It is well known that David Hume rejected any idea of a 'substance of the mind' that
would account for, among other things, personal identity. I will attempt to show that
Hume's argument against the existence of substantival mind presupposes that such an entity
actually exists, and that therefore his argument can be interpreted as an indirect
proof for the existence of substantival mind; that is, as a reductio ad absurdum
of his own position. To demonstrate this, I will give first a brief rehearsal of
Hume’s epistemology in general, then as it is applied specifically to the mind.
Hume’s Epistemology
The great project of Empiricism, in its incipience, was to discover, in Locke's words,
"...the original, certainty, and extent of human knowledge..." (1)
In his Treatise of Human Nature, Hume is intent upon developing a "science of
Man" (2) which would acquaint us with "the extent
and force of human understanding, and [which] could explain the nature of the ideas we
employ, and of the operations we perform in our reasonings." (3)
Hume hoped that this 'Science of Man' would serve as a solid foundation for all other
sciences, both natural and philosophical, and that it would ultimately eradicate
conflicting theories in all fields by defining the limits of human knowledge.
For Hume, all knowledge originates with experience, and all experience is of one’s
own perceptions. We have direct knowledge only of perceptions, not of what the
perceptions are of (if, indeed, they may be counted as of anything); for the
perception stands between the perceiving mind and its supposed real-world object. Hume
says,
...'tis impossible for us so much as to conceive or form an idea of any thing
specifically different from [our perceptions]. Let us fix our attention out of ourselves
as much as possible: Let us chase our imaginations to the heavens, or to the utmost limits
of the universe; we never really advance a step beyond ourselves, nor can conceive any
kind of existence, but those perceptions, which have appeared in that narrow compass. (4)
Hume recognizes two kinds of perceptions: impressions and ideas. The
distinguishing factor between these is simply the degree of "force and liveliness
with which they strike upon the mind". (5) Impressions
enter the mind with "force and violence", while ideas are but the "faint
images" of these which occur in thought and reasoning. (6)
Further, all perceptions, both impressions and ideas, can be either simple or complex.
Simple perceptions are "such as admit of no distinction nor separation", while
complex perceptions "are contrary to these and may be distinguished into parts".
(7) Hume observes that, while all of his simple ideas have
exactly corresponding impressions, many of his complex ideas do not; and that,
furthermore, many of his complex impressions are not represented exactly with complex
ideas. He gives the example of his idea of the New Jerusalem from the New Testament book
of Revelation, with its streets of gold and walls made of gems — a complex idea for
which he has no exactly corresponding complex impression; and conversely, his idea of
Paris, which though indeed complex does not exactly represent his impression of that city.
(8) Upon this note Hume establishes the principle "That
all our simple ideas in their first appearance are derived from simple impressions, which
are correspondent to them, and which they exactly represent." (9)
But this is not true for complex ideas, for some are 'non-corresponding'. This treatment
of perceptions allows for a very 'reasonable' scepticism toward the existence of those
things supposed to be represented by non-corresponding complex ideas.
