Treatise 1.4.2
On the causes leading us to believe in the
existence of “body”
(bodies are objects that continue to exist
independently of being perceived)
(Hume considered the question of the
justification for the belief in body to be
beside the point —
— since believing in the existence of
body is not an option for us …
… we are compelled to do so
… and we need to do so)
The causes leading us to believe in the
existence of body
could lead us to believe one or other
(or both)
of two different things:
• that objects continue to exist
when not being perceived
• that objects are distinct from the
mind and its perceptions
meaning:
• that they exist outside of us
• that they exist and act
independently of us
There are three possible causes of the
belief:
• the senses
• reason
• the imagination
Why the belief can’t be based on the
senses
The senses only give us impressions.
And …
… they obviously can’t produce a belief in
continued existence of our impressions
apart from being perceived.
Were they to produce a belief in distinct
existence, they would have to do so by
leading us to believe either:
• that our impressions are images of
distinctly existing objects, or …
• that our impressions just are
distinctly existing objects
They can’t do the first because they give us
no idea of any objects other than our
impressions.
Neither can they do the second.
• because they can’t lead us to think
that our impressions are external to
ourselves
◦ because we have no impression of
self that they could be external to
◦ because our impressions of things
outside our bodies are no different
from our impressions of our bodies
in all being impressions had by the
mind, and so things within the mind
(this is particularly evident of
impressions of sound, taste, and smell,
but recent theories of vision have
recognized that it is even true of those
of vision)
◦ because there is no fallacy in
sensation, which always presents
impressions as being what they are,
…
… and all our impressions
(of primary qualities, of
secondary qualities, and of
pleasures and pains)
originally appear to us as being “on
the same footing”
that is, as all being merely
impressions in us and nothing else
external to us.
• because they can’t lead us to think
that our impressions are
independent of us
◦ since independence has to do with
causes, and causal relations are
only ascertained by the imagination
Why the belief can’t be based on reason
The belief has one or other of two forms:
• that our impressions just are bodies
• that our impressions are subjective
effects and/or representations of
bodies
If the belief has the first form, then there is
no role for reason to play, since there is no
inference from impression to body.
If the belief has the second form, then it is
not accepted by the majority of people, who
believe that all impressions, except for
those of pain and pleasure, exist outside of
themselves.
So the belief must be based on the
imagination.
Moreover, the belief the imagination
produces
must be a belief in the continued or distinct
existence of our very impressions
themselves.
More precisely, it must be a belief in the
continued or distinct existence of some of
our impressions …
(those of sensation excluding pain & pleasure,
visual after-images, etc.)
… but not of others
(passions, pains, visual after-images).
What is the difference between these two
groups of impressions that inspires the
imagination to produce the belief?
– not their superior force or vivacity
– not their occurring independently of the
will
– rather, their constancy and coherence
What is it about their constancy and
coherence that leads the imagination to
form the belief?
1. An inadequate explanation.
We need to suppose that impressions
continue to exist unperceived in order to
preserve our belief in their coherence.
[Some examples to illustrate why we
might think this]
The reason why this explanation is
inadequate:
It doesn’t account for how we
get the belief in coherence in
the first place.
Our belief in the coherence of
certain impressions attributes
more regularity to those
impressions than we discover
by experience.
Consequently, the belief
cannot be grounded on
experience.
2. Something else the belief might be
grounded on:
An inertial tendency of the imagination
Having observed a certain degree of
coherence in objects as they appear
to the senses,
we go on to suppose the
unperceived existence of objects in
order to be able to attribute a yet
greater degree of coherence to them
and so “render the uniformity as
compleat as possible”
The problem with 2
It is too weak to support such a grand
conclusion as the unperceived existence of
all objects.
Hume’s solution
Look for the cause of the belief in the
constancy of the impressions, giving rise to
the belief in their continued existence apart
from being perceived.
How this happens
When the [1] same object (i.e., impression)
is frequently present and absent to the
senses, we are impelled to imagine [2] it to
[3] continue to exist between the
appearances, and [4] believe that this is
really the case.
(Note that the object under consideration
here really is just an impression; not an
object distinct from our impressions.
This is because the belief just is a belief in
the unperceived existence of our
perceptions,
at least in the form in which most of us have
it.)
4 parts of this explanation that need to be
discussed:
1. What we mean by “the same object.”
2. Why we consider two objects interrupted
by a gap to nonetheless be the same.
3. Why we are impelled to form the idea
that the object continues to exist
unperceived across the gap.
4. Why we believe this idea.
1. What we mean by “same”
Hume’s view of time and identity:
Where there is no change there is no
passage of time.
So a view of an unchanging object gives
no idea of the passage of time.
So such a view gives us just a single
impression.
Where there is any change, we receive
multiple impressions.
