the contents of some of his ideas may have
their origin in things located "outside" his
mind--that is, in things that exist independently of his mind.




Descartes' analysis suggests that the contents of some of his
innate ideas and all of his adventitious ideas have their origin in
things existing independently of his mind. Such ideas are included in
the category of Primary Idea. The innate idea of God is a primary
idea, since the objective reality it possesses has its origin the 
formal reality of God. Likewise, the innate idea of body is a primary
idea, since the objective reality it possesses has its origin in the
formal reality of body. And, as just noted, the adventitious idea of
the Sun is a primary idea, since the objective reality it possesses
has its origin the formal reality of the Sun. Factitious ideas,
whose contents have their origin in the contents of other ideas, no
doubt fall into the category of *Non-Primary idea*. A
non-primary idea is one whose objective reality has its origin in the
objective reality of some other idea. The factitious idea of Pegasus
is an example of a non-primary idea. 



This alternate scheme (Primary and Non-Primary), although partitioning
ideas differently than the initial scheme (Innate, Adventitious, and
Factitious), appears to do no philosophical harm to Descartes'
view. Even so, it is interesting the extent to which Descartes'
category of primary idea is later echoed in the views of John Locke
and David Hume, whose respective theories require a similar category,
which they refer to as *simple idea*. 


## 4. Primary Ideas and a Principle of Representation



Some scholars believe that in Descartes' brief discussion of
primary ideas there is suggested a principle of representation (Wilson
1978, Clatterbaugh 1980, Chappell 1986, Smith 2005a, 2010a). The
principle is notoriously difficult to formulate, and there is no
consensus among scholars as to how it is best understood. However, a
large number of scholars agree on one component of the principle,
which can be expressed as a necessary (though not a sufficient)
condition for representation. This principle of representation
(**PR**) can be expressed as follows:



> 
> **(PR)** Primary idea A represents object B only if the objective
> reality of idea A has its origin in the formal reality of object B.
> 



**PR** is at work in Descartes' analyses of all primary
ideas, which includes all innate and adventitious ideas. The innate
idea of his (i.e., Descartes') mind is said to be *of* or
to *represent* his mind insofar as the idea's objective
reality has its origin in the formal reality of his mind. The innate
idea of God is said to represent God insofar as the idea's
objective reality has its origin in the formal reality of God (an
infinite substance). The innate idea of a body is said to represent a
body insofar as the idea's objective reality has its origin in
the formal reality of a corporeal substance. The adventitious idea of
the Sun is said to represent the Sun insofar as the idea's
objective reality has its origin in the formal reality of the Sun. And
the list could go on. 



The following analogy may be instructive. Suppose that Socrates stands
before a mirror. Both Socrates and the mirror are actual things, so
both, using Descartes' terminology, would possess formal
reality. Each can presumably exist independently of the other. The
*image* of Socrates arises as a relation between Socrates and
the mirror. It cannot exist independently of Socrates or the mirror.
Destroy Socrates or the mirror, and this image of Socrates is
destroyed. Using Descartes' terminology, the *image* is
an objective being insofar as it is a *representation of*
Socrates. Although the image represents Socrates, it is nevertheless
"located" on the mirror's surface. And, since the
surface is a mode of the mirror, there is a sense in which this image
would be too. The mirror is the bearer of the image. This is a sense
in which the image "belongs to" the mirror. The
relationship to Socrates is different. The image is said to be an
image *of Socrates*. The image is *about* him. He is not
the bearer of the image, but is what this image *represents*.
So, the relation that Socrates has to this image must be importantly
different from the relation that the mirror has to this image.
Employing Descartes' terminology, and in light of **PR**, the
image is *of* Socrates insofar as this objective being (the
image) has its origin in the formal reality of Socrates. To be sure,
the image derives its existence, or its formal reality, from the
formal reality of the mirror, but its objective being has its origin
not in the mirror but in Socrates. 


