## 1. The Modal Characterization of the Essential/Accidental Property Distinction



According to the *basic modal characterization* of the
distinction between essential and accidental properties, which is the
characterization given at the outset,



\(P\) is an *essential property* of an object \(o\)
just in case it is necessary that \(o\) has \(P\), whereas
\(P\) is an *accidental property* of an object \(o\)
just in case \(o\) has \(P\) but it is possible that
\(o\) lacks \(P\).




Putting this into the language of *possible worlds* that
philosophers often adopt,



\(P\) is an *essential property* of an object \(o\)
just in case \(o\) has \(P\) in all possible worlds, whereas
\(P\) is an accidental property of an object \(o\) just in
case \(o\) has \(P\) but there is a possible world in which
\(o\) lacks \(P\).




Although the basic idea behind the modal characterization is clear
enough from these statements, a moment's reflection reveals a
little bit of trouble. Many properties (some philosophers would say
*all* properties) are such that in order for an object to
possess them, that object must exist. According to the basic modal
characterization, any such property, if possessed by a contingently
existing object, will be counted as an *accidental* property of
that object. But this seems wrong. Consider the property of being a
dog. It is plausible (and for present purposes we assume it is true)
that an object must exist in order to possess this property. Now
consider a particular dog named 'Emma', who in fact exists
but who might not have existed. There is a possible world in which
Emma does not exist. And in this world (given our assumption) Emma is
not a dog, since Emma does not exist there. So, according to the basic
modal characterization, being a dog is an *accidental* property
of Emma. But however we characterize the distinction between essential
and accidental properties, the characterization should not by itself
rule out the intuitively compelling claim that Emma is
*essentially* a dog. So the basic modal characterization seems
flawed.



In response to this point, it is tempting to turn to a variant of the
basic modal characterization, *the existence-conditioned modal
characterization*, according to which



\(P\) is an *essential property* of an object \(o\)
just in case \(o\) has \(P\) and it is necessary that \(o\) has \(P\) if
\(o\) exists, whereas \(P\) is an *accidental
property* of an object \(o\) just in case \(o\) has
\(P\) but it is possible that \(o\) lacks \(P\) and yet
exists.




But this formulation too is less than satisfactory. A widely noted
problem for this way of drawing the distinction is that it makes
existence into an essential property of each object, since no object
could lack existence and yet exist. Thus, this characterization of the
essential/accidental property distinction effectively rules out a
theist's claim that only God has existence as an essential
property. But a good characterization of the distinction should not
rule on a substantive matter in this way.



Arguably neither of these problems is devastating. Those who favor the
basic characterization can say that typically when someone claims, for
example, that Emma is essentially a dog, what is really meant is not
that Emma has essentially the property of *being a dog*, but
instead that Emma has essentially the property of *being a dog if
existent*. Existence will be treated specially on this approach:
the claim that an object has existence as an essential property will
not be taken as the claim that the object has as an essential property
the property of *being existent if existent*; instead the claim
will be taken at face value. Those who favor the existence-conditioned
characterization can say that when someone says that only God has
existence as an essential property, what is really meant is that only
God has existence as a *necessary* property, where a necessary
property of an object is a property that the object possesses in all
possible worlds. (According to the basic modal characterization, an
essential property is the same as a necessary property.) Both
approaches may be faulted for making a special case of the property of
existence. But that is not perhaps such a great fault, given that
existence does seem to be a special case and that it is treated
specially in other areas of philosophy as well. (It is perhaps worth
pointing out that according to many philosophers--Kant, Russell,
and Frege to name three--existence is not a property at all. If
this is right, then existence is indeed a very special case.) In what
follows, we shall not be concerned with the details arising from the
need for some sort of existence condition--either in the
statement of the definition of an essential property (as on the
existence-conditioned modal characterization) or in the properties
that are taken to be essential (as on the basic modal
characterization). There are other ways of explaining the distinction
between essential and accidental properties of objects in modal terms
(to be discussed in SS2), but what we have called the *basic
modal characterization* and the *existence-conditioned modal
characterization* are the standard ways. Together, usually
indiscriminately, these amount to what we call the *modal
characterization*.



The central notion involved in any modal characterization of the
distinction between essential and accidental properties is that of
*metaphysical necessity/possibility*. But, since there are a
number of notions that correspond to the many ways that we use the
words 'necessity' and 'possibility', it is
helpful to contrast the relevant notion of necessity/possibility with
some other notions with which it might be confused.



