Books: The Principles of Philosophy
R >>
Rene Descartes >> The Principles of Philosophy
Pages:
1 |
2 |
3 |
4 | 5 |
6 |
7
LXXI. That the chief cause of our errors is to be found in the
prejudices of our childhood.
And here we may notice the first and chief cause of our errors. In
early life the mind was so closely bound to the body that it
attended to nothing beyond the thoughts by which it perceived the
objects that made impression on the body; nor as yet did it refer
these thoughts to anything existing beyond itself, but simply felt
pain when the body was hurt, or pleasure when anything beneficial to
the body occurred, or if the body was so highly affected that it was
neither greatly benefited nor hurt, the mind experienced the
sensations we call tastes, smells, sounds, heat, cold, light,
colours, and the like, which in truth are representative of nothing
existing out of our mind, and which vary according to the
diversities of the parts and modes in which the body is affected.
[Footnote: "which vary according to the diversities of the movements
that pass from all parts of our body to the part of the brain to
which it (the mind) is closely joined and united."--FRENCH.] The
mind at the same time also perceived magnitudes, figures, motions,
and the like, which were not presented to it as sensations but as
things or the modes of things existing, or at least capable of
existing out of thought, although it did not yet observe this
difference between these two kinds of perceptions. And afterwards
when the machine of the body, which has been so fabricated by nature
that it can of its own inherent power move itself in various ways,
by turning itself at random on every side, followed after what was
useful and avoided what was detrimental; the mind, which was closely
connected with it, reflecting on the objects it pursued or avoided,
remarked, for the first time, that they existed out of itself, and
not only attributed to them magnitudes, figures, motions, and the
like, which it apprehended either as things or as the modes of
things, but, in addition, attributed to them tastes, odours, and the
other ideas of that sort, the sensations of which were caused by
itself; [Footnote: "which it perceived on occasion of them" (i.e.,
of external objects).--FRENCH.] and as it only considered other
objects in so far as they were useful to the body, in which it was
immersed, it judged that there was greater or less reality in each
object, according as the impressions it caused on the body were more
or less powerful. Hence arose the belief that there was more
substance or body in rocks and metals than in air or water, because
the mind perceived in them more hardness and weight. Moreover, the
air was thought to be merely nothing so long as we experienced no
agitation of it by the wind, or did not feel it hot or cold. And
because the stars gave hardly more light than the slender flames of
candles, we supposed that each star was but of this size. Again,
since the mind did not observe that the earth moved on its axis, or
that its superficies was curved like that of a globe, it was on that
account more ready to judge the earth immovable and its surface
flat. And our mind has been imbued from our infancy with a thousand
other prejudices of the same sort which afterwards in our youth we
forgot we had accepted without sufficient examination, and admitted
as possessed of the highest truth and clearness, as if they had been
known by means of our senses, or implanted in us by nature.
LXXII. That the second cause of our errors is that we cannot forget
these prejudices.
And although now in our mature years, when the mind, being no longer
wholly subject to the body, is not in the habit of referring all
things to it, but also seeks to discover the truth of things
considered in themselves, we observe the falsehood of a great many
of the judgments we had before formed; yet we experience a
difficulty in expunging them from our memory, and, so long as they
remain there, they give rise to various errors. Thus, for example,
since from our earliest years we imagined the stars to be of very
small size, we find it highly difficult to rid ourselves of this
imagination, although assured by plain astronomical reasons that
they are of the greatest,--so prevailing is the power of
preconceived opinion.
LXXIII. The third cause is, that we become fatigued by attending to
those objects which are not present to the senses; and that we are
thus accustomed to judge of these not from present perception but
from pre-conceived opinion.