However, sometimes, while we are having
a single impression, we also have other,
changing impressions.
Comparison of these two impression sets
with one another leads us to imaginatively
split the single impression into earlier and
later appearances.
When we think of the earlier and later
appearances we think there are many
things.
When we think there is really just one
impression we think there is just one
thing.
We run these two thoughts together to
form the (really contradictory) notion of
the oneness of the many things.
This is the idea of identity or sameness of
an object through an interval of time.
(It is really a mish-mash of
inconsistent thoughts.)
2. Why we consider two objects interrupted
by a gap to nonetheless be the same
object.
When one impression ceases, something
else happens, and then another impression
starts, we are undeniably having two
impressions and not one.
But suppose the two impressions very
closely resemble one another.
Then the state the mind feels itself in when
it contemplates them feels to it very much
like the state it is in when it contemplates a
strictly identical object
(when it has a single impression over a
supposed variation of time, with no gaps)
So there are two resemblances:
– between the two separated
impressions
– between the way it feels to
contemplate two separated
impressions and the way it feels to
contemplate an “identical” object
The effect of these resemblances is to lead
us to confuse the two kinds of experience.
As a consequence, we think that in this
case as well we are contemplating just one
object, rather than two.
3. Why we consider the object to exist
unperceived across the gap
Because we realize from just a bit of
reflection that we really are having two
impressions, not one.
But this realization does not eliminate the
influence of the resemblance relations,
which continue to tempt us to think of the
objects as being one.
We try to eliminate the contrary evidence by
inventing the fiction of the existence of the
object when it is not being perceived.
An objection
But isn’t the object we are supposing to
exist unperceived just an impression, and
isn’t it a gross error to suppose that an
impression can exist unperceived?
No. A mind is just a bundle of perceptions,
and there is no contradiction in supposing
one of them to detach itself from the bundle
and return to it later.
On this account, for an object to be
perceived just is for an impression to enter
the bundle.
4. Why we believe the object continues to
exist unperceived.
Because of vivacity transmitted from our
memories of the resembling impressions to
the idea of an unperceived impression
linking them
In this case, the vivacity is
transmitted from the memories by
the “propensity” we have to consider
the memories to be connected by the
existence of something unperceived.
So it is indirectly due to the
resemblance relation, which is the
ground of that propensity.
A problem with this cause of belief in body
The cause leads us to believe in the
continued existence of our impressions.
And thereby their distinct existence
(because continued existence
implies distinct existence and vice
versa)
But we have good reason to suppose that
our impressions have no distinct existence.
An “experiment” to confirm this:
Press the side of an eyeball and you
see everything double.
Consider these doubled images.
Causal reasoning shows that at least
one of them is dependent on
pressing the side of the eyeball.
And so not distinct from us and what
we do to ourselves.
But the two images are alike in all
respects but position.
From like effects we ought to infer
like causes.
So the other image must be due to
us as well.
This same reasoning could be applied to
any of a number of instances of perceptual
relativity and variation.
e.g., the changes in the size and
shape of visible objects with changes
in our position
Upshot
We are caught up in a contradiction:
Imagination,
under the influence of the
resemblance relation and
natural propensities
leads us to believe in the continued
existence of our impressions when
not perceived and hence their
distinct existence.
But causal reasoning leads us to
deny the distinct existence of our
impressions and hence to deny that
they could continue to exist when not
perceived.
What do we do about this?
The vulgar:
– do not think about the problem and
simply continue to follow natural
instinct & imagination
Philosophers
– try to have things both ways:
• satisfy the imagination by
continuing to believe that objects
exist unperceived
• satisfy reason by denying that
these objects are our impressions
This leads to a theory of “double existence”
According to this theory, our impressions
are caused by distinct, external objects that
resemble them.
So our impressions are transient
images or copies of distinct,
continued external objects.
Problems with the vulgar theory
It is patently false.
Problems with the philosophical theory
It makes a causal assertion that is
unjustified and unjustifiable.
Before we can say that x causes y, we
need to have had experience of x’s
regularly being followed by y’s.
But we have no experience of distinct
external objects resembling our
impressions and causing them. We only
ever experience our impressions.
Philosophers invent the theory of double
existence because they wanted to have
things both ways.
(Because the vulgar way of looking
at things still holds enough sway
over them that they want to reconcile
it with reason.)
But because there is no good reason for the
theory, …
… if they believe it,
their belief is based on wishful
thinking (and on the propensities of
the imagination leading us to wish
that way)
not on the evidence.
Hume’s sceptical conclusion
After a thorough review of the causes of the
belief in body,
it is hard not to be sceptical of the
soundness of that belief.
All the same, none of us is capable of
preserving in this scepticism for long and
believing only what is legitimated by
reason.
Our nature forces us to believe in body
whether we think the reasons for doing so
are good or not.