If one claims that something is possible, it is sometimes natural to
take this to mean that one does not know it to be false. For example,
suppose that you ask someone whether Socrates ever went to Sparta and
she answers that it is possible. It is natural to understand her as
saying that she does not know that Socrates did not go to Sparta.
Thus, the possibility that is expressed here is a kind of
*epistemic* possibility (in particular, one according to which
\(p\) is epistemically possible for an agent \(X\) just in
case not-\(p\) is not known by \(X)\). This notion of
epistemic possibility is clearly distinct from the notion of
metaphysical possibility, since there are cases of epistemic
possibilities that are not metaphysical possibilities. Of
Goldbach's Conjecture (that every even number greater than two
is the sum of two primes) and its denial, each is epistemically
possible but one (we know not which) is not metaphysically possible.
And there are cases of metaphysical possibilities that are not
epistemic possibilities. That there are only two planets in our solar
system is metaphysically possible but not epistemically possible for
most of us, given that most of us know that there are not only two
planets in our solar system. (This is not to deny that there may be
some notions of epistemic possibility--for example, maximally
complete ways the universe can coherently *be conceived* to
be--for which it is at least plausible to suppose that every
metaphysical possibility is also an epistemic possibility. Even if
this is so, the notions of metaphysical possibility and epistemic
possibility are distinct.)



In addition to various notions of epistemic possibility, philosophers
have been concerned with three particular notions of possibility that
are generally regarded as non-epistemic: *logical possibility*,
*metaphysical possibility*, and *physical possibility*.
On one common view, the physical possibilities are a subset of the
metaphysical possibilities, which in turn are a subset of the logical
possibilities. (But see Fine (2002) for an opposing view.) Here are a
couple of examples of things that are logically possible but neither
metaphysically nor physically possible: the Eiffel Tower's being
red all over and green all over at the same time; the Eiffel
Tower's being red but not
 extended.[1]
 Here is an example of something that is logically and metaphysically
possible but not physically possible: the Eiffel Tower's
traveling faster than the speed of light. The Eiffel Tower's
being both red and not red at the same time is possible in none of the
senses while its traveling faster than a speeding bullet is possible
in all of them.



To supplement these examples, it would be nice to give
characterizations of the three notions that are free from controversy.
That is easier said than done. Nonetheless, we offer some
characterizations that are relatively uncontroversial. Metaphysical
possibility is often taken as a primitive notion that figures into the
idea of a physical possibility: a proposition is physically possible
if and only if it is metaphysically compossible with the laws of
physics. (Other nomological possibilities, such as chemical or
biological possibility, can be understood similarly.) Assuming that
the notion of a
 logical truth
 is understood, then the logical necessities are simply the logical
truths, so that the logical possibilities are those things whose
negations are not logical truths.



We end this overview of the modal characterization of the
essential/accidental property distinction by mentioning a notion that
is close to, but different from, that of an essential property. It is
easy to confuse the notion of an essential property--a property
that a thing could not *lack*--with the notion of a
property that a thing could not *lose*, so it is worth taking a
minute to reflect on the difference. Of course, any property that a
person could not lack is one that that person could not lose, since by
losing a property the person comes to lack it. Still, the
"reverse" does not hold. There are properties that a
person could not lose--like the property of having spent
Christmas 2007 in Tennessee--that are nevertheless not essential
to that person.


## 2. Other Ways of Characterizing the Essential/Accidental Property Distinction



The modal characterization of an essential property of an object as a
property that an object *must* possess fits well with (at least
one aspect of) our everyday understanding of the notion of
essentiality, which often seems simply to be the notion of necessity.
To say that something is essential for something else is typically
just to say that the first is necessary for the second. But however
well this account fits with (this aspect of) our everyday
understanding of essentiality, it has some consequences that may be
surprising: this characterization classifies the property of being
such that there are infinitely many primes (or, perhaps, being such
that there are infinitely many primes if the thing in question is
existent) as essential to Socrates (as well as to all other things),
since Socrates (like all other things) must have this property.
Socrates must have this property for the simple reason that it is
necessary that there are infinitely many primes. Moreover, this
characterization classifies the property of being the sole member of
the unit set \(\{2\}\) as essential to the number 2, given that it is
necessary that 2 is the sole member of the unit set \(\{2\}\).



