1. Introduction
Hume distinguishes, though somewhat informally, between the human being
and the human person. The human being is composed for him of both the body and the mind,
whereas the human person is the same as the self, the mind, or the soul. While the body
may be viewed as something relatively static, the human person or mind is for him
something essentially dynamic, an ongoing process. After pointing out that we do not have
any idea of "the self" or person since we do not have any "particular
impression" of the self that would correspond to the "idea" of self and
thus it would be its "copy," Hume declares in a famous passage:
For my part, when I enter most intimately into what I call myself,
I always stumble on some particular perception or other, of heat or cold, light of shade,
love or hatred, pain or pleasure. I never can catch myself at any time without a
perception, and never can observe anything but perception...setting aside some
metaphysicians...,I may venture to affirm of the rest of mankind, that they are 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 Treatise,I,IV,6).
The exact meaning of this passage, i.e., Hume’s view of the
ontology of personhood, is somewhat problematic. It would seem, at first sight, that Hume
understands personhood in mentalistic and, by implication, dualistic terms. For he is
describing the self or person here, and in many other passages, as the sum total of
perceptions, emotions, and sensations — as something made up of these mentalistic
contents. At the same time, he asserts that these contents "are in a perpetual flux
and movement," which would be a false assertion if that "flux" is
constantly interrupted for long periods by sleep, and the physicalistic interpretation
would be the correct one. We begin by examining the mentalistic interpretation.
2. The Mentalistic View of Personhood
In describing the human self or person, Hume routinely uses a dual
terminology. He speaks of the self, the mind, the soul, or the person as an agent or an
author of manifold cognitive and emotive acts, while, at the same time, in other numerous
passages, he explicitly treats the self as nothing more than the sum total of these same
activities interrelated among themselves in many complex ways but remaining independent of
the dualistic substantial self and its alleged authorship. This conflicting terminology is
no doubt due to the fact that Hume, by his own admission, feels necessitated to employ
mentalistic terms to describe physical data — the brain processes. But this poses a
serious problem for him. Having rejected the Cartesian concept of the soul as a mental
substance as well as the agent or author of mental acts, he is forced to leave mental
acts, i.e., ideas, impressions, perceptions, suspended, so to speak, in the air as acts
without an agent.
No matter how serious at the first sight, this difficulty, arising from
his dual terminology, need not perhaps be fatal to his conception of the self as the sum
total, "a bundle or collection of different perceptions." Whenever he is using
expressions suggestive of a mental agent such as "mind," "soul," or
"self," he can perhaps be always interpreted as accommodating himself to the
popular linguistic usage.
The really serious difficulties arise when we undertake to examine the
components themselves that make up the human self or person according to Hume, i.e., his
"ideas" and "impressions." These components prove themselves to be
problematic to the degree where we may justly wonder whether the Humean self is a
logically viable entity.
To begin with, "ideas" are said to "resemble"
"impressions" from which they are supposed to arise, to be "copies" of
impressions, to be pretty much the same as impressions, only less vivacious, less
forceful. If we now inquire into how we discover these crucial differences between ideas
and impressions, we find that Hume proposes introspection as the method of this discovery.
In a word, we are invited to "observe" our "ideas" and compare them
with their corresponding "impressions" and to see for ourselves that impressions
are almost always more vivid and forceful than their corresponding ideas. The basic
difficulty with this introspective method is that, in order to discover whether ideas
indeed "resemble" impressions, are "copies" of them, and are less
vivid than they, the impressions, we should be able to compare the two among themselves by
means of a perception, which, by definition, can come only after the first two, the
impression and the idea, have occurred. But such a comparison is plainly impossible
because by the time we have formed that third comparing perception or idea, the impression
from which the idea to be compared arose has ceased to exist, leaving that idea by itself
with nothing to compare. Should we, however, suppose that the impression continues to
exist along with the idea, then the two, the impression and the idea, would after all be
only one entity and the comparison, which, by definition, presupposes here two entities
would be out of the question. If, however, we attempted to compare the idea with its
impression before this impression has ceased to exist, we would have only that impression
alone but no idea yet. In either case, the alleged or recommended comparison would be a
sheer impossibility.
