Is Locke a conceptualist or a
nominalist? Numerous supporters of these two opposing interpretative
hypotheses are to be found amongst scholars, and Locke's concept of
universals is the subject of reconstructions which often differ greatly.
In a situation of this sort, it is easy to yield to the temptation to
attribute the origin of the divergence to a purely terminological
ambiguity. Perhaps the word "nominalism" is understood in
different senses? Apparently not. Almost all writers, explicitly or
implicitly, agree in considering nominalism to be a doctrine according to
which universals exist only as names which are used to designate
collections of concrete individuals. Thus, according to nominalism, there
are universal terms (common nouns) and there are neither universal
entities which exist in reality (for all existing things are particular),
nor abstract, universal ideas existing in the mind. In modern philosophy
the positions of Berkeley and Hume are generally considered nominalist.
According to various scholars, Locke's position is essentially the same as
the nominalism of Berkeley. This interpretation is based principally on
Locke's assertions in paragraph 9, chapter xi, Book II, of An Essay
Concerning Human Understanding.
"…the mind makes the particular ideas, received from particular
objects, to become general; which is done by considering them as they are
in the mind such appearances, separate from all other existences, and the
circumstances of real existence, as time, place, or any other concomitant
ideas. This is called abstraction, whereby ideas taken from particular
beings, become general representatives of all of the same kind; and their
names, general names, applicable to whatever exists conformable to such
To prove this thesis, Locke uses the idea of whiteness as an explanatory
example: the white observed in milk is considered as a representative of
the same colour received from chalk or snow, if it has been separated, by
a mental operation, from other simple ideas with which it was before
If one considers this paragraph in isolation from the rest of Book II and,
especially, from the content of Book III, the following conclusions may be
a) Notwithstanding Locke's numerous references to the possession and
awareness of abstract or general ideas on the part of the human mind,
these abstract ideas are none other than particular ideas used as
representatives of or signs standing for a class of individuals: what is
universal is only the name.
b) The abstraction to which Locke refers corresponds to that which the
Scholastics called "improper" or distinguishing, which consists
in mentally separating a characteristic, a quality or a part of a known
thing from all of the others contemporaneously perceived; this kind of
abstraction is radically different from that which is "proper"
or non-distinguishing and which allows us to experience the (universal)
nature or essence in the perception of the particular.
c) Locke's conception of abstraction would not therefore be incompatible
with that of Berkeley; on the contrary, Berkeley's attribution to Locke of
a belief in the existence in the mind of general, abstract ideas in
reality distinct from particular ideas would seem a polemical exaggeration.
These considerations would make plausible Locke's classification as a
nominalist (for instance, John Yolton, argues that Locke's theory about
general ideas is in fact quite similar to Berkeley's own account and he
claims that, for Locke, abstract or general ideas are fictions ). In my
opinion, these would be incorrect and inadequate interpretations of
Locke's epistemology, based upon an arbitrary isolation of the text cited
above from the rest of An Essay Concerning Human Understanding. It should
be noted that:
1) The principal aim of Book II is to demonstrate that all of man's ideas
come from experience and that complex ideas are based upon the simple
ideas due to sensation and reflection, which are compared and combined by
operations of the mind. From this point of view, the distinction between
particular and universal ideas is of marginal importance. In fact, Locke
warns at the beginning of Book I that he will use the term idea "to
express whatever is meant by phantasm, notion, species, or whatever it is,
which the mind can be employed about in thinking" (I,i,8), and hence
includes in the semantic category "idea" both individual mental
representations (images and phantasms) and universals (notions and species).
2) As Locke explicitly states, the examples given in chapter xi of Book II
(which deals with mental operations), "the instances, I have hitherto
given, have been chiefly in simple ideas"; chosen, that is, for the
purpose of clarity and to further the aim of Book II, with the explicit
warning that "Of compounding, comparing, abstracting, etc. I have but
just spoken, having occasion to treat of them more at large in other
places" (II, xi,14).
3) In Book III, Locke states that
"the sorting (…) under names is the workmanship of the
understanding, taking occasion from the similitude it observes amongst
them, to make abstract general ideas, and set them up in the mind, with
names annexed to them, as patterns, or forms, (…) to which, as
particular things existing are found to agree, so they come to be of that
species, have that denomination, or are put into that classis. (…) And
when general names have any connexion with particular beings, these
abstract ideas are the medium that unites them: so that the essences of
species, as distinguished and denominated by us, neither are, nor can be
any thing but those precise abstract ideas we have in our minds"(III,
This text is not ambiguous: although for Locke abstract ideas are the
connection between general terms and particular things (which are known by
means of ideas), it is clear that the link (medium) cannot be identified
with either of the two elements which it connects: an abstract idea cannot
be a particular used as though it were a universal. In other words, that
which determines the universality of an abstract idea for Locke is not
simply its relation with a number of particular ideas, as for Berkley, but
something inherent in and characteristic of the idea itself, the nominal
essence which distinguishes all complex ideas (all kinds of complex ideas:
of modes, relations and substances).