Some philosophers, most prominently Kit Fine (1994), have found these
results disturbing. Fine thinks that the notion of an essential
property of a thing should be bound up with the notion of the thing's *nature* or *what it
is to be that thing*, but, Fine thinks, being such that there are
infinitely many primes intuitively has nothing to do with *what it
is to be* Socrates. And although it seems that having the number 2
as its sole member is part of what it is to be the unit set \(\{2\}\), it
does not seem that being this unit set's sole member is part of
what it is to be the number 2. It is Fine's view that these
sorts of properties are *counterexamples* to the modal
 characterization.[2][3]
 To replace the modal characterization, Fine offers a *definitional
characterization* of essential properties, according to which the
essential properties of an object are those of its properties that are
part of the object's "definition". What exactly is a
"definition" of an object? This is a difficult question.
At first sight, it seems to be a category mistake: it is words and
perhaps concepts--but not objects--that have definitions.
Even so, it must be admitted that some objects--such as the
number 2 and the unit set \(\{2\}\)--do seem to be definable: it is
plausible to think that the number 2 is defined as being the successor
of the number 1; and it is plausible to think that the unit set \(\{2\}\) is
defined as being the set whose sole member is the number 2. But other
objects--such as Socrates--do not seem to admit so readily
of definition. So even if the notion is understood well enough for
some objects (never mind that not everyone would allow that the number
2, for example, is an object), a major challenge for the advocate of
the definitional characterization is to provide a respectable general
understanding of the notion of a definition for an object.



Another issue bears mentioning inasmuch as the present article
concerns the *distinction between essential and accidental
properties* and not merely different ways that one may
characterize what an essential property is. There is a recognized
analytic connection between the terms 'essential property'
and 'accidental property' such that the properties of a
given thing divide exclusively and exhaustively into the categories
*essential* and *accidental*. Although the thought that
a thing's essential properties are those that are a part of its
definition has caught on in the philosophical literature, the thought
that a thing's accidental properties are those of its properties
that are not part of its definition has not. For example, few would
say that it is merely accidental to Socrates to be the sole member of
\(\{\text{Socrates}\}\). In short, the phrase 'accidental
property' tends to be used in the sense of a modally accidental
property.



Several philosophers have defended non-standard versions of the modal
characterization in light of Fine's putative counterexamples.
Edward Zalta (2006) was among the first. He distinguishes between
abstract objects (such as numbers and fictional characters) and
ordinary objects (such as Socrates). According to Zalta, every object
necessarily exists (whether abstract or ordinary), but ordinary
objects are not necessarily concrete. Indeed, an ordinary object such
as Socrates is concrete in some possible worlds but non-concrete in
others. Zalta suggests two separate accounts of essence, one
corresponding to abstract objects and the other corresponding to
ordinary objects. Here is Zalta's account of essence for
ordinary objects, slightly simplified:



\(P\) is an *essential property* of an ordinary object
\(o\) just in case (1) it is necessary that \(o\) has
\(P\) if \(o\) is concrete, and (2) it is not necessary that
\(o\) has \(P\).




In all possible worlds, Socrates is such that there are infinitely
many primes (whether Socrates is concrete or non-concrete). Thus,
condition (2) is not satisfied. Thus, this is not one of
Socrates's essential properties. (In Zalta's terminology,
this is not one of Socrates's *strongly* essential
properties, although Zalta would say that it is one of
Socrates's *weakly* essential properties, since condition
(1) is satisfied.) Here is Zalta's account of essence for
abstract objects:



\(P\) is an *essential property* of an abstract object
\(o\) just in case it is necessary that \(o\) *encodes* \(P\).




Only abstract objects are capable of *encoding* properties,
according to Zalta. To say that an abstract object encodes a property
is to say that the property is included in our conception of the
object. Thus, the fictional character Sherlock Holmes encodes the
property of being a detective, even though Sherlock Holmes does not
have this property. (In Zalta's terminology, Sherlock Holmes
does not *exemplify* this property. Sherlock Holmes exemplifies
properties such as being created by Arthur Conan Doyle and having been
portrayed by Jeremy Brett.) According to Zalta, being a detective is
one of Sherlock Holmes's essential properties. In contrast,
being such that there are infinitely many primes is not one of
Sherlock Holmes's essential properties, since this property is not
included in our conception of Sherlock Holmes.



The asymmetry between the essential properties of Socrates, who is an
ordinary object, and {Socrates}, which is an abstract object, is
explained: given the theory and definitions proposed, it is not
essential to Socrates that he is an element of {Socrates}, but it is
essential to {Socrates} that Socrates is an element of it (see Zalta
2006, SS5, for the details).



Fabrice Correia (2007) suggests a different version of the modal
characterization, based on a non-standard conception of modality:



\(P\) is an *essential property* of an object \(o\)
just in case it is *locally necessary* that \(o\) has
\(P\) if there are facts about \(o\).




