On Two Seeing the Same Thing: Hylas Was Right
1. Introduction
In the Third Dialogue, there is this exchange:
HYLAS: Is it not your opinion that by our senses we perceive only the
ideas existing in our minds?
PHILONOUS: It is.
HYLAS: But the same idea which is in my mind, cannot be in yours, or in
any other mind. Doth it not therefore follow from your principles, that no
two can see the same thing? And is not this highly absurd? (W2: 247)
Here Hylas argues that Berkeley’s position has the absurd consequence that objects are not
publicly perceivable. Instead they, like the ideas or sensations that constitute them, are
perceivable by only a single mind; like an after-image or a toothache, they are private, or
accessible only to one person. Such a consequence would ruin Berkeley’s claim that his idealism
can be reconciled with common sense. Further, it would be virtually a reductio ad absurdum of
his idealism, for it amounts to saying that there is no common world of objects; rather, there are
as many distinct, self-enclosed, private worlds as there are perceivers. In this paper I argue,
against some recent commentators, that Berkeley is really committed to this consequence.
2. The no-shared-ideas principle
Hylas’s argument in the above exchange can be put as follows:
(1) Objects are merely collections of ideas.
(2) No idea can be perceived by two or more minds.
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 (3) No object can be perceived by two or more minds.
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Philonous accepts the first premise. The second, key premise, which I shall call the “noshared-ideas principle,” generalizes Hylas’s statement that “the same idea which is in my
mind, cannot be in yours, or in any other mind.”
The no-shared-ideas principle is highly plausible. Consider for example a mental
image, such as the one you might form when you shut your eyes and visualize a beach. It is
obvious that no other person could have this very mental image. Someone else could
conceivably have a mental image just like yours, a mental image that “looks” just like
yours, but no one else could have the very mental image that you have. Someone else could
have a mental image that was qualitatively the same as yours, but no one could have
numerically the same mental image as yours.i
This example may seem unfair to Berkeley. For a mental image is not, by
Berkeley’s lights, an idea of sense; rather, it is an idea of the imagination—a “creature of
the mind,” an idea “of our own framing,” which Berkeley would presumably agree, or
certainly ought to agree on pain of lapsing into plain falsehood, is private to the person who
has it. But, it may be said, this does not mean that ideas of sense—those that for Berkeley
constitute bodies--are also private in this sense. Perhaps ideas of sense, unlike ideas of
imagination and their kin, are publicly perceivable.
To assess this possible defense of Berkeley, recall the differences between ideas of
sense and “creatures of the mind.” There are two such differences: (1) ideas of sense are
more orderly, consistent, or regular than mere figments, and (2) ideas of sense are
“imprinted” on us by God. (Sometimes, Berkeley also says that ideas of sense are “more
strong” or “vivid” than other ideas.) Does this mean that an idea of sense, unlike a mere
mental image, is publicly perceivable? No. For although an idea of sense is related to other
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ideas differently than a mental image, and caused by a different spirit than a mental image,
its metaphysical status is the same as that of a mental image; nor does it make any
difference whether an idea of sense is also more strong or vivid than a mental image.
Berkeley himself seems to admit as much when he says:
The ideas of sense are allowed to have more reality in them, that is, to be
more strong, orderly, and coherent than the creatures of the mind; but this
is no argument that they exist without the mind. They are also less
dependent on the spirit, or thinking substance which perceives them, in
that they are excited by the will of another and more powerful spirit: yet
still they are ideas, and certainly no idea, whether faint or strong, can exist
otherwise than in a mind perceiving it …. There is a rerum natura, and the
distinction between realities and chimeras retains its full force. This is
evident from Sect. 29, 30, and 33, where we have shewn what is meant by
real things in opposition to chimeras, or ideas of our own framing; but
then they both equally exist in the mind, and in that sense they are alike
ideas. (PHK 33, 34)
To be sure, this passage does not explicitly say that ideas of sense are private, but it does
imply that they have the same status as “chimeras, or ideas of our own framing,” which are
private.