Besides, our mind cannot attend to any object without at length
experiencing some pain and fatigue; and of all objects it has the
greatest difficulty in attending to those which are present neither
to the senses nor to the imagination: whether for the reason that
this is natural to it from its union with the body, or because in
our early years, being occupied merely with perceptions and
imaginations, it has become more familiar with, and acquired greater
facility in thinking in those modes than in any other. Hence it also
happens that many are unable to conceive any substance except what
is imaginable and corporeal, and even sensible. For they are
ignorant of the circumstance, that those objects alone are
imaginable which consist in extension, motion, and figure, while
there are many others besides these that are intelligible; and they
persuade themselves that nothing can subsist but body, and, finally,
that there is no body which is not sensible. And since in truth we
perceive no object such as it is by sense alone [but only by our
reason exercised upon sensible objects], as will hereafter be
clearly shown, it thus happens that the majority during life
perceive nothing unless in a confused way.
LXXIV. The fourth source of our errors is, that we attach our
thoughts to words which do not express them with accuracy.
Finally, since for the use of speech we attach all our conceptions
to words by which to express them, and commit to memory our thoughts
in connection with these terms, and as we afterwards find it more
easy to recall the words than the things signified by them, we can
scarcely conceive anything with such distinctness as to separate
entirely what we conceive from the words that were selected to
express it. On this account the majority attend to words rather than
to things; and thus very frequently assent to terms without
attaching to them any meaning, either because they think they once
understood them, or imagine they received them from others by whom
they were correctly understood. This, however, is not the place to
treat of this matter in detail, seeing the nature of the human body
has not yet been expounded, nor the existence even of body
established; enough, nevertheless, appears to have been said to
enable one to distinguish such of our conceptions as are clear and
distinct from those that are obscure and confused.
LXXV. Summary of what must be observed in order to philosophize
correctly.
Wherefore if we would philosophize in earnest, and give ourselves to
the search after all the truths we are capable of knowing, we must,
in the first place, lay aside our prejudices; in other words, we
must take care scrupulously to withhold our assent from the opinions
we have formerly admitted, until upon new examination we discover
that they are true. We must, in the next place, make an orderly
review of the notions we have in our minds, and hold as true all and
only those which we will clearly and distinctly apprehend. In this
way we will observe, first of all, that we exist in so far as it is
our nature to think, and at the same time that there is a God upon
whom we depend; and after considering his attributes we will be able
to investigate the truth of all other things, since God is the cause
of them. Besides the notions we have of God and of our mind, we will
likewise find that we possess the knowledge of many propositions
which are eternally true, as, for example, that nothing cannot be
the cause of anything, etc. We will farther discover in our minds
the knowledge of a corporeal or extended nature that may be moved,
divided, etc., and also of certain sensations that affect us, as of
pain, colours, tastes, etc., although we do not yet know the cause
of our being so affected; and, comparing what we have now learne'd,
by examining those things in their order, with our former confused
knowledge of them, we will acquire the habit of forming clear and
distinct conceptions of all the objects we are capable of knowing.
In these few precepts seem to me to be comprised the most general
and important principles of human knowledge.
LXXVI. That we ought to prefer the Divine authority to our
perception; [Footnote: "reasonings."--FRENCH]. but that, apart from
things revealed, we ought to assent to nothing that we do not
clearly apprehend.
Above all, we must impress on our memory the infallible rule, that
what God has revealed is incomparably more certain than anything
else; and that, we ought to submit our belief to the Divine
authority rather than to our own judgment, even although perhaps the
light of reason should, with the greatest clearness and evidence,
appear to suggest to us something contrary to what is revealed. But
in things regarding which there is no revelation, it is by no means
consistent with the character of a philosopher to accept as true
what he has not ascertained to be such, and to trust more to the
senses, in other words, to the inconsiderate judgments of childhood
than to the dictates of mature reason.
PART II.
OF THE PRINCIPLES OF MATERIAL THINGS.
I. The grounds on which the existence of material things may be
known with certainty.