In order to understand this characterization, we must first understand
Correia's non-standard conception of modality, inspired by
Arthur Prior (1957). Philosophers typically regard possible worlds as
giving a complete description of a possible state of the universe.
These are what Correia calls *globally* possible worlds.
*Locally* possible worlds form a broader class. They include
*all* the globally possible worlds, but also *strictly
locally* possible worlds, which are incomplete and do not include
facts about certain objects. A strictly locally possible world is
"a globally possible world in miniature" (2007, pp.
72-73). Correia suggests that there are strictly locally possible
worlds in which there are facts about Socrates but no facts about
prime numbers. Thus, it is not *locally necessary* that
Socrates has the property of being such that there are infinitely many
primes. Thus, this is not one of Socrates's essential
properties.



In a series of papers, Berit Brogaard and Joe Salerno (2007a, 2007b,
2013) have defended a version of the modal characterization that
relies on their non-standard conception of counterfactuals:



\(P\) is an *essential property* of an object \(o\)
just in case (1) it is necessary that \(o\) has \(P\) if
\(o\) exists, and (2) if nothing had \(P\), then \(o\)
would not exist.




In order to understand this characterization, we must first understand
Brogaard and Salerno's non-standard conception of
counterfactuals. According to Brogaard and Salerno, counterfactuals
with impossible antecedents ("counterpossibles") can be
false (rather than being "vacuously true," as standard
accounts would have it). For example, Brogaard and Salerno would say
that the following counterfactual is false: If nothing had the
property of being such that there are infinitely many primes, then
Socrates would not exist. Since this counterfactual is false,
condition (2) is not satisfied. Thus, Socrates is not essentially such
that there are infinitely many primes.



Another account, defended by Nathan Wildman (2013) and suggested by Sam Cowling (2013), appeals to David Lewis's (1983, 1986) distinction between *sparse*
properties and *abundant* properties:



\(P\) is an *essential property* of an object \(o\)
just in case (1) it is necessary that \(o\) has \(P\) if
\(o\) exists, and (2) \(P\) is a sparse property.




As Wildman and Cowling point out, there are several ways of cashing
out the distinction between sparse properties and abundant properties
(see Schaffer (2004) for a thorough discussion). The basic idea is
that sparse properties are somehow more fundamental than abundant
properties (they somehow "carve nature at the joints").
What is important is that on any plausible account of the distinction,
the properties invoked by Fine will not count as sparse properties.
Thus, condition (2) will not be satisfied.



David Denby (2014) defends a similar version of the modal
characterization, appealing to the more familiar distinction between
*intrinsic* properties and *extrinsic* properties:



\(P\) is an *essential property* of an object \(o\)
just in case (1) it is necessary that \(o\) has \(P\) if
\(o\) exists, and (2) \(P\) is an intrinsic property.




Roughly, an intrinsic property is a property that an object possesses
*in isolation*, while an extrinsic property is a property that
an object possesses *only in relation to other objects*. Again
there are different ways of cashing out this distinction. But again
the important point is that on any plausible account of the
distinction, the properties invoked by Fine will not count as
intrinsic properties. Thus, condition (2) will not be
 satisfied.[4]




In connection with the definitional characterization, it should be mentioned that Fine (1994) also argues that modal truths are reducible to truths about essence. Metaphysically necessary truths, for example, are identified with those propositions which are true by virtue of the essence of all objects whatsoever. This reductionist idea has generated a significant amount of literature in recent years. Among others, see Jessica Leech (2018), Carlos Romero (2019), Robert Michels (2019), and Nathan Wildman (forthcoming). 


In addition to the modal characterization and the definitional
characterization, there is yet another way of characterizing the
notion of an essential property. It agrees with the definitional
characterization that the modal characterization is too liberal in
what it counts as essential, but it avoids appeal to the notion of a
definition of an object. On the *explanatory characterization*,
the essential properties of an object are the object's deepest
explanatory properties--those properties that figure
fundamentally into explanations of the object's possessing the
other properties it does. (For example, having six protons might count
as an essential property of a carbon atom because this property
figures fundamentally into explanations of its possession of other
properties, like its bonding characteristics.) This sort of account
threatens to make the essential/accidental property distinction
relative, since what counts as explanatorily primary seems to depend
on the interests and abilities of the explainers. Some advocates of the explanatory characterization, such as Meghan Sullivan (2017), are willing to accept that the distinction is relative in some sense. Others, such as
Irving Copi (1954) and Michael Gorman (2005), hold that there is a
more "metaphysical" and less "epistemic"
understanding of the notion of explanation, according to which one
thing explains another thing just in case there is a certain
mind-independent relation that holds between them. Just as the
advocate of the definitional characterization is challenged to provide
a respectable understanding of the relevant notion of definition, the
advocate of the explanatory characterization is challenged to provide
(or to borrow from the philosophy of science) a respectable
understanding of the relevant notion of explanation.