Significantly, there is at least one passage, which Berkeley commentators have
surprisingly not connected (so far as I know) to the privacy issue despite its clear bearing on
that issue, where Berkeley does explicitly acknowledges the privacy of ideas of sense, even
if somewhat obliquely:
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As we conceive the ideas that are in the minds of other spirits by means of
our own, which we suppose to be resemblances of them: so we know other
spirits by means of our own soul, which in that sense is the image or idea
of them, it having a like respect to other spirits, that blueness or heat by
me perceived has to those ideas perceived by another. (PHK 140)
Berkeley’s purpose in this passage is to explain how we conceive of other minds: our own
soul is in a loose sense an “image” or “idea” of other minds. But the passage also shows
that, here at least, he grants that the same ideas of sense are not perceived by two different
minds. For he says that the idea of blueness or heat that I perceive stands in the same
relationship to the idea of blueness or heat that you perceive as does my mind to your mind:
and this relationship is plainly not the relationship of identity (Berkeley suggests that it is
more akin to resemblance). Indeed, Berkeley also explicitly says that we “suppose” our
ideas to be “resemblances of” other peoples’ ideas. This supposition, which he is here
endorsing as well as reporting, implies again that one person’s ideas are not the very same
ones as another person’s ideas. Thus, Berkeley seems by his own admission to be
committed to the no-shared-ideas principle.
It has seemed to some commentators, however, that regardless of whether Berkeley
ever conceded the no-shared-ideas principle, there are in fact good Berkelian arguments for
its denial, which we may call the “shared-ideas thesis.” Thus David Berman writes:
Consider the question which Berkeley asks in Commentaries, entry 645:
‘Qu: whether there can be Volition without perception’; to which he
answers some thirty entries later: ‘Distinct from or without perception
there is no Volition’ (no. 674). I take this to mean that a mind cannot will,
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cause, or create an idea without perceiving the idea it creates. How could
one create an imaginative idea of a red dot, for example, without
perceiving it? And if we can judge God’s mental activity by analogy with
our own—which we are entitled to do, according to Berkeley (Works, ii.
231)—then we may assume that God, too, must perceive the ideas he
creates in finite minds. As Berkeley states in the Three Dialogues:
‘whatever ideas we perceive from without are in the mind that affects us’
(Works, ii. 240). Yet if God is aware of the idea he creates in my mind,
then he and I are aware of the numerically same idea. To assert the
contrary seems to imply that God creates an idea of which he is not aware,
that he is an absolute creator but, at best, only a relative perceiver. Such a
view seems mistaken, if only because it limits God’s omniscience. Yet if
God and I can perceive the same idea, then there seems no insuperable
reason why God cannot create and perceive the same idea in other finite
minds.ii
I don’t think that this argument works. Suppose that I desire or “will” that you think about
my favorite work of art, say Picasso’s Guernica. I grant that, in accordance with the denial
of blind agency, I must then have an idea of Guernica in mind. Now suppose also that, at
the very time I desire that you have an idea of Guernica in mind, you do have such an idea.
Does it follow that the idea of Guernica that exists in your mind is “numerically identical”
with the idea of Guernica that exists in my mind? No. All that follows is that the content of
our ideas must be (at least approximately) the same—i.e. that our ideas must be
qualitatively (at least approximately) the same. But the only relevant difference between
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this case and a case involving God is that God, unlike myself, can cause you to have any
idea he wants you to have by a simple act of His will. Does this added factor, of God’s
extraordinary power to cause an idea of X telepathically, mean that the idea of X that He so
causes in you is numerically identical with the idea of X that He must have in mind in order
to will to produce an idea of X in you? I think the answer is no.
Is there a better argument for the shared-ideas thesis? Well, Berkeley holds that God
perceives all ideas. So, it may be argued that when a given finite mind, call it M1, perceives
any idea, that idea is identical with one of God’s ideas. Thus, we already have a case where
one idea can be in two minds, God’s mind and finite mind M1. I shall call the proposition
that an idea in God’s mind can be identical with an idea in a finite mind, the “divine/nondivine idea identity claim” (DNIC). DNIC contradicts the no-shared-ideas principle. But
there is more. If an idea can be in both M1 and in God’s mind, then (as Berman point out)
there is no reason why that idea cannot also be in another finite mind, M2. But if an idea in
M1 can be identical with an idea in God’s mind and that idea of God’s can be identical with
an idea in M2, then, by the transitivity of identity, an idea in M1 can be identical with an
idea in M2, and so the no-shared-ideas principle is false even as applied to finite minds. I
shall call this reasoning the “transitivity argument.”iii
One problem for the transitivity argument is a purely historical one: Berkeley
himself seems to have rejected DNIC. Malebranche held precisely that we perceive God’s
ideas. Malebranche also held that God’s ideas represent a material world, though they are
not caused by material things but rather by God. Berkeley accepted the view that (most of)
our ideas are caused by God, but he rejected both Malebranche’s material world and, more
to the point here, Malebranche’s view that we perceive God’s ideas. In the Second
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Dialogue, Philonous takes pains to distance himself from what he calls “the opinion that we
see all things God,” which he stigmatizes as “the enthusiasm of Malebranche,” from which,
he adds, “I am very remote” (W2: 214). It seems, then, that Berkeley himself rejected
DNIC.