Of course, applied rigorously Hume’s system can substantiate neither a firm denial
nor an affirmation of the existence of these things — it is an epistemology, not an
ontology. However, the tendency, not only of Hume himself, but of those who have since
accepted his work, has been to act as though this epistemology had genuine
ontological implications. It is only in assuming that the would-be objects of
non-corresponding complex ideas positively do not exist that it becomes necessary to
propose an explanation for the existence of those ideas. That is, if Hume did not grant
his epistemology ontological consequence, there would be no need to progress beyond
scepticism. That he feels the need to offer an explanation for the existence of these
non-corresponding complex ideas belies the fact that he from the beginning assumes the
possibility that they do not originate in the 'external world'. Thus, out of the
scepticism emerges the now familiar scheme of psychological manufacture. The imagination,
Hume claims, combines otherwise legitimate simple ideas, creating from them complex ideas
of whatever form it likes; thus generating, by these fabricative acts, the 'objects' of
our illusory experience. But, it seems unlikely that such random fabrications of the
imagination should follow so regular a pattern that they could become the objects of our
seemingly well-ordered experience. Hume insists, therefore, that there must be some
'principles of association' which guide the imagination’s activities in this vein. He
says,
Were ideas entirely loose and unconnected, chance alone would join them; and
'tis impossible that the same simple ideas should fall regularly into complex
ones...without some bond of union among them. (10)
This bond of union, these principles of association, Hume decides, are three:
Resemblance, Spatial and Temporal Contiguity, and Cause-Effect. Resemblance is easily
understood. Impressions may share common properties. This results in resemblance not only
between the impressions themselves, but between the ideas which correspond to those
impressions. This resemblance then facilitates the conveyance of the mind from one idea to
another. Spatial and Temporal Contiguity are likewise fairly straightforward. Hume
explains that the senses must take their objects as they are found, contiguous to one
another; and that the imagination "must by long custom acquire the same manner of
thinking". (11)
Hume encounters a problem in the relation of cause and effect. Causation is the
only one of the three principles of association which might allow an inference to
something beyond sensory data. Hume, though, denies this possibility, saying:
There is nothing in any objects to persuade us, that they are either always
remote or always contiguous; and when from experience and observation we discover, that
their relation in this particular is invariable, we always conclude that there is some
secret cause, which unites or separates them. (12)
There is no rational justification for belief in causation, for there is no
"impression which produces an idea of such prodigious consequence." (13)
Ultimately, causation is reduced to, in Hume’s words, "constant
conjunction" — the presence of impressions which, by chance, always go together.
(14)
Hume’s Treatment of Mind
But what is this imagining and associating element which Hume blames for the
manufacture of our notion of causation and of other 'non-corresponding' complex ideas?
Usually, such activities would be explained in terms of the faculties of a mind; but Hume
does not allow for such an entity. According to Hume, the mind belongs alongside the ideas
it purportedly creates, in the realm of fiction. He challenges:
I desire those philosophers, who pretend that we have an idea of the substance
of our minds, to point out the impression that produces it, and tell distinctly after what
manner that impression operates, and from what object it is derived. (15)
Again we enter the arena of epistemological deconstruction, only this time with the
mind as our 'object'. The process is the same as with cause and effect: we have no
simple idea of the mind, nor of the substance of the mind — all we have are the
simple impressions and ideas of sensations. Each of these impressions and ideas are
distinct, thus separable, from any others, including the fictitious idea of mind. Hume
says:
since all our perceptions are different from each other, and from everything
else in the universe, they are also distinct and separable, and may be considered as
separately existent, and may exist separately, and have no need of anything else to
support their existence. (16)
Not only is there no idea of mind as a substance, but neither is there any need for it,
since perceptions can exist in themselves. Granting this epistemological paradigm
ontological consequence, as Hume seems to do, all that is left of 'the mind' are these
individual perceptions. The result is the well-known 'bundle theory' of personal identity.
In Hume's own words, a person may be regarded as "nothing but a bundle or collection
of different perceptions, which succeed each other with an inconceivable rapidity, and are
in a perpetual flux and movement". (17)
Hume realises that this account of the mind (and, really, of the person) creates a
special problem for our idea of personal identity. Whence comes the notion that a stream
of independent perceptions forms one enduring entity? Really, this question is applicable
to all experience. If, as Hume seems to say, experience consists in distinct and separable
simple perceptions, how can any fictitious complex idea be formed, whether of the self or
of an other? To construct such a fiction will require more than the imagination. If
there is never more than one simple perception present at a time, the imagination will
need to make use of perceptions not currently present in order to form complex fictions.
That is, it will have to somehow remember past perceptions in order to combine them with
whatever perception is now present. But remembering is not a power proper to the
imagination — it is a faculty unto itself. Recognising this, Hume invokes what seems
to be a distinct faculty: the memory. Hume says:
As the memory alone acquaints us with the continuance and extent of this
succession of perceptions, 'tis to be considered, upon that account chiefly, as the source
of personal identity. Had we no memory, we should never have any notion of causation, nor
consequently of that chain of causes and effects which constitute our self or person. But
having once acquired this notion of causation from the memory, we can extend the same
chain of causes, and consequently the identity of our persons, beyond our memory, and can
comprehend times and circumstances and actions which we have entirely forgot, but suppose
in general to have existed. (18)
The latter part of this statement — i.e., the extending and the comprehending
— seems to refer the action of the imagination. The fabrication of complex fictions,
therefore, involves the interaction of the imagination and the memory.