The distinction between accidental and essential properties is, at
least on the most basic version of each account, both exclusive and
exhaustive. (On some more refined versions of these accounts, the
distinction remains exclusive, but not exhaustive. Exhaustiveness is
lost when certain properties--like the property of being such
that there are infinitely many primes--are not counted as
properties to which the essential/accidental distinction applies. See
the discussion of Della Rocca (1996a) in SS3.) In addition, it
seems that the root of each of the characterizations goes back at
least to the work of Aristotle. (For the modal characterization, see
*Topics* 102b5ff; for the definitional, see
*Metaphysics* 1031a12; and for the explanatory, see
*Posterior Analytics* 74b5ff. For more on the notion of essence
in Aristotle's work, see the entry on
 Aristotle's Metaphysics.)
 It is not clear whether these three characterizations should properly
be thought of as competing characterizations of a single notion or
instead as ways of trying to capture three related, but different, and
equally legitimate, notions. (A similar point has been made by Livingstone-Banks (2017) and Cowling(2013).) Since the modal characterization has been so common, and since *the distinction between essential and accidental properties*, which is the topic of this entry, is almost always understood modally, it will dominate the remainder of this entry.


## 3. Four Ways of Characterizing Essentialism



There are at least four fairly standard ways of characterizing
essentialism, and by considering two extreme views, we can easily see
the differences among these four characterizations. According to the
first extreme view--one that it is natural to call *maximal
essentialism*



all of any given object's properties are essential to it.




According to the other extreme view--one that it is natural to call
*minimal essentialism*



there are virtually no limits to the ways in which any given object
might have been different from the way that it actually is, so that
the only essential properties of an object are what we might think of
as its trivial essential properties--properties like being either
\(F\) or non-\(F\) (for any property \(F\)) and being
self-identical.




Should so-called minimal essentialism really count as a form of
essentialism? And should so-called maximal essentialism really count
as a form of essentialism? There are four positions in logical space
with respect to these questions: yes and yes; yes and no; no and yes;
and no and no. Each of these positions is occupied by some reasonably
prominent characterization of
 essentialism.[5]



The first position--according to which both "minimal
essentialism" and "maximal essentialism" count as
genuine forms of essentialism--is occupied by the
characterization of essentialism that was offered at the outset:



the doctrine that (at least some) objects have (at least some)
essential properties.




We are inclined to think that this simple and straightforward
characterization is the most common understanding of essentialism,
although it is rarely explicitly stated. (Mackie (2006, p. 1) provides
an example of someone who does explicitly use this
characterization.)



The second position--according to which "minimal
essentialism" but not "maximal essentialism" counts
as a genuine form of essentialism--is occupied by the
characterization that Quine (1953b/1976, pp. 175-6) very
famously offered:



> 
> the doctrine that some of the attributes of a thing (quite
> independently of the language in which the thing is referred to, if at
> all) may be essential to the thing, and others accidental.
> 



In more formal terms, essentialism, Quine (1953b/1976, p. 176) says,
is the doctrine that there are true sentences of this form:
\(\exists x(\Box Fx \amp Gx \amp{\sim}\Box Gx)\) (where
'\(\Box\)' may be read as 'it is necessary
that'). According to "maximal essentialism" any
given object has only essential properties. It has no accidental ones.
That means that according to "maximal essentialism", there
will be no properties to "go in for" the
'\(G\)' in Quine's sentence schema; and so,
"maximal essentialism" is no form of essentialism at all
on Quine's characterization.



The third position--according to which "maximal
essentialism" but not "minimal essentialism" counts
as a form of essentialism--is occupied by the characterization of
essentialism as



the view that (at least some) objects have (at least some) non-trivial
necessary properties.




Della Rocca (1996a) thinks of essentialism in this way, and so counts
"maximal essentialism" but not "minimal
essentialism" as a form of essentialism. (It is natural to
suppose that Della Rocca thinks that essential properties are
non-trivial necessary properties, so that he can *say* things
like, "Essentialism is the view that some objects have some
essential properties." If this is what Della Rocca thinks, then
on his view, either the essential/accidental distinction is not exhaustive--since trivial necessary properties, like being such that there are infinitely many primes, are neither accidental nor essential--or the distinction is exhaustive but being such that there are infinitely many primes is counted an accidental property, contrary to intuition.)