As far as simple ideas are concerned, Locke thinks that the names of
simple ideas, and those only, are incapable of being defined, because what
distinguishes simple ideas is that they are not analysable into component
ideas. This Locke's thesis is not inconsistent with a careful distinction
between simple abstract idea and simple particular idea, between the
concept of green and the percept of green as individual mental
representation (this green I see) or the image of green. Therefore which
determines the universality of an abstract idea is something
characteristic of idea itself as well for simple ideas.
In both these kinds of general idea (of complex and simple idea), the idea
is universal in its own nature, i.e. it is made general by abstraction and
it, unlike the particular ideas from which it was abstracted, is capable
of serving as a standard by which to rank real existences. This might seem
a violation of the fundamental principle of Locke's nominalistic
metaphysics, the principle that all existing things are particular. But,
as Vere Chappell says, it is not really so:
"For this principle applies only to the realm of real existence. This
includes physical objects, and their qualities, which are outside people's
minds; and it includes the actions and events that occur within minds,
includes acts of perception and thought. But it does not include the
intentional objects of such acts, which is what ideas are according to
I do not think that there are evident contradictions between the examples
of abstraction given in Book II and the broad theory of language presented
in Book III. There is simply a difference of approach and aims and thus,
in the final analysis, a complementarity.
This claim is consistent with R.I.Aaron's view about Locke's abstract
ideas theory. Aaron gives the following account of Locke's theory: the
general character of Locke's theory of universals "is not a fully
integrated theory ,yet it points steadily in one direction, namely,
conceptualism. Realism is rejected; the universal is never one entity
amongst others in the world of existences, nor is it a real essence…
Locke's theory excludes nominalism as well as realism" .
Aaron finds three doctrines of abstraction in Locke's Essay :
1) an abstract idea is a particular idea which "represents" many
other particulars; it was Locke's first crude thought (and the Berkeley of
The Principles reverted to a point of view long since abandoned by Locke);
2) an abstract idea is what remains when, from a number of particular
ideas, all features except those which are common have been dropped from
attention (this doctrine is predominant in Book II);
3) an abstract idea is the essence meant when the general term is used;
this doctrine is capable of including within itself the second doctrine
and it is predominant in Book III. Considering the progressive development
evident in Locke's thought throughout the Essay, his later position
represents his more mature thought.
Greatly widespread amongst scholars is the legend according to which Locke
shows a strong aversion to abstract ideas, similar to that of Berkley in
the Treatise. This legend is endorsed by influential commentators on
Locke. A. C. Fraser writes:
"Locke has everywhere a sober dread of abstractions, and clings to
the particular and concrete, with a sense of the risk of losing the real
in the emptiness of the universal" .
In reality this supposed aversion does not exist; on the contrary, Locke
does not even propose the reduction of ideas to "mental images"
(a reduction which in Berkeley and Hume will form the base of the negation
of the existence of abstract ideas in the mind).
Locke is not in the least afraid of abstract ideas; his constant concern,
which is evident in his treatment of the complex question of the relation
between real and nominal essence, is to refute the view of the Scholastics,
according to which a universal concept in the mind (post rem) reflects the
universal present in all things as substantial form (the universal in re),
without assuming positions which are purely conventionalist and nominalist
with regard to knowledge, such as those of Mersenne, Gassendi, Hobbes and
sceptical and anti-Cartesian free-thinkers.
According to the view of the Scholastic in seventeenth century, as in the
Aristotelian hylemorphic account of material things, all the individuals
in the same sort are determined by an identical form ( differences among
individuals are determined by the "materia signata") and the
real essence of every individuals of the sort is immutable, because it is
created by God. R.L. Amstrong writes:
"for a traditional metaphysician like Sergeant, the relation between
external objects and the knowledge of them in the mind is identity; the
notion in the mind is the very thing itself, its form."
On the contrary, according to Locke, "take but away the abstract
ideas by which we sort individuals and rank them under common names, and
then the thought of anything essential to any instantly vanishes" (III,
vi, 4). According to Locke, there are no essential properties, no
identical substantial form in all the individuals in the same kind or
specie and therefore abstract ideas are made by the mind and not by
nature: "particular beings, considered barely in themselves, will be
found to have all their qualities equally essential; and everything in
each individual will be essential to it or, which is more, nothing at all."
(III; vi, 5) And again:
"general and universal belong not to real existence of things; but
are the invention and creatures of the understanding, made by it for its
own use, and concern only signs, whether words, or ideas (…)
universality belongs not to things themselves, which are all of them
particular in their existence, even those words, and ideas, which in their
signification, are general" (III, iii, 11).