But putting aside this historical point, I don’t think that the transitivity argument
works. For its key premise—that God perceives all ideas (so that he must perceive all finite
minds’ ideas)—need not be taken as strictly as the argument requires it to be. It may mean
only that God has knowledge of all our ideas by having His own ideas of our ideas.
Berkeley uses “perceives” in a broad sense, on which it sometimes only means that one
knows or comprehends that which is said to be “perceived.” So, God could “perceive” our
ideas by having divine counterparts of them; and being omniscient, He would know that
they are counterparts. (This may well be the sense in which God “perceives” our ideas of
sense, since he does not perceive them by sense but in a purely intellectual way.) It might
be thought that this scenario is incompatible with God’s omniscience because, while it
allows that he has “knowledge by description” of our ideas, it denies that he has
“knowledge by acquaintance” of them. But if God’s divine ideas are perfect representations
of their objects, as they must be, then no further knowledge of those objects can be gained
by the mere confrontation with them that acquaintance presumably involves. Indeed, I
would argue that the bare confrontation with an idea that would constitute acquaintance
with it is not a species of knowledge at all, so that its absence cannot count against God’s
omniscience.
3. Against the divine/non-divine idea identity claim
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So far I have (a) appealed to mental images to argue for the no-shared-ideas
principle, (b) given textual evidence from the Principles that Berkeley accepts the noshared-ideas principle, (c) faulted Berman’s argument purporting to show that Berkeley is
committed to the shared-ideas thesis, (d) given textual evidence from the Second Dialogue
that Berkeley rejected DNIC, and (e) faulted the transitivity argument for holding that
Berkeley is committed to the shared-ideas thesis. I now wish to go one step further, and to
argue that DNIC, which is fundamental to the two arguments that I have discussed against
the no-shared-ideas principle, is both inconsistent with Berkeley’s views and
philosophically untenable.
It is not easy to give a convincing argument against DNIC. It will not do, for
example, to argue that since God’s ideas are eternal and our ideas are not eternal, our ideas
cannot be identical with God’s ideas. For a proponent of DNIC can reply that since our
ideas are identical with God’s ideas and God’s ideas are eternal, it follows that our ideas are
eternal too, even though we do not perceive them eternally (only God does that). But now
an argument against DNIC suggests itself. If an idea of God’s belongs also to a finite mind,
and if there are times when that finite mind does not perceive this idea, then this idea
belongs to a finite mind even at times when that mind does not perceive the idea--when the
idea is not “in” that mind, in the Berkeleian sense of being perceived by that mind. This is
because if an idea, I, belongs to a finite mind at a time t, then I must continue to belong to
that mind at all times when I exists; it cannot “migrate,” as it were, to some other mind. For
an idea is “of” or “belongs to” a subject in somewhat the same way that a state or condition
is “of” or “belongs” to a thing. If one person catches a cold from another person, then we do
not say that it is numerically the same cold that the second person has.iv Furthermore,
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conscious states such as ideas are essentially subjective, in the sense that every mental state
exists for some particular subject, so that it is essential to a particular mental state that it
exists for the very subject for whom it exists. Thus, an idea cannot be the very idea that it is
without existing for the very individual for whom it is an idea.v Now according to DNIC,
any idea perceived by a finite mind can also be an idea in God’s mind. But surely some
such ideas are not perceived at all times by that finite mind, if only because a finite mind,
even if we assume it to be immortal, does not have the capacity to perceive simultaneously
and at all times all the ideas it will ever perceive. Thus, a proponent of DNIC must say that
I, or any finite mind, can have an idea at a time t—that the idea can be my idea at t, or
belong to me at t, even though I do not perceive it at t, even though I am not aware of it at t;
he must say that an idea can belong to a finite mind even though it is not “in” that mind, in
Berkeley’s sense of being perceived by that mind. But this consequence is both utterly unBerkeleian and philosophically untenable. Berkeley recognizes no sense in which an idea
can belong to a mind when it is not “in” that mind in his sense of being perceived by it, and
the suggestion that an idea could belong to a mind when that mind is unaware of it is quite
unintelligible, at least if we think of ideas as conscious episodes rather than as dispositions
of some sort.