That is Hume’s epistemology. In a nutshell: many of the notions of things which we
often take to be given in our experience, e.g., substance, personal identity, and other
causal relations, are fictions which the imagination and memory are jointly encouraged to
produce in reaction to three phenomena among impressions: resemblance, spatial and
temporal contiguity, and constant conjunction. Because things appear
to be similar, seem to be uninterrupted, and are usually found in the same combinations
and orders, "we often feign some new and unintelligible principle that connects
objects together, and prevents their interruption and variation". (19)
The Need for Something Beyond
Having run quickly through the complexities of the Humean epistemology, I will now
discuss some issues which stand open to criticism. First, it is clear that the whole
scheme of psychological fabrication requires an agent. Hume attempts to provide an agent
in the form of the 'faculties' of imagination, memory, and so-forth. Moreover, though, it
is apparent that this agent must be enduring and unified. This is simply to say that there
must be something which is capable of being aware of, being influenced by, and acting upon
the principles of association; and those principles seem to be such that only a continuing
observer could be made aware of them, and that only a unified observer could be moved to
use them to construct fictions in the way Hume describes.
First, the agent must endure through time. Hume seems to recognise this when he insists
that the imagination "must by long custom acquire the same manner of
thinking", (20) i.e., in order for the imagination to
create a fiction, it must have repeated experiences of objects which resemble, are
contiguous, and are constantly conjoined. But in order to have repeated experiences it
would seem that the agent must endure through time. Moreover, it is precisely Hume's
recognition of this need that occasions his invocation of memory in his discussion of
personal identity. Memory, he says, acquaints us with the continuance of the stream
of perceptions. In order to do this, it would seem that the memory itself must continue
right along with that stream while in some sense standing apart from it. Second, because
there are multiple faculties involved in the process of fabrication (imagination and
memory), there must be some principle of unity which joins them together; for the
imagination and the memory must somehow form a unit so that the imagination has unhindered
access to the repository of simple ideas in the memory, and the memory in turn must have
uninterrupted access to the fabrications of the imagination. In the end, however, the
system does not allow for a continuing, unified observer. All that it allows are distinct
and separable simple perceptions which exist independently.
Of course, it seems that Hume intends that the faculties should somehow solve these
problems, though it is unlikely that he really meant these to form an enduring, unified
agent. But, if he did not, they do not solve the problems. We may ask where, in this world
of separate atomic structures, are the faculties to be located? Normally we would think of
faculties as faculties of a mind, or perhaps of a person; but these are not real things
for Hume. They are fictions. The mind and the person fade away into a series, or a
collection of perceptions; and there is no place amidst these perceptions for the
inherence of enduring faculties such as imagination or memory. The mind itself, being only
a moment-by-moment succession of individual impressions, seems incapable of doing the sort
of remembering and associating necessary to make any use of Resemblance, Contiguity, or
Constant Conjunction.
The faculties, whatever they are, are not constituents of the Humean mind, for they are
neither ideas nor impressions. Or are they? What nature does Hume mean to give the
faculties by introducing them into his system? Does he mean to treat them as
'things-in-themselves', or only as perceptions, possibly of things? On the one
hand, it seems that the most one might claim within the limits of Humean epistemology are
impressions or ideas of these faculties, or perhaps of the acts of these faculties. But
perceptions of the faculties will not create the enduring, unified agent Hume needs. A
fleeting perception, or a series of them, simply does not seem to be the sort of thing
which could acquire a habit, or custom; but there is nothing else present to do so. Also,
we must ask whether our ideas of these are simple or complex, and whether they have
corresponding impressions or not. If they are complex and 'non-corresponding', can they
possibly avoid sharing the fate of the ideas of mind, and of cause and effect,
viz., epistemological deconstruction? And if they are of the 'corresponding' variety,
simple or complex, they still fail to provide a unified agent; for one cannot provide
unity among a set of distinct and separable perceptions simply by adding more distinct and
separable perceptions. Our perceptions of memory and imagination — and these
seems to be all that Hume’s epistemology will allow — , therefore contribute
nothing to a solution of this problem.