Another serious difficulty concerns the concept of
"resemblance" itself as employed by Hume. "Resemblance," you see, is
ordinarily used to compare colors, shapes, sounds, or tastes of some external objects with
those of other external objects, but not with those of ideas. We are probably joking when
we say that ideas smell, taste, or have a color. For instance, we may call a painting or a
photo a "copy" or "resemblance" of some particular landscape or maybe
of another painting, but we are using the terms "copy" or
"resemblance" purely metaphorically when we apply them to the ideas or
impressions of these objects. Hume seems to confuse the merely metaphorical resemblance
with the real one, which alone is required here. When he claims that ideas
"resemble" their impressions, he is speaking metaphorically. But he is also
speaking metaphorically when he claims that impressions resemble external objects.
Impressions may indeed resemble other impressions as regards their strength or their
constituent qualities just as apples may resemble other apples. But to assert that
impressions resemble external objects makes just as little sense as to claim that, as a
saying goes, apples resemble oranges. The comparison is purely metaphorical. Again,
although "resemblance" might make some sense when applied to visual phenomena
since we can perhaps meaningfully speak of "images" of visual things, it loses
any meaning when we try to apply it to smells, tastes, touches, or sounds.
"Resemblance" comes, after all, from "idea," i.e., "eidos"
or "image" of visible things. So while an idea may perhaps be said, at least
according to Hume, to resemble its visual impression, to be an "image" of it, it
hardly makes any sense to speak of an "image," "eidos," or
"idea" of the taste, smell, touch, or sound impressions, and still less sense to
speak of these impressions as "resemblances" or "images" of external
objects as their alleged causes.
The final difficulty with the distinction, so crucial for Hume’s
epistemology and metaphysics, between impressions and ideas consists in the fact that, as
he himself recognizes, ideas can sometimes be more vivid and forceful than impressions.
But if in some cases the higher degree of vividness is not a reliable criterion of
distinction between ideas and impressions, why is it to be considered as reliable in all
others? To suggest that a greater vividness is abnormal for ideas is to beg the question
by assuming that a lesser vividness is normal for them and that the real or imagined
statistical majority is always to be regarded as the criterion of normalcy. Can we not
assume that, in an overwhelming majority of cases, our ideas come in a variety of degrees
of forcefulness and vividness just as in case of impressions, without us being aware when
these ideas are more and when less vivid than their corresponding impressions, especially
since the ideas as memories and their corresponding impressions are often separated by
long intervals of time? The greatest difficulty with the comparison of ideas and
impressions in order to determine their respective vividness is that, as we saw earlier,
no comparison of the two kinds of perceptions is logically possible. For the comparing
perception presupposes that both the idea and the impression are available for comparison,
that they exist at the same time. But, as we saw, only one of them is available at any
given time. Should we say that we can compare an idea with a memory of its impression, we
would be merely comparing two ideas, and not an idea with an impression, since a memory,
for Hume, is an idea.
The above considerations force us to conclude that the constituents
that make up our minds or persons, the "ideas" and "impressions,"
cannot be logically conceived in mentalistic terms. For what Hume calls ideas, may be
nothing else than continuing impressions or continuations of impressions with alternating
degrees of vividness.
3. The Physicalistic View of Personhood
Now since the mentalistic interpretation of Hume’s fundamental
constituents of selfhood or personhood is highly problematic, if not logically impossible,
we should attempt a physicalistic one, especially since these constituents seem to be
eminently susceptible to it. After all, Hume is conceiving the self or person as a dynamic
process rather than as a static agent that occasionally erupts into activities by positing
some thoughts or emotions. Since the preceding analysis of Hume’s
"perceptions" has shown to us that his distinction between
"impressions" and "ideas" is gratuitous, we are going entirely to
dispense with it in this part of our paper.
What Hume treats as an "impression" that allegedly gives
origin to an "idea", its "copy", logically should be treated merely as
the point of inception of the perceptual process of longer or shorter duration, and what
he calls an "idea" should be viewed as nothing more than the
"impression" itself whose external (or internal) stimulus, after producing it,
has ceased to operate. The contemporary research into physico-chemical electrical
processes of neurons makes it at least difficult, if not impossible, to conceive ideas on
the metaphor of a Lockean jar of pickles or even on that of a Cartesian agent with ideas
as it products.