It will not do to respond to this argument by saying that God’s ideas are identical
with a finite mind’s, and thus belong also to that finite mind, only at those times when the
finite mind perceives those ideas, but not at other times. For the divine ideas that are
supposed to be identical with ideas in finite minds exist at all times, so that the ideas in the
finite minds must also exist at all times. But if X is identical with Y, then X remains
identical with Y at all times when X and Y both exist. Nor will it do to respond by saying
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that God’s ideas are not “eternal” in the sense that they exist at all times, but in the sense
that they exist outside of time altogether. For even if one believes (as I do not) that the
notion of an idea’s existence outside of time is intelligible, our ideas unquestionably do
exist in time, and what exists outside of time cannot be identical with what exists in time.vi4
4. Consequences of the no-shared-ideas principle
I have argued that Berkeley is committed to both premises of this argument:
(1) Objects are merely collections of ideas.
(2) No idea can be perceived by two or more minds.
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 (3) No object can be perceived by two or more minds.
Berkeley, however, could legitimately object that this argument is not valid—that (3) does
not really follow from (1) and (2). The reason is twofold. First, in order to perceive an
object, one need not perceive every part of it. I can see the Queen Mary by seeing her bow,
I can see my wife by seeing her face, and I can see a cat by seeing its tail. Second, an object
could be composed of many different peoples’ ideas, e.g. partly of my ideas, partly of
yours, partly of a third person’s, etc. Indeed, this seems to be Berkeley’s own view, since he
holds that I do not at any time perceive all the ideas that constitute an object, so that the
others must be perceived by some other mind(s), if only by God. But in light of these two
points, we can see that despite (1) and (2), different people could perceive the same object.
They need only each perceive different parts--“their” parts, so to speak--of that object.
This reply, however, does not dispose of the basic difficulty. For Berkeley’s view
still entails that the constituent elements of an object are not publicly perceivable. This is
because the above argument can be converted into a valid one, as follows:
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(1') The constituent elements of an object are merely ideas.
(2) No idea can be perceived by two or more different minds.
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 (3') No constituent element of an object can be perceived by two or
more different minds.
Again, Berkeley is committed to both premises. But (3') is very paradoxical: it seems
absurd to hold that objects (i.e., the objects that Berkeley equates with bodies or “real
things”) are composed of elements none of which can be perceived by more than one mind.
Furthermore, the following proposition seems to be a conceptual truth:
(4) If no constituent element of an object can be perceived by two or more
minds, then no object can be perceived by two or more different minds.
But then (3') leads back to (3), since (4) and (3') and entail (3).
George Pappas, however, has argued even if one concedes (3') (which he does not),
one cannot derive (3), because (4) is in fact not a necessary truth. He writes:
[The] argument rests on the assumption that if two people do not
immediately perceive the same constituents of an object, or perhaps if
those two people cannot immediately perceive the same constituents, then
they do not immediately perceive the same object. To test this assumption
we can imagine a case of two people looking on either side of a large
wooden fence, and suppose that each is looking at the fence. We would
say, I think, that each person sees the fence, even though each is seeing
different parts of the fence. Of course, this example is not exactly
analogous to Berkeley’s account, because … ideas are not parts of
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[Berkeleian] physical objects. However, [a] general on the reviewing stand
example will suffice to make the point here. That is, two generals on
different sections of the reviewing stand, may see different members of the
troop, but each would see the troop. Two people can see the same object
though they do not see the same parts or constituent elements of the
object.vii
Thus, Pappas could say that (3'), even though he does not accept it, is not as bad as (3), for
(3'), unlike (3), allows that two or more minds could perceive the same object.
I do not think that Pappas succeeds in showing that even if Berkeley is committed
to (3'), he can escape the consequence that objects are not publicly perceivable. Notice
first that public observability, or intersubjective perceivability, is an essential element in
the conception of an object. From the point of view of common sense, what marks an
object off from a mere creature of the mind is that it exists independently of the mind and
that it is publicly perceivable. Thus, if we think of objects, with Berkeley, as being
ontologically dependent on minds, then it is all the more crucial that we still be able to
think of them as publicly perceivable: otherwise, we deprive ourselves of whatever
justification, if any, is left for calling them objects. Thus, it is crucial for Berkeley to
provide a plausible account of how more than one mind can perceive the same object.