Although we are all sufficiently persuaded of the existence of
material things, yet, since this was before called in question by
us, and since we reckoned the persuasion of their existence as among
the prejudices of our childhood, it is now necessary for us to
investigate the grounds on which this truth may be known with
certainty. In the first place, then, it cannot be doubted that every
perception we have comes to us from some object different from our
mind; for it is not in our power to cause ourselves to experience
one perception rather than another, the perception being entirely
dependent on the object which affects our senses. It may, indeed, be
matter of inquiry whether that object be God, or something different
from God; but because we perceive, or rather, stimulated by sense,
clearly and distinctly apprehend, certain matter extended in length,
breadth, and thickness, the various parts of which have different
figures and motions, and give rise to the sensation we have of
colours, smells, pain, etc., God would, without question, deserve to
be regarded as a deceiver, if he directly and of himself presented
to our mind the idea of this extended matter, or merely caused it to
be presented to us by some object which possessed neither extension,
figure, nor motion. For we clearly conceive this matter as entirely
distinct from God, and from ourselves, or our mind; and appear even
clearly to discern that the idea of it is formed in us on occasion
of objects existing out of our minds, to which it is in every
respect similar. But since God cannot deceive us, for this is
repugnant to his nature, as has been already remarked, we must
unhesitatingly conclude that there exists a certain object extended
in length, breadth, and thickness, and possessing all those
properties which we clearly apprehend to belong to what is extended.
And this extended substance is what we call body or matter.
II. How we likewise know that the human body is closely connected
with the mind.
We ought also to conclude that a certain body is more closely united
to our mind than any other, because we clearly observe that pain and
other sensations affect us without our foreseeing them; and these,
the mind is conscious, do not arise from itself alone, nor pertain
to it, in so far as it is a thing which thinks, but only in so far
as it is united to another thing extended and movable, which is
called the human body. But this is not the place to treat in detail
of this matter.
III. That the perceptions of the senses do not teach us what is in
reality in things, but what is beneficial of hurtful to the
composite whole of mind and body.
It will be sufficient to remark that the perceptions of the senses
are merely to be referred to this intimate union of the human body
and mind, and that they usually make us aware of what, in external
objects, may be useful or adverse to this union, but do not present
to us these objects as they are in themselves, unless occasionally
and by accident. For, after this observation, we will without
difficulty lay aside the prejudices of the senses, and will have
recourse to our understanding alone on this question by reflecting
carefully on the ideas implanted in it by nature.
IV. That the nature of body consists not in weight hardness, colour
and the like, but in extension alone.
In this way we will discern that the nature of matter or body,
considered in general, does not consist in its being hard, or
ponderous, or coloured, or that which affects our senses in any
other way, but simply in its being a substance extended in length,
breadth, and depth. For with respect to hardness, we know nothing of
it by sense farther than that the parts of hard bodies resist the
motion of our hands on coming into contact with them; but if every
time our hands moved towards any part, all the bodies in that place
receded as quickly as our hands approached, we should never feel
hardness; and yet we have no reason to believe that bodies which
might thus recede would on this account lose that which makes them
bodies. The nature of body does not, therefore, consist in hardness.
In the same way, it may be shown that weight, colour, and all the
other qualities of this sort, which are perceived in corporeal
matter, may be taken from it, itself meanwhile remaining entire: it
thus follows that the nature of body depends on none of these.
V. That the truth regarding the nature of body is obscured by the
opinions respecting rarefaction and a vacuum with which we are pre-
occupied.
There still remain two causes to prevent its being fully admitted
that the true nature of body consists in extension alone. The first
is the prevalent opinion, that most bodies admit of being so
rarefied and condensed that, when rarefied, they have greater
extension than when condensed; and some even have subtilized to such
a degree as to make a distinction between the substance of body and
its quantity, and between quantity itself and extension. The second
cause is this, that where we conceive only extension in length,
breadth, and depth, we are not in the habit of saying that body is
there, but only space and further void space, which the generality
believe to be a mere negation.