If we are to use any metaphor at all, it should be one that denotes a
dynamic process. We should compare ideas and impressions to the sound waves arising, for
instance, from a piano when one of its keys is struck or from a bell, and spreading
perhaps long distances before gradually subsiding completely at the end. In this way,
ideas would not be viewed as "copies" of impressions. They would be viewed
— and correctly — as these impressions themselves, i.e., as continuations of
these impressions minus the stimuli that gave rise to them. What Hume calls
"ideas," these entities dangling in the air detached from their moorings, their
"impressions", "would be viewed as relatively stable systems of electrical
intra-neuronal and inter-neuronal currents that function as indispensable parts or factors
within the physico-chemical processes of individual neurons and of their specialized
clusters. Individual neurons and their specialized functional clusters, the
"seats" of "perceptions," could also be compared to boiling cauldrons,
each containing within itself a large system of smaller "pots" each of them
filled with a variety of chemicals interacting with each other in countless ways. Every
new electrical wave viewed by Hume as an "idea" or a cluster of new waves or
"ideas" would be incorporated more or less successfully into this highly complex
and dynamic system for longer or shorter periods of time in direct proportion to the
strength of the original stimuli as well as of additional reinforcements.
We see at once the crucial role which the strength or weakness of the
original stimuli and their subsequent reinforcements plays in determining the duration of
the individual components of the perceptual system, when we consider that out of
thousands, maybe millions of all kinds and "sizes" of perceptions that we may
have in the course of one single day we are hardly able to remember a few dozens or at
most hundreds. And if we go back years or decades in our lives, the number of our memories
or "ideas" eventually may shrink to a zero. What is happening to all other
countless billions of our memories or "ideas?" The same thing which happens to
sounds of bells and movements of hurricanes: they cease to exist. Also the brain capacity
to absorb and to retain new contents or incorporate new processes, like that of any other
organ in its functions, is strictly limited. It may be like the capacity of a container
filled to the brim: new liquid can perhaps be forced into it only by dislodging some of
the old one.
It would seem then that the life expectancy of neuronal processes,
i.e., "ideas" or memories, is in direct proportion to the brain’s being a
"blank tablet" in early years or to the force of some particular experiences or
"impressions," or stimuli in later years, or to both factors combined. The less
the neurons or their clusters are cluttered up with large numbers of electrical currents
and chemical processes of often trivial consequence, the easier it must be for a few major
currents to establish themselves, to get "rooted" more permanently.
The difficulty facing our conception of "ideas" on the
metaphor of vibrating chords or ringing bells, i.e., as processes, is that, while an
interruption of the vibrating chord brings to an end that process, the process called
"idea" seems to be capable of numerous interruptions without being brought to an
end. Maybe "ideas" are after all somewhat like pickles that can be lifted out of
a jar and dropped back into it as often as we please without any change in their life
expectancy. This difficulty can be easily answered by pointing out that available evidence
strongly suggests that physiological processes called "ideas" are incapable of
an interruption, that they merely alternate between being peripheral or unperceived, or
"unconscious" in mentalistic terminology, and emerging into the primary focus as
"memories" from among numerous other perhaps momentarily less forceful
competitors — past and present "perceptions." It seems quite obvious that
it is the survival needs of an organism that determine which neuronal processes or
"memories" are going to move into focus and at what frequency rate while the
rest, the overwhelming majority of them, are doomed to faster or slower decay on the
periphery.
Should someone dispute our contention that "ideas" or
neuronal currents are "incapable of an interruption" by pointing out that sleep
notoriously interrupts them regularly, we could validly argue that it is precisely the REM
stages of sleep — that is, if such stages as described exist at all — that
prove, at least in part, the continuity of our "ideas" as dreams. Our critic
could further urge that deep sleep dreamless stages certainly prove that "ideas"
conceived as dreams or neuronal processes cease to exist during these stages, and that,
therefore, after we wake up we should have no "ideas" or memories of what has
preceded our sleep. And since this is notoriously not the case, are we not entitled, our
critic might ask, to assume that we are closer to truth when we compare "ideas"
to pickles rather than to processes. After all, we can repeatedly pick them up while they
remain the same or maybe leave at least a certain sediment which helps our memories to
arise after we wake up, or our dreams to occur when we reach the REM stage.