Now the basic intuition in Pappas’s defense of Berkeley is the claim that to perceive an
object, we need only perceive some proper part of it—that we can perceive an object by
perceiving a proper part of it. This is the point of his example of seeing a fence by seeing
one of its sides. But what lies behind the fact that, in ordinary life, we can be said to
perceive an object by perceiving some proper part of it? Well, we think of the part we
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perceive as being publicly perceivable; otherwise it would not be part of an object, and so
perceiving it could not count as perceiving a part of an object, and hence could not count
as perceiving an object by virtue of perceiving a proper part of it. But—or so I have
argued--for Berkeley the basic constituents of objects, ideas, are not publicly perceivable.
So, they cannot be parts of an object. Pappas explicitly acknowledges this latter point:
“the ideas in the collection [that constitutes an object] are not parts of the object [italics
in the original].”viii But if ideas are not parts of the object, then we cannot legitimately use
perceiving an object by perceiving a proper part of it as a model for perceiving the object
by perceiving ideas. We cannot say that in perceiving an idea, we perceive a part of the
object, and therefore cannot say that we then perceive the object by perceiving a part of
it. Perhaps this is why Pappas switches to the example of perceiving a troop by
perceiving some members of it. But this does not help: we think of a member of a
troop—a soldier--as a publicly perceivable being; otherwise he or she could not be a
member of the troop. So perceiving something that is not publicly perceivable is not
perceiving a member of the troop; and therefore does not qualify as perceiving the troop
by perceiving a member of it, anymore that perceiving something that is not publicly
perceivable counts as perceiving an object by perceiving a proper part of it.
My point can be made more directly, quite apart from the analogies that Pappas
ues. For I don’t think that Berkeley regards ideas literally as either parts of objects or
“members” of objects. Rather, he regards them as instantiated sensible qualities or tropes,
and he regards them as constituents of an object by virtue of their belonging to a
collection of instantiated qualities or tropes that constitute that object. But again, we think
of an instantiated quality of an object, such as the instance of rectangularity possessed by
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this page, as being publicly perceivable; otherwise it could not be the quality of an object.
So even if we think that we can perceive an object by perceiving some of its sensible
qualities, perceiving ideas will not count as perceiving any instantiated sensible quality of
an object, and therefore will not count as perceiving an object by perceiving some of its
sensible qualities.
In the same vein as Pappas, Robert McKim (who unlike Pappas concedes that
Berkeley is committed the no-shared-ideas principle) claims that Berkeleian objects can
be publicly perceivable even if their constituents are not. He writes:
Berkeley has no difficulty reconciling private ideas and public objects. He
agrees with the commonsense view that we perceive a common or public
world, though his analysis of why this is so is very different from that of
commonsense. If your sensations when you perceive [a] tree and my
sensations when I perceive [a] tree are part of the same family [of
sensations], then we both perceive the same tree …. If a physical object is
understood to consist, at least in part, of a family of sensations which
includes some of your sensations and some of mine, there is no difficulty
for the claim that you and I perceive the same object.ix
This account faces the same difficulty as Pappas’s. Suppose that I now perceive some
sensations that, due to some relations of resemblance or correspondence they bear to
sensations that you perceive, may be called members of the same family of sensations as
the ones you perceive. McKim wants us to agree with him that perceiving these
sensations constitutes us both perceiving the same object. But by what right? For
perceiving such sensations to count as perceiving an object, the sensations in question
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must themselves have objective status: they must be parts of the object, or members of a
group of items that each have objective status, or tropes that have objective status. But
the sensations we perceive, being private to each of us, cannot be parts or members or
tropes with objective status. So, perceiving them cannot count as perceiving an object.
McKim’s assertion that it does is a mere stipulation that does not “analyze”
commonsense, but goes directly against it,
To return to the numbered propositions in the argument stated above, I do not
think that Pappas has shown that (4) (“If no constituent element of an object can be
perceived by two or more minds, then no object can be perceived by two or more
different minds”) is not a necessary truth. For, in the examples that he gives, the
antecedent of (4) is not satisfied: the constituents of an object, whether they be the parts
of it or members of an assemblage that constitute an object in some other (nonmereological) way, must be publicly observable. So when we perceive some necessarily
private item, we cannot correctly say that we perceive an object by perceiving some
constituent of it. Thus my contention that (4) is a necessary truth resists Pappas’s putative
counterexamples, and I conclude that if (as I have argued) Berkeley is committed to
saying that the constituents of objects are not publicly perceivable, then he cannot escape
the consequence that objects are not publicly perceivable.
