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On the
Origin of Our Ideas
by David Hume
All the perceptions of the human mind resolve
themselves into two distinct kinds, which I shall
call impressions and ideas. The
difference betwixt these consists in the degrees of
force and liveliness with which they strike upon
the mind and make their way into our thought or
consciousness. Those perceptions which enter with
most force and violence we may name
impressions; and under this name I
comprehend all our sensations, passions, and
emotions, as they make their first appearance in
the soul. By ideas I mean the faint images
of these in thinking and reasoning; such as, for
instance, are all the perceptions excited by the
present discourse, excepting only those which arise
from the sight and touch, and excepting the
immediate pleasure or uneasiness it may occasion. I
believe it will not be very necessary to employ
many words in explaining this distinction. Every
one of himself will readily perceive the difference
betwixt feeling and thinking. The common degrees of
these are easily distinguished, though it is not
impossible but in particular instances they may
very nearly approach to each other. Thus in sleep,
in a fever, in madness, or in any very violent
emotions of soul, our ideas may approach to our
impressions; as on the other hand it sometimes
happens that our impressions are so faint and low,
that we cannot distinguish them from our ideas. But
notwithstanding this near resemblance in a few
instances, they are in general so very different
that no one can make a scruple to rank them under
distinct heads, and assign to each a peculiar name
to mark the difference.
There is another division of our perceptions
which it will be convenient to observe, and which
extends itself both to our impressions and ideas.
This division is into simple and
complex. Simple perceptions or impressions
and ideas are such as admit of no distinction nor
separation. The complex are the contrary to these,
and may be distinguished into parts. Though a
particular color, taste, and smell are qualities
all united together in this apple, 'tis easy to
perceive they are not the same but are at least
distinguishable from each other.
Having by these divisions given an order and
arrangement to our objects, we may now apply
ourselves to consider with the more accuracy their
qualities and relations. The first circumstance
that strikes my eye is the great resemblance
betwixt our impressions and ideas in every other
particular except their degree of force and
vivacity. The one seem to be in a manner of the
reflection of the other; so that all the
perceptions of the mind are double, and appear both
as impressions and ideas. When I shut my eyes and
think of my chamber, the ideas I form are exact
representations of the impressions I felt; nor is
there any circumstance of the one which is not to
be found in the other. In running over my other
perceptions I find still the same resemblance and
representation. Ideas and impressions appear always
to correspond to each other. This circumstance
seems to me remarkable, and engages my attention
for a moment.
Upon a more accurate survey I find I have been
carried away too far by the first appearance, and
that I must make use of the distinction of
perceptions into simple and complex, to limit this
general decision that all our ideas and
impressions are resembling. I observe that many
of our complex ideas never had impressions that
corresponded to them, and that many of our complex
impressions never are exactly copied in ideas. I
can imagine to myself such a city as the New
Jerusalem, whose pavement is gold and walls are
rubies, though I never saw any such. I have seen
Paris; but shall I affirm I can form such an idea
of that city as will perfectly represent all its
streets and houses in their real and just
proportions?
I perceive, therefore, that though there is in
general a great resemblance betwixt our
complex impressions and ideas, yet the rule
is not universally true that they are exact copies
of each other. We may next consider how the case
stands with our simple perceptions. After
the most accurate examination of which I am
capable, I venture to affirm that the rule here
holds without any exception, and that every simple
idea has a simple impression which resembles it,
and every simple impression a correspondent idea.
That idea of red which we form in the dark and that
impression which strikes our eyes in sunshine
differ only in degree, not in nature. That the case
is the same with all our simple impressions and
ideas 'tis impossible to prove by a particular
enumeration of them. Everyone may satisfy himself
in this point by running over as many as he
pleases. But if anyone should deny this universal
resemblance, I know no way of convincing him but by
desiring him to show a simple impression that has
not a correspondent idea, or a simple idea that has
not a correspondent impression. If he does not
answer this challenge, as 'tis certain he cannot,
we may from his silence and our own observation
establish our conclusion.
Thus we find that all simple ideas and
impressions resemble each other; and as the complex
are formed from them, we may affirm in general that
these two species of perception are exactly
correspondent. Having discovered this relation,
which requires no farther examination, I am curious
to find some other of their qualities. Let us
consider how they stand with regard to their
existence, and which of the impressions and ideas
are causes and which effects.
The full examination of this question is
the subject of the present treatise; and therefore
we shall here content ourselves with establishing
one general proposition, that all our simple
ideas in their first appearance are derived from
simple impressions, which are correspondent to
them, and which they exactly represent.