To show why Locke's view of knowledge is not a conventionalist one, I must
offer an analysis of the relation Locke makes between real and nominal
essence, with regard to the relations which link term to idea and idea to
things. For Locke, the term is the sign (mark) of an abstract idea and the
idea itself is the sign of a plurality of things.
The relation between the name and the idea is, in the final analysis,
"…words, which were by nature so well adapted to that purpose, came
to be made use of by men, as the signs of their ideas; not by any natural
connexion, that there is between particular articulate sounds and certain
ideas (…); but by a voluntary imposition, whereby such a word is made
arbitrarily the mark of such an idea. The use then of words, is to be
sensible marks of ideas…"(III, ii, 1).
The nature of the relation between signifier and signified is variable,
though, in the relation between ideas and things with respect to the
various kinds of complex ideas which the human mind may frame. The
greatest difference is to be found between complex ideas of mixed mode and
complex ideas of substance. With regard to the essences "of the
species of mixed mode", Locke points out that they "are not only
made by the mind, but made very arbitrarily, made without patterns, or
reference to any real existence." (III, v, 3).
With regard to ideas of substance in particular, Locke's thought is
interpreted in different and often contradictory ways. Although complex
ideas of substance may be reduced to a collection of simple ideas, Locke
does not doubt the existence of "the real internal, but generally in
substances unknown constitution of things, whereon their discoverable
qualities depend" (III,iii,15). The reference of the idea (universal)
to things is uniquely determined by the nominal, not the real, essence:
"our faculties carry us no farther towards the knowledge and
distinction of substances, than a collection of those sensible ideas,
which we observe in them; which, however made with the greatest diligence
and exactness, we are capable of, yet is more remote from the true
internal constitution, from which those qualities flow, than, as I said, a
countryman's idea is from the inward contrivance of the famous clock at
Strasbourg, whereof he only sees the outward figure and motions" (III,
Locke insists that nominal essences are not arbitrary because the mind, in
forming its complex ideas of substances "only follows nature"
and does not join together ideas which do not have a natural connection.
For Locke, man uses a certain discretion in constructing nominal essences,
since he chooses perceived qualities considered characteristic of a
substance, but this discretion is not arbitrary or unconditional because
it is limited to the occurrence of empirically verifiable properties,
increasingly so by the growth of the scientific knowledge of nature,
although clearly this discretion is never completely eliminated since
human knowledge may always be perfected. In Book II, Locke asserts that
ideas of substance are all inadequate because they all lack "something
we should be glad were in them", since "desiring to copy things,
as they really do exist; and to represent to our selves that constitution,
on which all their properties depend, we perceive our ideas attain not
that perfection we intend" (II,xxxi,3), but this perfection (the
complete identity of real essence and nominal essence) may never be
reached. On the other hand, complex ideas of mixed mode and of relations
are always adequate (for Locke an idea is adequate if it represents
perfectly the archetype on which the mind supposes it is based).
Many scholars attack Locke's underlying assumption that the nominal
essence of complex ideas of substance are not arbitrary. For instance,
Robert Anderson acknowledges that according to Locke "man making
abstract ideas, and settling them in their minds with names annexed to
them, do thereby enable themselves to consider things, and discourse of
them, as it were in bundles…" (III, iii, 20) but he holds that
"in the light of Locke's reflections in Book IV, it now appears that
nominal essence cannot preserve this utility and this partial conformity
to things. For it now seems that there is nothing truly essential to
material things, and that they have, indeed, no real essence" . A
similar view is also shared in Italy by Lia Formigari and Rocco Pititto,
who claim that, according to Locke, the ideas of substances are in the
final analysis arbitrary.
Locke's claims (in chapter vi, Book IV) about unknowability of real
essence seem to corroborate Anderson's view. For instance, about the real
essence of gold
"we have no idea at all. This being as impossible for us to know, as
it is for a blind man to tell in what flower the colour of a pansy is, or
not to be found" (IV, vi, 5).
Nevertheless one must underline that the goal of the chapter cited above,
in which Locke deals with the truth and certainty of universal
propositions, proves that scientific statements about physical objects are
not certain. According to Locke only trifling propositions, mathematical
and ethical statements are certain. Therefore one can not answer the
question about the knowability of real essence basing only on the cited
chapter in Book IV: one must consider more entirely Locke's thought in
Book II, III and IV of the Essay.
According to Locke an identical form or essence determining all
individuals in the same sort does not exist. There is a real essence of
this piece of gold or of that cat, but there is not, in the strict sense,
a real essence of gold; hence any universal term has only the nominal
essence. Nevertheless it is clear and evident that Locke also uses the
locution "real essence" with reference to universal ideas,
because he deals with the relation between real essence and nominal one.