## 5. The *Rules*: Simple Natures and the Concepts of Clarity and Distinctness



It is in the *Rules* that Descartes introduces the *simple
natures*. The simple natures are not only what our ideas are
*of*--that is, they not only constitute the contents of
our ideas, the "objects" immediately presented to the
mind--but are also the natures possessed by things. (AT X 399;
CSM I 32) Examples of simple natures are colors, sounds, smells,
shapes, sizes, extension, and the like. He says, for example, in Rule
Twelve, "if I judge that a certain shape is not moving, I shall
say that my thought is in some way composed of shape and rest; and
similarly in other cases." (AT X 420; CSM I 45) In the First
Meditation, Descartes mentions similar ideational elements "from
which all the images of things" are formed. (AT VII 20; CSM II
13-14) In the Second Meditation, in his analysis of the adventitious
idea of a piece of wax, Descartes again provides a list of such
ideational elements. (AT VII 30-32; CSM II 20-21) In the Third
Meditation, he refers to such items as "elements in my
ideas." (AT VII 44; CSM II 30) And, in the Sixth Meditation,
when revisiting some of what he had established in the Second
Meditation, talk of these qualities that are "the only immediate
objects of my sensory awareness" is again introduced. (AT VII
75ff; CSM II 52ff) So, although Descartes does not employ the
"simple natures" terminology in later work, the
philosophical notion certainly looks to be present in his later work.




Simple natures form an ordered, hierarchical system. Upon analysis
they appear to be sorted into two basic groups or classes, which not
surprisingly corresponds to Descartes' mind-body dualism. (AT X
399; CSM I 32) Descartes refers to this partition of simple natures as
the *enumeration*. The basic classes of this enumeration will
also be partitioned. In light of this, this ultimate
enumeration--the partition of the simple natures into the classes
of thinking and extended things--can be referred to as the
*master enumeration*. As laid out in the *Rules*, the
hierarchy is not understood in terms of the ontology, but in terms of
what must be known in terms of what. (AT X 381; CSM I 21) These groups
or classes are formed in light of epistemic priority. One group
includes those simple natures that presuppose the simple nature
*thought* or *thinking*, while the other group includes
those simple natures that presuppose the simple nature
*extension*. The view is that the simple nature *shape*,
for instance, presupposes the simple nature *extension* in that
the former is known (understood) on the basis of the latter. As
Descartes puts it later in the *Principles*, "shape is
unintelligible except in an extended thing." (AT VIIIA 25; CSM I
210) No extension, no shape. The same holds for the other class. The
simple nature *hot*, a sensible quality, presupposes the simple
nature *thought* or *thinking* in that the former is
known (or understood) on the basis of the latter. No thought or
thinking, no (feeling of) hotness. 



Descartes recognizes two forms of *conjunction* found among the
simple natures: necessary and contingent conjunction. (AT X 421f; CSM
I 45f) Two simple natures are said to be necessarily conjoined
whenever one presupposes (entails) the other. (*Ibid.*) So, for
instance, the simple nature *shape* is necessarily conjoined
with the simple nature *extension* insofar as the former
presupposes (or entails) the latter. An idea is said to be
*clear* whenever the necessary conjunction between simple
natures in the idea is exhibited or made explicit. Descartes'
procedure for making an idea "clearer" is to compare the
simple natures in the idea. He writes that the procedure: 



> 
> ...is carried over from one subject to another solely by means of
> comparison, which enables us to state that the thing we are seeking is
> in this or that respect similar to, or identical with, or equal to,
> some given thing. Accordingly, in all reasoning it is only by means of
> comparison that we attain an exact knowledge of the truth. (AT X 439;
> CSM I 57)
> 



He goes on to say that "Unity is the common nature which, we
said above, all things which we are comparing must participate in
equally." (AT X 449; CSM I 63 See also AT X 440f; CSM I 57f) The
simple natures *shape* and *size* share in common their
presupposing the simple nature *extension*. Extension is the
common nature; it unites such natures into a single *thing* (a
body). Thought or thinking is the common nature that unites the other
simple natures into a single *thing* (a mind). An idea is said
to be *obscure*, then, whenever no necessary conjunction (the
"presupposes" relation) is exhibited or made explicit in
an idea.



Ideas are said to be *confused* whenever they include or
contain simple natures belonging to the two mutually exclusive classes
of simple nature (the two classes together forming the enumeration).
Here, the Latin *confusio* means *mixed together*. The
adventitious idea of the Sun is an example of a confused idea. In
presenting the Sun as circular-shaped and hot, the idea includes
simple natures that belong to the two mutually exclusive classes.
*Shape* belongs to the class whose members presuppose the
simple nature *extension*, whereas *heat* (a quality)
belongs to the class whose members presupposes the simple nature
*thought* or *thinking*. An idea is said to be
*distinct*, then, whenever it includes or contains only simple
natures belonging to one of the mutually exclusive classes. The
astronomical idea of the Sun, as introduced in the Third Meditation,
looks to be an example of a distinct idea. It includes only those
simple natures belonging to the class whose members presuppose the
simple nature *extension*. (Smith 2010, 2015)