If there is any sense in which, for Berkeley, we inhabit a common world, then it is
that a single God imprints upon us private ideas between which he institutes certain
relations of correspondence, resemblance, or the like, much as in Leibniz’s theory of preestablished harmony between the perceptions of “windowless” monads. In virtue of these
relations, certain groups of ideas can, from God’s point of view, be called “objects.” But
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it remains that no finite mind has any greater access to the ideas imprinted by God on
another finite mind than I have, say, to your after-images or your aches and pains. Even if
one accepts Berkeley’s theism, this does not come close to what we ordinarily think of as
inhabiting a common world, and if one does not accept his theism, then one is left with
no common world even in his attenuated sense.
5. Philonous’s attack on the no-shared-ideas principle
In light of the foregoing, it seems that the only way Berkeley could show that his
idealism accommodates the commonsense belief in the public perceivability of objects is
to refute the no-shared-ideas principle. My discussion above gives cause for pessimism
about the prospects of refuting that principle. But in the continuation of the passage from
the Third Dialogue that I quoted at the beginning, Philonous attempts to do so. The
purpose of this concluding section is to examine that attempt.
Here again is the opening exchange, followed now by its lengthy continuation:
HYLAS: Is it not your opinion that by our senses we perceive only the
ideas existing in our minds?
PHILONOUS: It is.
HYLAS: But the same idea which is in my mind, cannot be in yours, or in
any other mind. Doth it not therefore follow from your principles, that no
two can see the same thing? And is not this highly absurd?
PHILONOUS: If the term same be taken in the vulgar acceptation, it is
certain (and not at all repugnant to the principles I maintain) that different
persons may perceive the same thing; or the same thing or idea exist in
different minds. Words are of arbitrary imposition; and since men are used
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to apply the word same where no distinction or variety is perceived, and I
do not pretend to alter their perceptions, it follows, that as men have said
before [i.e. before they realized that bodies are only ideas], several saw the
same thing, so they may upon like occasions still continue to use the same
phrase, without any deviation either from propriety of language, or the
truth of things. But if the term same be used in the acceptation of
philosophers, who pretend to an abstracted notion of identity, then,
according to their sundry definitions of this notion (for it is not yet agreed
wherein that philosophic identity consists), it may or may not be possible
for divers persons to perceive the same thing. But whether philosophers
shall think fit to call a thing the same or no, is, I conceive, of small
importance. Let us suppose several men together, all endued with the same
faculties, and consequently affected in like sort by their senses, and who
had yet never known the use of language; they would without question
agree in their perceptions. Though perhaps, when they came to the use of
speech, some regarding the uniformness of what was perceived, might call
it the same thing: others especially regarding the diversity of persons who
perceived, might choose the denomination of different things. But who
sees not that all the dispute is about a word? to wit, whether what is
perceived by different persons, may yet have the term same applied to it?
Or suppose a house, whose walls or outward shell remaining unaltered, the
chambers are all pulled down, and new ones built in their place; and that
you should call this the same, and I should say it was not the same house:
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would we not for all this perfectly agree in our thoughts of the house,
considered in it self? And would not all the difference consist in a sound?
If you should say, we differed in our notions; for that you superadded to
your idea of the house the simple abstracted idea of identity, whereas I did
not; I would tell you I know not what you mean by that abstracted idea of
identity; and should desire you look into your own thoughts, and be sure
you understood yourself--Why so silent, Hylas? Are you not yet satisfied,
men may dispute about identity and diversity, without any real difference
in their thoughts and opinions, abstracted from names? (3D3 W2: 247248)
I shall not attempt to untangle all of the issues that this passage raises, but only to extract
and evaluate its chief line of argument. First we should ask a preliminary question: is the
passage intended to show that two or more people can perceive the same object despite the
fact that they cannot perceive the same ideas, or is it intended to show that two or more
people can perceive the same idea (and therefore also the same object)? The words “same
thing,” the cognate expression “thing the same,” and the antonym “different things” occur
altogether eight times in the passage, but the word “same idea” occurs only once and the
expression “same thing or idea” occurs once. So, it might seem that Philonous’s purpose is
to show that two people can perceive the same object (”thing”) even if they can never
perceive the same idea. Nevertheless, I shall formulate the argument as an attack on the noshared-ideas principle, for two reasons. First, so far as I know, Berkeley nowhere shows
any inclination to argue, à la Pappas and McKim, that objects might be publicly perceivable
even if ideas are private; rather he seems to assume that if ideas are private, then so are
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objects, and to have never even considered the possibility that objects might be publicly
perceivable even if ideas are private. Second, Philonous’s use of the expression “same thing
or idea” in the topic sentence of his reply to Hylas is significant: he means to show that,
contra Hylas’s assertion that “the same idea which is in my mind, cannot be in yours, or in
any other mind,” it is “certain” that the “the same thing or idea [may] exist in different
minds,” where the “or” does not signify disjunction, but rather is a way of saying that
whether one is referring to a “thing” or to an idea makes no difference: both a “thing” and
an idea may, Philonous wants to maintain, exist in different minds.