In seeking for phenomena to prove this
proposition I find only those of two kinds, but in
each kind the phenomena are obvious, numerous, and
conclusive. I first make myself certain, by a new
review, of what I have already asserted, that every
simple impression is attended with a correspondent
idea and every simple idea with a correspondent
impression. From this constant conjunction of
resembling perceptions I immediately conclude that
there is a great connection betwixt our
correspondent impressions and ideas, and that the
existence of the one has a considerable influence
upon that of the other. Such a constant
conjunction, in such an infinite number of
instances, can never arise from chance; but clearly
proves a dependence of the impressions on the
ideas, or of the ideas on the impressions. That I
may know on which side this dependence lies I
consider the order of their first
appearance, and find by constant experience
that the simple impressions always take the
precedence of their correspondent ideas, but never
appear in the contrary order. To give a child an
idea of scarlet or orange, of sweet or bitter, I
present the objects, or in other words, convey to
him these impressions; but proceed not so absurdly
as to endeavor to produce the impressions by
exciting the ideas. Our ideas upon their appearance
produce not their correspondent impressions, nor do
we perceive any color or feel any sensation merely
upon thinking of them. On the other hand we find
that any impression either of the mind or body is
constantly followed by an idea which resembles it
and is only different in the degrees of force and
liveliness. The constant conjunction of our
resembling perceptions is a convincing proof that
the one are the causes of the other; and this
priority of the impression is an equal proof that
our impressions are the causes of our ideas, not
our ideas of our impressions.
To confirm this I consider another plain and
convincing phenomenon; which is, that wherever by
any accident the faculties which give rise to any
impressions are obstructed in their operations, as
when one is born blind or deaf, not only the
impressions are lost but also their correspondent
ideas; so that there never appear in the mind the
least traces of either of them. Nor is this only
true where the organs of sensation are entirely
destroyed, but likewise where they have never been
put in action to produce a particular impression.
We cannot form to ourselves a just idea of the
taste of a pineapple without having actually tasted
it.
There is however one contradictory phenomenon
which may prove that 'tis not absolutely impossible
for ideas to go before their correspondent
impressions. I believe it will readily be allowed
that the several distinct ideas of colors which
enter by the eyes, or those of sounds which are
conveyed by the hearing, are really different from
each other, though at the same time resembling. Now
if this be true of different colors, it must be no
less so of the different shades of the same color,
that each of them produces a distinct idea,
independent of the rest. For if this should be
denied, 'tis possible, by the continual gradation
of shades, to run a color insensibly into what is
most remote from it; and if you will not allow any
of the means to be different, you cannot without
absurdity deny the extremes to be the same. Suppose
therefore a person to have enjoyed his sight for
thirty years, and to have become perfectly well
acquainted with colors of all kinds excepting one
particular shade of blue, for instance, which it
never has been his fortune to meet with. Let all
the different shades of that color, except that
single one, be placed before him, descending
gradually from the deepest to the lightest, 'tis
plain that he will perceive a blank where that
shade is wanting, and will be sensible that there
is a greater distance in that place betwixt the
contiguous colors than in any other. Now I ask
whether 'tis possible for him, from his own
imagination, to supply this deficiency, and raise
up to himself the idea of that particular shade,
though it had never been conveyed to him by his
senses? I believe there are few but will be of
opinion that he can; and this may serve as a proof
that the simple ideas are not always derived from
the correspondent impressions; though the instance
is so particular and singular that 'tis scarce
worth our observing, and does not merit that for it
alone we should alter our general maxim.
But besides this exception, it may be amiss to
remark on this head that the principle of the
priority of impressions to ideas must be understood
with another limitation, viz., that as our
ideas are images of our impressions, so we can form
secondary ideas which are images of the primary; as
appears from this very reasoning concerning them.
This is not, properly speaking, an exception to the
rule so much as an explanation of it. Ideas produce
the images of themselves in new ideas; but as the
first ideas are supposed to be derived from
impressions, it still remains true that all our
simple ideas proceed either mediately or
immediately from their correspondent
impressions.
This then is the first principle I establish in
the science of human nature; nor ought we to
despise it because of the simplicity of its
appearance. For 'tis remarkable that the present
question concerning the precedency of our
impressions or ideas is the same with what has made
so much noise in other terms, when it has been
disputed whether there be any innate ideas,
or whether all ideas be derived from sensation and
reflection. We may observe that in order to prove
the ideas of extension and color not to be innate,
philosophers do nothing but show that they are
conveyed by our senses. To prove the ideas of
passion and desire not to be innate, they observe
that we have a preceding experience of these
emotions in ourselves. Now if we carefully examine
these arguments, we shall find that they prove
nothing but that ideas are preceded by other more
lively perceptions, from which they are derived,
and which they represent. I hope this clear stating
of the question will remove all disputes concerning
it, and will render this principle of more use in
our reasonings that it seems hitherto to have
been.
Excerpted from A Treatise of
Human Nature, by David Hume
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A
Treatise of Human
Nature:
Being
an Attempt to Introduce the Experimental
Method
of
Reasoning into Moral
Subjects,
by
David Hume
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