In the Third Meditation, Descartes introduces what scholars refer to
as "the truth rule": Whatever one perceives clearly and
distinctly is true. (AT VII 35; CSM II 24) In the Fifth Meditation, in
his analysis of the clear and distinct idea of a triangle, Descartes
argues that since "whatever is true is something (i.e.,
*real*)" (AT VII 65; CSM II 45), it follows that
"everything which I clearly and distinctly perceive to belong to
that thing (the triangle) really does belong to it..." (AT
VII 65; CSM II 45) As others have argued (Wahl 1995, Lennon 2007,
Smith 2010a, Smith 2015), for Descartes, to say that something was
"real" was in part to say that it existed independently of
a finite mind. This is the import of Descartes' proving the
existence of God and body. They are real things. In his analysis of
the idea of the triangle, Descartes concludes that the natures that he
clearly and distinctly perceives the triangle as possessing are in
fact *possessed by* the triangle. These natures are
*real*. 



Russell Wahl has argued that for Descartes *truth* was related
directly to *natures*. (Wahl 1995) What is true, he says,
"is the object before the mind and not the idea--not the
operation of the mind, but what is perceived." (Wahl 1995, p.
188) In other words, truth is not related to the idea taken
materially, but to the idea taken objectively. This, he says, is no
doubt related to Descartes' claim that whatever is true is
something (real). (AT VII 65; CSM II 45) The import of this view is
that the simple natures, which constitute the contents of ideas, are
also the very same natures possessed by things--at least when the
idea is clear and distinct. Here, the simple natures look to be
serving as an ontological bridge, so to speak, between the mind and
extra-mental reality. Wahl's reading is controversial, but worth
noting, since the potentiality lurks in its being able to bring closer
together the Representationalist and Direct Realist readings.



A relatively recent suggestion, which emerged in part as a response to
the conflict between the Representationalist and Direct Realist
interpretations, comes from Paul Hoffman. (Hoffman 2002) He bases his
suggestion on a view held by Aquinas. Given that simple natures are
the ontological elements of ideas and things, Hoffman in essence
argues that it is the simple natures themselves that possess the two
kinds of reality that Descartes had introduced in the Third
Meditation, namely, formal and objective reality. (Hoffman 2002)
Consider the adventitious idea of the Sun. As noted earlier, this idea
is obscure and confused. Even so, it reportedly represents the Sun in
the heavens. Descartes makes clear in the Third Meditation that the
astronomical idea of the Sun better "resembles" the object
reportedly in the heavens than does the adventitious idea. One way
this may be the case is that the astronomical idea is clear and
distinct in that it includes only those simple natures that presuppose
*extension*, such as *shape*, *size*,
*motion*, and so on (distinct), and it exhibits the
presupposition relation (clear). The Sun is a body whose nature is
extension (in length, breadth, and depth). 



"The sun as it exists objectively," says Hoffman,
"is able to represent the sun as it exists formally in the
heavens precisely because it is the same thing that has these two
modes of existence." (Hoffman 2002, p. 168) That is, the Sun
possesses both formal and objective reality, or rather, the simple
natures that constitute the thing referred by the words "the
Sun" possess both formal and objective reality. Hoffman's
suggestion is that it is the *objective reality* possessed by
the simple natures that the mind "engages" when perceiving
the Sun. It is via the Sun's objective being that the mind has
"access to" the Sun in the heavens. This suggestion would
seem to straddle both the Representationalist and Direct Realist
interpretations, though, as Hoffman himself characterizes his view,
his suggestion leans in the direction of the Direct Realist
interpretation. 



That said, there is trouble lurking in Hoffman's suggestion.
Descartes very clearly says that *ideas* are the items in his
ontology that possess objective reality, and they possess it by their
very nature. (AT VII 42; CSM II 29) If the Sun, for instance, or any
of the simple natures that constitute the Sun, are the items that
possess objective reality, then the Sun or the simple natures that
constitute it are *ideas*. But the Sun, or the simple natures
that constitute it, also presumably possess formal reality, which is
the kind of reality a thing possesses insofar as it is a real or
actual thing. If by "real" Descartes in part means
*exists independently of a finite mind*, as Wahl and Lennon
contend, then the Sun, or the simple natures that constitute it,
insofar as they possess formal reality, exist independently of the
finite mind. This would entail that ideas can and do exist
independently of the finite mind. But this runs counter to
Descartes' ontology. For further examination of the
Representationalist and Direct Realist interpretations, which includes
a critical look at Hoffman's suggestion, see (Smith 2010a).