the+critique+of+pure+reason_纯粹理性批判-第119部分
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side of his triangle; thus forming two adjacent angles which are
together equal to two right angles。 He then divides the exterior of
these angles; by drawing a line parallel with the opposite side of the
triangle; and immediately perceives that be has thus got an exterior
adjacent angle which is equal to the interior。 Proceeding in this way;
through a chain of inferences; and always on the ground of
intuition; he arrives at a clear and universally valid solution of the
question。
But mathematics does not confine itself to the construction of
quantities (quanta); as in the case of geometry; it occupies itself
with pure quantity also (quantitas); as in the case of algebra;
where plete abstraction is made of the properties of the object
indicated by the conception of quantity。 In algebra; a certain
method of notation by signs is adopted; and these indicate the
different possible constructions of quantities; the extraction of
roots; and so on。 After having thus denoted the general conception
of quantities; according to their different relations; the different
operations by which quantity or number is increased or diminished
are presented in intuition in accordance with general rules。 Thus;
when one quantity is to be divided by another; the signs which
denote both are placed in the form peculiar to the operation of
division; and thus algebra; by means of a symbolical construction of
quantity; just as geometry; with its ostensive or geometrical
construction (a construction of the objects themselves); arrives at
results which discursive cognition cannot hope to reach by the aid
of mere conceptions。
Now; what is the cause of this difference in the fortune of the
philosopher and the mathematician; the former of whom follows the path
of conceptions; while the latter pursues that of intuitions; which
he represents; a priori; in correspondence with his conceptions? The
cause is evident from what has been already demonstrated in the
introduction to this Critique。 We do not; in the present case; want to
discover analytical propositions; which may be produced merely by
analysing our conceptions… for in this the philosopher would have
the advantage over his rival; we aim at the discovery of synthetical
propositions… such synthetical propositions; moreover; as can be
cognized a priori。 I must not confine myself to that which I
actually cogitate in my conception of a triangle; for this is
nothing more than the mere definition; I must try to go beyond that;
and to arrive at properties which are not contained in; although
they belong to; the conception。 Now; this is impossible; unless I
determine the object present to my mind according to the conditions;
either of empirical; or of pure; intuition。 In the former case; I
should have an empirical proposition (arrived at by actual measurement
of the angles of the triangle); which would possess neither
universality nor necessity; but that would be of no value。 In the
latter; I proceed by geometrical construction; by means of which I
collect; in a pure intuition; just as I would in an empirical
intuition; all the various properties which belong to the schema of
a triangle in general; and consequently to its conception; and thus
construct synthetical propositions which possess the attribute of
universality。
It would be vain to philosophize upon the triangle; that is; to
reflect on it discursively; I should get no further than the
definition with which I had been obliged to set out。 There are
certainly transcendental synthetical propositions which are framed
by means of pure conceptions; and which form the peculiar
distinction of philosophy; but these do not relate to any particular
thing; but to a thing in general; and enounce the conditions under
which the perception of it may bee a part of possible experience。
But the science of mathematics has nothing to do with such
questions; nor with the question of existence in any fashion; it is
concerned merely with the properties of objects in themselves; only in
so far as these are connected with the conception of the objects。
In the above example; we merely attempted to show the great
difference which exists between the discursive employment of reason in
the sphere of conceptions; and its intuitive exercise by means of
the construction of conceptions。 The question naturally arises: What
is the cause which necessitates this twofold exercise of reason; and
how are we to discover whether it is the philosophical or the
mathematical method which reason is pursuing in an argument?
All our knowledge relates; finally; to possible intuitions; for it
is these alone that present objects to the mind。 An a priori or
non…empirical conception contains either a pure intuition… and in this
case it can be constructed; or it contains nothing but the synthesis
of possible intuitions; which are not given a priori。 In this latter
case; it may help us to form synthetical a priori judgements; but only
in the discursive method; by conceptions; not in the intuitive; by
means of the construction of conceptions。
The only a priori intuition is that of the pure form of phenomena…
space and time。 A conception of space and time as quanta may be
presented a priori in intuition; that is; constructed; either alone
with their quality (figure); or as pure quantity (the mere synthesis
of the homogeneous); by means of number。 But the matter of
phenomena; by which things are given in space and time; can be
presented only in perception; a posteriori。 The only conception
which represents a priori this empirical content of phenomena is the
conception of a thing in general; and the a priori synthetical
cognition of this conception can give us nothing more than the rule
for the synthesis of that which may be contained in the
corresponding a posteriori perception; it is utterly inadequate to
present an a priori intuition of the real object; which must
necessarily be empirical。
Synthetical propositions; which relate to things in general; an a
priori intuition of which is impossible; are transcendental。 For
this reason transcendental propositions cannot be framed by means of
the construction of conceptions; they are a priori; and based entirely
on conceptions themselves。 They contain merely the rule; by which we
are to seek in the world of perception or experience the synthetical
unity of that which cannot be intuited a priori。 But they are
inpetent to present any of the conceptions which appear in them
in an a priori intuition; these can be given only a posteriori; in
experience; which; however; is itself possible only through these
synthetical principles。
If we are to form a synthetical judgement regarding a conception; we
must go beyond it; to the intuition in which it is given。 If we keep
to what is contained in the conception; the judgement is merely
analytical… it is merely an explanation of what we have cogitated in
the conception。 But I can pass from the conception to the pure or
empirical intuition which corresponds to it。 I can proceed to
examine my conception in concreto; and to cognize; either a priori
or a posterio; what I find in the object of the conception。 The
former… a priori cognition… is rational…mathematical cognition by
means of the construction of the conception; the latter… a
posteriori cognition… is purely empirical cognition; which does not
possess the attributes of necessity and universality。 Thus I may
analyse the conception I have of gold; but I gain no new information
from this analysis; I merely enumerate the different properties
which I had connected with the notion indicated by the word。 My
knowledge has gained in logical clearness and arrangement; but no
addition has been made to it。 But if I take the matter which is
indicated by this name; and submit it to the examination of my senses;
I am enabled to form several synthetical… although still empirical…
propositions。 The mathematical conception of a triangle I should
construct; that is; present a priori in intuition; and in this way
attain to rational…synthetical cognition。 But when the
transcendental conception of reality; or substance; or power is
presented to my mind; I find that it does not relate to or indicate
either an empirical or pure intuition; but that it indicates merely
the synthesis of empirical intuitions; which cannot of course be given
a priori。 The synthesis in such a conception cannot proceed a
priori… without the aid of experience… to the intuition which
corresponds to the conception; and; for this reason; none of these
conceptions can produce a determinative synthetical proposition;
they can never present more than a principle of the synthesis* of
possible empirical intuitions。 A transcendental proposition is;
therefore; a synthetical cognition of reason by means of pure
conceptions and the discursive method; and it renders possible all
synthetical unity in empirical cognition; though it cannot present
us with any intuition a priori。
*In the case of the conception of cause; I do really go beyond the
empirical conception of an event… but not to the intuition which
presents this conception in concreto; but only to the time…conditions;
which may be found in