On the other hand, neither will venturing beyond the limits of this epistemology (as
Hume seems to do) to invoke these faculties in themselves grant a solution. When
Hume invokes memory to account for unity among the perceptions, he comes close to begging
the question, for it seems he must assume the existence of some unknown unifying principle
among the faculties themselves, which enables the memory, as one of those faculties, to
explain the unity of the perceptions. Ultimately, he succeeds only in removing the problem
of unity one step, from the perceptions to the faculties.
In the end, there seems to be no category within the limits of the Humean epistemology
to which these faculties might belong and, at the same time, do the work Hume needs
them to do. As perceptions, they fail to provide an adequate agent, while, as
'things-in-themselves' they not only violate the limits of Hume’s own epistemology,
but result in a question-begging, ad hoc type of solution; which is, of course, no
solution at all. Humean Empiricism, therefore, requires something beyond mere sense
experiences (perceptions) which is capable of unifying experience —
something to which perceptions might in some way belong. At the very least, it
requires something which enables a consistent explanation of the 'common-sense' or
'naïve' view of experience, even if that view be delusion; but the Humean view is
incapable of providing it. In order to account for this 'common-sense' view, Hume must
subtly invoke the enduring, unified faculties of imagination and memory, which are, on his
own account, faculties of nothing — not of a mind, certainly not of
perceptions.
The whole of Hume’s 'delusional epistemology' requires the existence of and
knowledge of an enduring, unified agent with faculties of imagination and memory,
yet his metaphysical schema does not explain how this entity is either ontologically
possible or epistemologically admissible. In fact, it strongly suggests that such an
entity is neither. This, I believe, poses a serious problem for Humean Empiricism, for it
cannot, on its own grounds, account for the elements which alone would make it possible.
By attempting to reduce experience to 'sense perception', Empiricism eliminates the
elements which make sense perception possible. One historian of philosophy has noted,
The attempt to by-pass or exclude metaphysics will often be found to involve a
concealed metaphysical assumption, an unavowed theory of being. In other words, the theory
that scientific advance pushes metaphysics out of the picture is mistaken. Metaphysics
simply reappears in the form of concealed assumptions. (21)
Hume’s 'concealed assumption', his 'unavowed theory of being', is precisely the
existence of some supposed entity, in the midst of the stream of perceptions which
otherwise constitute the 'person-as-bundle', with faculties of imagination and of memory,
which persists through time and change, and is thus able to recognise the relations of
Resemblance, Contiguity, and Constant Conjunction and employ them to develop customs, or
habits, and, in turn, to form fictitious complex ideas. This complex, unified something
which persists through time and change certainly seems to be a lot like a substantival
mind. Thus, it is not unfair to say that the existence of substantival mind is a hidden
premise in Hume’s argument.
Now, if Hume’s denial of substantival mind really does rest on the assumption of
its existence, then the structure of his argument is, roughly speaking, more an example of
indirect proof, or reductio ad absurdum, than of direct proof. Indirect
proof is a hypothetical inference rule whereby, if, given hypothesis p, one can
derive a contradiction (p & not-p), one may validly infer not-p.
Hume’s denial of mind rests upon the work of the supposed faculties of memory and
imagination, which seem to indicate the existence of a mind. Thus, in the present case,
given Hume’s hypothesis that mind does not exist (not-m), along with its
attendant assumptions, we are able to derive a contradiction (m & not-m), and
may therefore dispense with the hypothesis and conclude not-not-m, or simply m,
mind exists. If this is so, Hume’s work, regardless of his intentions, might be
properly considered evidence more in support of substantival mind than against it.
In any case, since the assumption of this mind-like entity is involved in every act of
experience, whether delusional or not, its existence and its nature deeply affect every
aspect of Hume’s system. Any weakness or uncertainty in Hume’s doctrine of mind
will carry significant implications for the whole of his project. By drawing attention to
the difficulties surrounding Hume’s treatment of mind, I hope to have shown that a
dark cloud hovers over the whole of his system.
|