VI. In what way rarefaction takes place.
But with regard to rarefaction and condensation, whoever gives his
attention to his own thoughts, and admits nothing of which he is not
clearly conscious, will not suppose that there is anything in those
processes further than a change of figure in the body rarefied or
condensed: so that, in other words, rare bodies are those between
the parts of which there are numerous distances filled with other
bodies; and dense bodies, on the other hand, those whose parts
approaching each other, either diminish these distances or take them
wholly away, in the latter of which cases the body is rendered
absolutely dense. The body, however, when condensed, has not,
therefore, less extension than when the parts embrace a greater
space, owing to their removal from each other, and their dispersion
into branches. For we ought not to attribute to it the extension of
the pores or distances which its parts do not occupy when it is
rarefied, but to the other bodies that fill these interstices; just
as when we see a sponge full of water or any other liquid, we do not
suppose that each part of the sponge has on this account greater
extension than when compressed and dry, but only that its pores are
wider, and therefore that the body is diffused over a larger space.
VII. That rarefaction cannot be intelligibly explained unless in
the way here proposed.
And indeed I am unable to discover the force of the reasons which
have induced some to say that rarefaction is the result of the
augmentation of the quantity of body, rather than to explain it on
the principle exemplified in the case of a sponge. For although when
air or water is rarefied we do not see any of the pores that are
rendered large, or the new body that is added to occupy them, it is
yet less agreeable to reason to suppose something that is
unintelligible for the purpose of giving a verbal and merely
apparent explanation of the rarefaction of bodies, than to conclude,
because of their rarefaction, that there are pores or distances
between the parts which are increased in size, and filled with some
new body. Nor ought we to refrain from assenting to this
explanation, because we perceive this new body by none of our
senses, for there is no reason which obliges us to believe that we
should perceive by our senses all the bodies in existence. And we
see that it is very easy to explain rarefaction in this manner, but
impossible in any other; for, in fine, there would be, as appears to
me, a manifest contradiction in supposing that any body was
increased by a quantity or extension which it had not before,
without the addition to it of a new extended substance, in other
words, of another body, because it is impossible to conceive any
addition of extension or quantity to a thing without supposing the
addition of a substance having quantity or extension, as will more
clearly appear from what follows.
VIII. That quantity and number differ only in thought (RATIONE)
from that which has quantity and is numbered.
For quantity differs from extended substance, and number from what
is numbered, not in reality but merely in our thought; so that, for
example, we may consider the whole nature of a corporeal substance
which is comprised in a space of ten feet, although we do not attend
to this measure of ten feet, for the obvious reason that the thing
conceived is of the same nature in any part of that space as in the
whole; and, on the other hand, we can conceive the number ten, as
also a continuous quantity of ten feet, without thinking of this
determinate substance, because the concept of the number ten is
manifestly the same whether we consider a number of ten feet or ten
of anything else; and we can conceive a continuous quantity of ten
feet without thinking of this or that determinate substance,
although we cannot conceive it without some extended substance of
which it is the quantity. It is in reality, however, impossible that
any, even the least part, of such quantity or extension, can be
taken away, without the retrenchment at the same time of as much of
the substance, nor, on the other hand, can we lessen the substance,
without at the same time taking as much from the quantity or
extension.
IX. That corporeal substance, when distinguished from its quantity,
is confusedly conceived as something incorporeal.
Although perhaps some express themselves otherwise on this matter, I
am nevertheless convinced that they do not think differently from
what I have now said: for when they distinguish (corporeal)
substance from extension or quantity, they either mean nothing by
the word (corporeal) substance, or they form in their minds merely a
confused idea of incorporeal substance, which they falsely attribute
to corporeal, and leave to extension the true idea of this corporeal
substance; which extension they call an accident, but with such
impropriety as to make it easy to discover that their words are not
in harmony with their thoughts.