The fourth position--according to which neither "minimal
essentialism" nor "maximal essentialism" counts as a
form of essentialism--is occupied by the characterization of
essentialism as



the view that the accidental/essential property distinction is robust
in the sense that (at least some) objects have (at least some)
non-trivial essential properties and (at least some) objects have (at
least some) accidental properties.




Yablo (1998) has this characterization in mind, and so he
characterizes both "minimal essentialism" and
"maximal essentialism" as forms of anti-essentialism.



In the remainder of this entry, essentialism will be understood in the
first of the four ways--so maximal essentialism and minimal
essentialism will both be viewed as forms of essentialism.


## 4. Some Varieties of Essentialism



A variety of particular forms of essentialism have been advocated.
Starting at one extreme, there is maximal essentialism. Although
Leibniz famously held this view, it nearly goes without saying that
this view has had relatively few adherents. According to a less
extreme and correspondingly more popular form of essentialism,
*origin essentialism*, an object could not have had a radically
different origin than it in fact had. The view that a particular table
could not have been originally made from completely different material
than the material from which it was actually originally made and the
view that a person could not have originated from a different sperm
and egg than those from which he or she actually originated are both
forms of origin essentialism. Origin essentialism has been defended by
Kripke (1972/1980) Salmon (1981), and Forbes (1985), among others.
According to another moderate form of essentialism, *sortal
essentialism*, an object could not have been of a radically
different kind--at least for certain kinds--than it in fact
is. Both the view that being human (or being human if existent) is an
essential property of Socrates and the view that Socrates could not
have been a credit card account are forms of sortal essentialism. The
mildest form of essentialism is minimal essentialism. Mackie (2006)
offers a sustained defense of roughly this view.



In addition to these sorts of claims about the essential properties of
ordinary individuals, claims about the essential properties of natural
kinds have figured prominently in the literature, since Kripke
(1972/1980) and Putnam (1975) made essentialist claims concerning, for
example, cats and water. The core intuitions are that in any possible
world anything that is not an animal is not a cat and that in any
possible world anything that is not composed of molecules of
H2O is not water. Since we discovered empirically that cats
are animals (and not, for example, robots) and that water is
H2O (and not some other type of molecule), each of these
claims asserts a necessary *a posteriori* connection between
two properties. In the first case, what is asserted is that it is
necessary that anything that is a cat is an animal. In the second
case, what is asserted is that necessarily anything that is (a sample
of) water is composed of molecules of
 H2O.[6]
 It is natural to construe these claims on the model of the
essentialist claims we have so far considered: it is essential to a
particular object, namely *the species cat*, to be such that
all of its instances are also instances of the kind animal; it is
essential to a particular object, namely *the kind water*, to
be such that all samples of it are composed of molecules of
H2O. Notice that one may hold that cats are essentially
animals in the sense that there is a necessary *a posteriori*
connection between the property of being a cat and the property of
being an animal, without holding that any particular cat is
essentially an animal. In other words, from the fact that it is
necessary that every individual that is a cat is an animal, it does
not follow that every individual that is in fact a cat is such that
necessarily it is an animal. In still other words, this type of
essentialism about natural kinds does not entail sortal
essentialism.



It is perhaps worth mentioning that similar remarks apply to the case
of a necessary *a priori* connection between properties. It is
a necessary *a priori* truth that all mathematicians are
rational. Following our model, we can say that it is essential to
*the kind mathematician* to be such that all of its instances
are also instances of *the kind rational (thing)*. It does not
follow that Andrew Wiles, who is in fact a mathematician, could not
fail to be rational--in which case he would also fail to be a
mathematician. To give an even more perspicuous example, it is a
necessary *a priori* truth that all bachelors are unmarried. It
does not follow that Michael, who is in fact a bachelor, could not be
married.



Philosophers have thought not only about whether an object has this or
that particular property essentially but also about whether an object
has a special kind of essential property, an *individual
essence*, a property that in addition to being essential to the
object is also unique to it in the sense that having that property is
modally sufficient for being that object (that is, it is not possible
that something distinct from that object has that property). A trivial
example of an individual essence is a *haecceity* or
*thisness* of an object, the property of being (identical to)
that very object. Some have defended the claim that there are
substantive examples of individual essences. Leibniz famously held
that there are, and that they can be given by purely qualitative
(general) properties. Forbes (1985) also holds that there are
substantive individual essences, but he disagrees with Leibniz that
they can be given by purely qualitative properties. Instead, he
thinks, an individual essence involves non-purely qualitative
(singular) properties: for example, Socrates's essence involves
originating from the particular sperm and egg from which he actually
originated. For more on modal sufficiency principles, see the



Supplement on Arguments for Origin Essentialism.
 