The reference of ideas to things is not as easy a matter as determining
the biunivocal relationship between the constituent elements of a complex
idea and the corresponding simple ideas themselves, because the
relationship of concomitance of simple ideas and the persistence of this
concomitance must be considered. In this sense one can speak of real
essence of abstract ideas of substances, as the limit and the ultimate
goal to which human knowledge of reality is tending.
One may ask a fundamental question: this unknowability of real essence of
a substance which has been asserted by Locke on numerous occasions, is it
an unknowability in principal (absolute impossibility) or an unknowability
in practice, due to the limitations of science at the time?
Although the question cannot be resolved once and for all, I am convinced
that from the overall spirit of the Essay there emerges the idea that
human knowledge tends to conform to an objective structure of reality;
even though Locke is aware that the complete identity between nominal and
real essence is impossible in practice with respect to the knowledge of
substances, he remains convinced that this identity constitutes the limit
and the ultimate goal of the quest for knowledge.
Locke is aware that the science of his time is inadequate:
"…we are so far from being admitted into the secrets of nature,
that we scarce so much as ever approach the first entrance towards them."
The reasons for this are two: the complexity of the relations between a
physical object and all other bodies escapes the scientific knowledge (IV.vi,11)
and the human mind can not understand the relations between the
alterations of primary qualities and the secondary qualities we received
by the five senses (IV,vi,7).
"We cannot discover so much as that size, figure, and texture of
their minute and active parts, which is really in them; much less the
different motions and impulse made in and upon them by bodies from without,
upon which depends, and by which is formed the greatest and most
remarkable part of those qualities we observe in them, and of which our
complex ideas of them are made up. This consideration alone is enough to
put an end to all our hopes having the ideas of their real essence" (IV,vi,12).
But he adds:
"our ideas of substance, which consisting of a collection of simple
ideas, supposed taken from the works of nature, may yet vary from them, by
having more or different ideas united in them, than are to be found united
in the things themselves: from whence it comes to pass, that they may, and
often do fail of being exactly conformable to things themselves." (IV,iv,11).
It should be noted that Locke writes: "they may (emphasis added) fail
of being exactly conformable"; actually they do fail, but in
principal it is possible for them not to fail, i.e. they could be exactly
conformable to things themselves. The very instance of the famous clock at
Strasbourg, cited by Locke on numerous occasions, fully bears out this
view: the inward contrivance (which stands for the real essence in the
metaphor) is unknown by the countrymen, who only observe the external
visible movements, because they are unacquainted with the laws of
mechanics. According to Locke, a knowledge of substances as a sheer and
arbitrary collection of simple ideas is surely diffused, but it
corresponds to a superficial and pre-scientific kind of knowledge.
Locke's analysis of the knowledge of substances in Book III and IV anyhow
does not make void the criticism to the concept of substance in Book II.
According to Locke the substances are not the ultimate constituent of the
matter, but they are the link between the continuum of matter and the
discontinuous we experienced through the five senses.
According to Locke the very reality is set up by mechanical phenomena,
i.e. by the frame of primary qualities of matter which cause all sensitive
distinctive features of things: hence the substances are only the discrete
results of human operations of "cutting" the continuum of matter;
operations made by the human mind to seek and to isolate comparatively
permanent forms of mechanical equilibrium, which marks are the secondary
There is, in effect, in Locke's thought a break with the Cartesian view of
science: mathematics and demonstration are no longer the only privileged
model of knowledge; experiment regains the essential role that Descartes
denied it. For Locke, who was a great admirer of Newton, mechanical
explanation remains the ideal model for a scientific explanation, but it
is not always - in practice - possible (Boyle was also convinced of this)
and so the knowledge of nature assumes a merely probable status, having
been reached by the process of induction, in contrast to mathematics and
ethics which are completely deductive. In fact, Boyle's research and
methods had a profound influence on Locke's conception of science and in
particular on the doctrine of the knowledge of substances. These
observations on Locke's philosophy of science underline the enormous,
unbridgeable distance between it and that which Berkeley was to formulate
in De Motu in 1721 (defined as "instrumentalist" by K. Popper,
as opposed to the "essentialism" of Newtonian physics).
In conclusion, in opposition to other widespread opinions, I claim that:
1) Locke's concept of abstraction is fully compatible with conceptualism
and may in no way be considered nominalist; 2) Locke's complex theory of
knowledge cannot be considered a conventionalist view of science.
Furthermore, the profundity of Locke's concept of substance with regard to
the science of his time will clearly emerge, so as to make evident the
inadequacy of Hegel's judgement in conclusion of his comment on the
distinction between real and nominal essence in Locke, which finishes with
the famous phrase:
"This (philosophising) is a very commonplace account of the matter".
Oxford, April 4th , 2004
(Tercentenary John Locke Conference, St. Anne's
College, University of Oxford, 2-4 April 2004)
The footnotes can be read in pdf or word version of this