Our answer to this potentially fatal objection would be that the rapid
eye movements of the REM stages do not prove at all, that, while we are in this stage, we
are actually dreaming, if dreams can be explained, as they certainly can and as some
researchers are presently doing, as pseudo-memories, or clusters of them, that occur at
those times or in those persons in which the physiological closure between sleeping and
waking is maybe too slow or otherwise imperfect, i.e., when being only partially awake, we
are actually "spinning" our dreams while at the same time unconsciously
imagining and believing that we are remembering them. This theory would also explain why,
upon being awakened from a deep sleep stage, the subjects cannot report any dreams. For
even during the REM stage rapid eye movements are, as we just saw, no reliable proof of
dreaming during that stage since they can plausibly be interpreted as a part of many other
signs or symptoms, commonly observed, of general restlessness before an organism’s
gradual awaking. We must conclude perhaps that apparently no presently known criteria, not
even the dreamer’s own memory, prove beyond a doubt that any dreams at all occur
during sleep at any of its stages. This obviously does not mean that dreams do not occur
during all stages of sleep — only that their occurrence during any stage cannot be
reliably proven. But it certainly can and must be postulated as highly plausible, i.e., it
must be assumed as real since otherwise we would not be able to interpret
"ideas," memories etc. as continuing processes each with a life expectancy of
its own, and would be forced to fall back on the self-contradictory mentalistic
interpretation.
Should we, however, accept the above physicalistic interpretation of
"ideas", memories, and dreams, many puzzling "psychological" phenomena
would stop being puzzling. The regular or "normal" phenomena of schizophrenia,
"multiple" personality, somnambulism, hallucination, and religious visions of
the saints, not to mention occasional occurrence of dreams parallel with or within the
normal waking consciousness, would turn out to be, on a closer examination, just so many
different forms, or perhaps degrees, of dreaming.
But if dreaming is an ongoing process both in sleep and at least
sometimes in waking state, that is, if dreaming and waking can sometimes coexist, how does
the dream differ from waking consciousness? Apparently the dreaming as a neuronal process
does not stop just because another neural process triggered by a new set of stimuli,
called waking consciousness comes onto the scene. The dreaming process only becomes
unconscious, with the waking consciousness dislodging the dreaming consciousness from the
primary focus, in other words, depriving dreaming, either entirely or at least in part, of
its own consciousness. The waking consciousness is capable of doing this simply because,
being a "bundle" or a system of reactions to external stimuli of various kinds,
it is more powerful than the dream system that consists of only decaying perceptions or
long past reactions to the stimuli, which, like so many echoes, are slowly vanishing into
distance. We may add that by consciousness we do not mean "the second order"
thoughts supervening upon "the first order" thoughts, as some mentalists
contend. Consciousness is apparently nothing else than perception or the neuronal process
itself insofar as it, at some points of its duration, due to its interaction with other
processes, happens to acquire more strength than at other points.
The constraints of time do not permit us to analyze much of Hume’s
mentalistically conceived philosophy in physicalistic terms. A couple of examples will
suffice. Hume’s theory of thinking as association of ideas possessing a merely
self-contradictory "reality" would have to be conceived in terms of complex
neuronal processes interacting with each other according to certain quite predictable
patterns determined by the stimuli operating over longer or shorter periods of time.
Hume’s theory of causality as association of ideas in terms of the priority in time
as well as the constant conjunction could be interpeted in terms of the association of
neuronal processes. Two neuronal processes that have occurred in constant conjunction a
certain number of times could be supposed to have established some sort of affinity, even
a kind of unity, so that when, in the future, one process occurs the other one is
triggered so the two occur as inseparable parts of one and the same process. The same
principle of constant conjunction of neuronal process could be used to interpret in
physicalistic terms also other parts of Hume’s philosophy such as his theory of
truth, both conceptual and factual, his theory of morality, and perhaps even that of
religion.
4. Conclusion
The preceding considerations make it plausible that, since the
mentalistic interpretation of the Humean selfhood or personhood runs us into unsolvable
difficulties, the physicalistic interpretation is the correct one and even in harmony with
Hume’s thought. They strongly suggest that, from the ontological point of view, the
human person is essentially the sum total of neuronal processes that occur as reactions,
immediate or remote, to stimuli. These reactions can be viewed either as haphazard or,
perhaps more correctly, as constituting some form of system. One of the advantages of this
view of personhood is that it provides to human beings solid moorings within the realm of
biology rather than leaving them suspended in the realm of mythology. It provides a firm
basis for animals’ rights advocates: non-human animals must or at least can be viewed
as possessing rights since they are persons. For their selves or persons are made up of
the same neuronal processes, instead of being mere "machines," as Descartes
imagined. However, these remarks do not intend in the least to dismiss the "realm of
mythology" as worthless. Human beings might very well possess spiritual souls as
claimed by Descartes and a long tradition. Only we have no evidence, at least no rational
evidence, to support our belief in such souls.
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