## 5. Suspicions about Essentialism



In SS3, we passed over without comment the parenthetical phrase
from Quine's characterization of essentialism. Adding that
phrase to the first view of essentialism from SS3 yields:



essentialism is the doctrine that (at least some) objects have
*independently of how they are referred to* (at least some)
essential properties.




The added phrase stresses that the essentialist thinks that it at
least makes sense to ask of an object ("in itself")
whether it must have a particular property. Skeptics about
essentialism have doubted the very intelligibility of such a question.
Here is one prominent thought behind such anti-essentialism. (See
Quine 1960, pp. 195-200.) Since it is necessary that seven plus two is
greater than seven, when the number nine is referred to as
'seven plus two' it is essentially greater than seven.
But, since it is not necessary that the number of planets is greater
than seven, when the number nine is referred to as 'the number
of planets' it is not essentially greater than seven. The point
is supposed to be that it makes no sense to say of the number nine,
independently of any way of referring to it, that it is or is not
essentially greater than seven. Similarly, an anti-essentialist might
say that when a person who is both a mathematician and a cyclist is
thought of as a mathematician, being rational is essential to him,
while being two-legged is not; but when the very same person is
thought of as a cyclist, then although being two-legged is essential
to him, being rational is not. Again, the point is supposed to be that
it makes no sense to say of the very person who is the mathematical
cyclist, independently of any way of thinking about him, that he is or
is not essentially rational (or two-legged). According to the
anti-essentialist, asking whether Andrew Wiles (who we may suppose is
a cycling mathematician) could fail to be rational is like asking
whether Andrew Wiles is taller than--both questions demand
another relatum. Could he fail to be rational, *relative to what
way of referring to him*? Is he taller than *whom*?



In response the essentialist will point out that the
anti-essentialist's thought does not square very well with
intuition. Consider the object that is referred to by all these
phrases: 'nine', 'seven plus two', 'the
number of planets'. Could *that very object* have failed
to be greater than seven? Intuitively the question seems intelligible,
and the answer seems to be that it could not have failed to be greater
than seven. According to intuition then, the very object that is
referred to by 'the number of planets' (which is the very
same object that is referred to by 'seven plus two' and
'nine') is essentially greater than seven. Intuition also
has it that the claim that the number of planets is greater than seven
is not itself necessary. To add some jargon: Intuition has it that the
claim that it is necessary that the number of planets is greater than
seven is true read *de re* ("of the thing"), but
false read *de dicto* ("of the dictum" or "of
the statement"). (The *de re* reading is this: the number
of planets has the property of being necessarily greater than seven.
The *de dicto* reading is this: the claim that the number of
planets is greater than seven has the property of being necessary.)
The essentialist is pointing out that the anti-essentialist's argument
asserts that the latter intuition undermines the former, but does not
say why.


## 6. The Epistemology of Essentialist Claims



Assuming that we have knowledge of some essentialist claims, how might
we account for that knowledge? For the purposes of the present
discussion, let us assume that we know that being such that there are
infinitely many primes, being human, and originating from sperm
\(s\) and egg \(e\) are essential properties of Socrates.
The first example is different from the last two in that it seems that
we can know *a priori* that being such that there are
infinitely many primes is essential to Socrates whereas it seems that
we can know only *a posteriori* that being human and
originating from \(s\) and \(e\) are also essential to
him.



While it is a vexed philosophical issue just how to account for *a
priori* knowledge of necessary truths such as logical truths,
mathematical truths, and the homelier necessary truths like the truth
that nothing can be red all over and green all over at the same time,
accounting for our knowledge of the necessary truth that Socrates is
such that there are infinitely many primes, does not seem to be
problematic in some extra special way. If we had a good account of our
*a priori* knowledge of the necessary truth that there are
infinitely many primes, then it would take little more to account for
our knowledge of the necessary truth about Socrates that he is such
that there are infinitely many primes.