X. What space or internal place is.
Space or internal place, and the corporeal substance which is
comprised in it, are not different in reality, but merely in the
mode in which they are wont to be conceived by us. For, in truth,
the same extension in length, breadth, and depth, which constitutes
space, constitutes body; and the difference between them lies only
in this, that in body we consider extension as particular, and
conceive it to change with the body; whereas in space we attribute
to extension a generic unity, so that after taking from a certain
space the body which occupied it, we do not suppose that we have at
the same time removed the extension of the space, because it appears
to us that the same extension remains there so long as it is of the
same magnitude and figure, and preserves the same situation in
respect to certain bodies around it, by means of which we determine
this space.
XI. How space is not in reality different from corporeal substance.
And indeed it will be easy to discern that it is the same extension
which constitutes the nature of body as of space, and that these two
things are mutually diverse only as the nature of the genus and
species differs from that of the individual, provided we reflect on
the idea we have of any body, taking a stone for example, and reject
all that is not essential to the nature of body. In the first place,
then, hardness may be rejected, because if the stone were liquefied
or reduced to powder, it would no longer possess hardness, and yet
would not cease to be a body; colour also may be thrown out of
account, because we have frequently seen stones so transparent as to
have no colour; again, we may reject weight, because we have the
case of fire, which, though very light, is still a body; and,
finally, we may reject cold, heat, and all the other qualities of
this sort, either because they are not considered as in the stone,
or because, with the change of these qualities, the stone is not
supposed to have lost the nature of body. After this examination we
will find that nothing remains in the idea of body, except that it
is something extended in length, breadth, and depth; and this
something is comprised in our idea of space, not only of that which
is full of body, but even of what is called void space.
XII. How space differs from body in our mode of conceiving it.
There is, however, some difference between them in the mode of
conception; for if we remove a stone from the space or place in
which it was, we conceive that its extension also is taken away,
because we regard this as particular, and inseparable from the stone
itself: but meanwhile we suppose that the same extension of place in
which this stone was remains, although the place of the stone be
occupied by wood, water, air, or by any other body, or be even
supposed vacant, because we now consider extension in general, and
think that the same is common to stones, wood, water, air, and other
bodies, and even to a vacuum itself, if there is any such thing,
provided it be of the same magnitude and figure as before, and
preserve the same situation among the external bodies which
determine this space.
XIII. What external place is.
The reason of which is, that the words place and space signify
nothing really different from body which is said to be in place, but
merely designate its magnitude, figure, and situation among other
bodies. For it is necessary, in order to determine this situation,
to regard certain other bodies which we consider as immovable; and,
according as we look to different bodies, we may see that the same
thing at the same time does and does not change place. For example,
when a vessel is being carried out to sea, a person sitting at the
stern may be said to remain always in one place, if we look to the
parts of the vessel, since with respect to these he preserves the
same situation; and on the other hand, if regard be had to the
neighbouring shores, the same person will seem to be perpetually
changing place, seeing he is constantly receding from one shore and
approaching another. And besides, if we suppose that the earth
moves, and that it makes precisely as much way from west to east as
the vessel from east to west, we will again say that the person at
the stern does not change his place, because this place will be
determined by certain immovable points which we imagine to be in the
heavens. But if at length we are persuaded that there are no points
really immovable in the universe, as will hereafter be shown to be
probable, we will thence conclude that nothing has a permanent place
unless in so far as it is fixed by our thought.
XIV. Wherein place and space differ.
The terms place and space, however, differ in signification, because
place more expressly designates situation than magnitude or figure,
while, on the other hand, we think of the latter when we speak of
space. For we frequently say that a thing succeeds to the place of
another, although it be not exactly of the same magnitude or figure;
but we do not therefore admit that it occupies the same space as the
other; and when the situation is changed we say that the place also
is changed, although there are the same magnitude and figure as
before: so that when we say that a thing is in a particular place,
we mean merely that it is situated in a determinate way in respect
of certain other objects; and when we add that it occupies such a
space or place, we understand besides that it is of such determinate
magnitude and figure as exactly to fill this space.
Pages:
1 |
2 |
3 |
4 | 5 |
6 |
7