In accordance with this preliminary point, I offer the following reconstruction of
Philonous’s argument.
(1) If “same” is taken in the ordinary sense, then it is perfectly correct to
say that two or more persons can perceive the same idea.
(2) If “same” is not taken in the ordinary sense, then the question of
whether two or more persons can perceive the same idea has no correct
answer.
(3) Either “same” is taken in the ordinary sense or “same” is not taken in
the ordinary sense.
(4) Either it is perfectly correct to say that two or more persons can
perceive the same idea or the question of whether two or more persons can
perceive the same idea has no correct answer. [from (1)-(3)]
(5) If the question of whether two or more persons can perceive the same
idea has a correct answer, then it is perfectly correct to say that two or
more persons can perceive the same idea. [from (4)]
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(6) The question of whether two or more persons can perceive the same
idea has a correct answer.
(7) It is perfectly correct to say that two or more persons can perceive the
same idea. [from (5) and (6)]
The important premises of this argument are the first two. To justify premise (1), Philonous
points out that on the common use (“vulgar acceptation”) of the term “same,” people apply
this term so long as no difference (“distinction or variety”) is perceived between things, or,
as he says lower, in virtue of “the uniformness of what [is] perceived.” In other words,
people say that X is the “same” as Y provided that they perceive no difference between X
and Y. Therefore, Philonous is arguing, we can say that an idea, I1, in my mind is the
“same” as an idea, 12, in your mind, without violating the common use of language. We
can do this, provided only that no “distinction or variety” is perceived between I1 and 12.
And this condition will often be satisfied, because we are “endued with the same faculties,
and consequently affected in like sort by [our] senses.”
To justify premise (2), Philonous argues that if anyone proposes to use the term
“same” in some way other than this common one, then despite what philosophers may say,
there is really no right answer to the question whether I1 is the “same” as I2. The question
is a purely verbal one; any answer to it is arbitrary; we can say what we like. For, as the
example of the house whose walls remain but whose rooms are changed is supposed to
show, we really have no clear concept of identity applicable to sensible objects other than
the common or “vulgar” one just described.
I shall now argue that this attempt to establish (7) (and thus to deny the no-sharedideas principle) is mistaken. It is true that when we perceive no difference between X and
20
Y, we may say that X is “the same” as Y. For example, if we see no difference between two
left-hand gloves of the same shape, size, color, texture, and workmanship, we may say of
one glove that it is “the same glove” as the other. But let’s not forget the distinction
between qualitative identity and numerical identity. When we say that one glove is the same
as another, we obviously do not mean that that glove is the same one as the other, but only
that it is the same as the other—that it is just like the other. We are not saying that one
glove is numerically identical with the other; we are only saying that one glove is
qualitatively the same as the other, i.e. that it has the same characteristics or qualities (of
shape, size, color, texture, and workmanship) as the other.
The bearing of this distinction on Philonous’s argument is this. The fact that there
may be no discernible difference between an idea or sensation in my mind and one in your
mind means only that they may be qualitatively the same; it does not mean that they are
numerically the same. But their being qualitatively the same in no way supports (7),
because (7) means that it is perfectly correct to say that two or more persons can perceive
numerically the same idea. By the same token, the fact that there may be no discernible
difference between an idea or sensation in my mind and one in your mind in no way goes
against the no-shared-ideas principle, because that principle clearly means that no two or
more persons can perceive numerically the same idea or sensation. (Notice, incidentally,
that Philonous may be trying to exploit the point that no difference could be perceived
between our ideas because no one can perceive both of them--a point which contradicts the
very claim he is defending, viz, that two people could perceive the same idea!)
Does Berkeley have a reply to this objection? Yes, he does, and that reply is
contained in premise (2). For the point of that premise is to block the appeal to the
21
distinction between qualitative sameness and numerical sameness, by claiming, in effect,
that with respect to sensible things, the only kind of sameness that exists is qualitative
sameness. To support this, Philonous appeals to his example of the house whose walls have
been left intact but all of whose rooms have been replaced.