Kripke (1972/1980) suggests that our knowledge of some other
essentialist claims is based in part on a bit of *a priori*
knowledge and in part on a bit of empirical knowledge. For example,
our knowledge that originating from \(s\) and \(e\) is
essential to Socrates is based in part on our *a priori*
knowledge that every organism has its origin essentially and in part
on our empirical knowledge that Socrates (is an organism that)
originated from \(s\) and \(e\). (Similarly our knowledge
that Socrates is essentially human appears to be based in part on our
*a priori* knowledge that everything has its kind essentially
and in part on our empirical knowledge that Socrates is (of the kind)
human.) Thus, our knowledge of the claim that originating from
\(s\) and \(e\) is essential to Socrates should be no more
problematic epistemologically than our knowledge of the two claims on
which it is based and our knowledge of the validity of the argument
from those two claims. As we have already mentioned, although there
are difficult philosophical issues concerning our knowledge of logical
truths, our knowledge of the validity of the argument in question does
not seem to add any special problems of its own. Similarly, although
there are philosophical issues concerning empirical knowledge, our
knowledge that Socrates originated from \(s\) and \(e\) does
not appear to add any special problems. However our *a priori*
knowledge that every organism has its origin essentially does seem to
have special problems over and above the problems associated with
accounting for our *a priori* knowledge of logic, mathematics,
and the homelier necessary truths. The latter claims are generally
supported by universally held intuitions or by arguments that are
universally accepted whereas the former, like most philosophical
claims, is supported by a less robust intuition and by a more
controversial argument. To see in some detail how philosophers have
gone about defending origin essentialism, see the



Supplement on Arguments for Origin Essentialism.
 



For more about arguments for sortal essentialism, see Wiggins (1980)
and Mackie (2006, chapters 7 and 8). The entry on
 the epistemology of modality
 is useful on general issues in modal epistemology.


## 7. Essentialist Claims in Arguments for Nonidentities



Leibniz's Law of the Indiscernibility of Identicals, according
to which, if "two" things are identical, then they share
all their properties, can be used to argue for various claims of
nonidentity. If you know, for example, that Charles is a philosophy
major and that Yoko is not, then you can safely infer that Charles is
not identical to Yoko. Essentialist claims have played a role in some
prominent Leibniz Law arguments for nonidentity theses. A certain
brand of mind-body dualism may be argued for in the following way:
\(X\) is essentially a thinking thing; \(X\)'s body is
not essentially a thinking thing; so \(X\) is not (identical to)
\(X\)'s body. A similar argument can be given for the
conclusion that a statue is not identical with the lump of material
(wax, clay, marble, or what have you) that constitutes it. Consider a
human-shaped statue--call it 'Goliath'--and the
lump of wax that composes it--call it
'Lump\(\_1\)'. Goliath, we may imagine, is throughout
its entire existence composed of Lump\(\_1\) while
Lump\(\_1\) throughout its entire existence composes Goliath. In
this case, Goliath and Lump\(\_1\) are *spatiotemporally
colocated*, which is just to say that they occupy the exact same
spatial region at any given time whenever either of them exists. This
being the case, they share most of their properties: Goliath weighs 17
kilograms and so does Lump\(\_1\); Goliath has a white surface
and so does Lump\(\_1\); and so on. In fact, it may seem curious
that we are writing as though there are *two things* at all.
Why not say simply that Goliath and Lump\(\_1\) are identical?
Well, it at least seems that a pretty straightforward
argument--one that relies on essentialist
claims--establishes their nonidentity:


1. Goliath is essentially human-shaped.
2. Lump\(\_1\) is not essentially human-shaped.
3. So, Goliath is not identical to Lump\(\_1\).



The plausibility of the two premises seems undeniable, given that we
think, for example, that if the room containing
Goliath/Lump\(\_1\) were to get really hot (hot enough to melt
the wax) and then to cool again (so that what was left was a lump of
wax in the shape of something like a mountain), then Goliath would be
destroyed while Lump\(\_1\) would still exist. And the reasoning
looks impeccable: if Goliath were Lump\(\_1\), then each would
have to have all of the same properties as "the other";
since they have different properties, they must not be identical. (Few
things in philosophy are as uncontroversial as Leibniz's Law of
the Indiscernibility of Identicals, though there has been some dispute
about the proper way of formulating it.) Figuring out how to reconcile
our intuitions that (1) and (2) are true with our tendency to think
that Goliath and Lump\(\_1\) are not really two things but just
one is a version of the *problem of material constitution.*
There are a wide variety of ways to deal with this problem. A
"two-thinger"--one who thinks that there really are
two things, a statue *and* a lump of wax, in one
location--may simply eschew the tendency to identify Goliath and
Lump\(\_1\). Other responses suggest that there is something
amiss with Leibniz Law arguments for nonidentities when there is this
kind of an appeal to essential properties: Della Rocca (1996c) holds
that such arguments are question begging; Lewis (1971) and Noonan
(1991) hold that they are invalid; and Burke (1994) and Rea (2000)
hold that in any such argument, at least one of the premises is false.
For those who are interested, Rea (1997) is a good place to start to
delve more deeply into this problem.