But what does that example really show? It may show that there are cases where
there is no correct answer to the question of whether X is numerically the same as Y; let us
suppose that it does show that. But this does not prove we have no concept of numerical
identity applicable to sensible things.x It shows only that this concept, like many others,
does not come with rules or criteria for its application that cover all possible cases. Some
concepts do come with such rules, e.g. the concept of an even number. We know exactly to
which numbers that concept applies, and to which it does not. But consider the concept of
baldness. Presumably, a man who has only a single hair on his head is still bald. But do we
know exactly how much hair he must have in order not to be bald, or where baldness leaves
off and non-baldness begins? Of course not. There are cases where there is no right answer
to the question whether a person is bald, or to the question of when a person first became
bald. Yet, it does not follow that we have no useable concept of baldness, or that it is
always arbitrary whether we say that someone is bald or not bald, so that we can say
whatever we like. Some people, e.g. Joe Biden, are clearly not bald; others, e.g. Dick
Cheney, clearly are bald. Now all that Philonous’s remarks about the house show is that the
concept of numerical identity may work in the same way as that of baldness. There may be
cases where there is no right answer to the question of whether X is numerically identical
with Y, just as there are cases where there is no right answer to the question of whether a
person is bald. It does not follow from this that we have no concept of numerical identity
22
applicable to sensible things, or that questions concerning the numerical identity of sensible
things are always arbitrary or undecidable.
Here is a concise way of putting my criticism. Premise (1) is true provided that
“same” means “qualitatively the same.” In other words, (1) is true if it means:
(1a) If “same” means “qualitatively the same,” then it is perfectly correct
to say that two or more persons can perceive the same idea.
But if we paraphrase (1) as (1a), then we must paraphrase (2) as
(2a) If “same” does not mean “qualitatively the same,” then the question
of whether two or more persons can perceive the same idea has no correct
answer.
But while (1a) seems perfectly acceptable, there is no reason at all to accept (2a). Hence,
the view that there is a sense of “same” where it means “numerically the same,” and that in
that sense, no two people can perceive the same idea, remains untouched by Philonous’s
arguments. I conclude that Berkeley has not succeeded in refuting the no-shared-ideas
principle. Therefore, it appears that he cannot avoid the consequence that the constituent
elements of objects, and therefore those objects themselves, are not publicly perceivable.
Georges Dicker
The College at Brockport,
State University of New York
23
Notes
In Philonous’s long speech immediately following the above exchange, Berkeley tries to
show that the distinction between qualitative and numerical identity does not apply to
sensible things. In the final section of this paper, I argue that Berkeley’s argument for this
claim is unsound.
i
ii
David Berman, George Berkeley: Idealism and the Man (Oxford: Oxford University
Press, 1994), pp. 51-52.
The transitivity argument does not appeal to the denial of blind agency, but otherwise
overlaps with Berman’s argument.
iii
iv
I owe this point to Eli Hirsch, whose formulation of it (in correspondence) I here quote
almost verbatim.
v
I owe this point to Gordon Barnes, whose formulation of it (in correspondence) I here
quote almost verbatim.
vi
Although this is not essential to my argument, I would go further and hold that the notion
of existence outside of time is unintelligible überhaupt. Abstract entities like numbers may
be said to exist “timelessly,” but that only means that (assuming they exist at all) it makes
no sense to say that they had a beginning in time or will have an end in time; rather, if they
exist at all, then they exist eternally, throughout all time.
vii
George S. Pappas, Berkeley’s Thought (Ithaca: Cornell University Press, 2000), pp. 201202. I do not think that the qualification “immediately” plays any important role in this
argument. See also George S. Pappas, “Berkeley, Perception, and Common Sense,” in
Colin M. Turbayne (ed.), Berkeley: Critical and Interpretive Essays (Minneapolis:
University of Minnesota Press, 1982), 3-21, pp. 9-10 and George S. Pappas, “Berkeley and
Common Sense Realism,” History of Philosophy Quarterly 8:1 (January, 1991), 27-42, p.
37.
viii
Pappas, Berkeley’s Thought, p. 198.
ix
Robert McKim, “Berkeley on Private Ideas and Public Objects,” p. 229-230. In Phillip D.
Cummins and Guenter Zoeller (eds.), Minds, Ideas, and Objects: Essays on the Theory of
Representation in Modern Philosophy (Atascadero: Ridgeview Publishing Company:
1992), 215-233.
The qualification “applicable to sensible things” is needed here, because Berkeley would
not say that we lack a concept of numerical identity applicable to minds.
x