the critique of pure reason-第139章
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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
incompetent 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 experience to correspond to the conception。 My
procedure is; therefore; strictly according to conceptions; I cannot
in a case of this kind employ the construction of conceptions; because
the conception is merely a rule for the synthesis of perceptions;
which are not pure intuitions; and which; therefore; cannot be given a
priori。
There is thus a twofold exercise of reason。 Both modes have the
properties of universality and an a priori origin in common; but
are; in their procedure; of widely different character。 The reason
of this is that in the world of phenomena; in which alone objects
are presented to our minds; there are two main elements… the form of
intuition (space and time); which can be cognized and determined
completely a priori; and the matter or content… that which is
presented in space and time; and which; consequently; contains a
something… an existence corresponding to our powers of sensation。 As
regards the latter; which can never be given in a determinate mode
except by experience; there are no a priori notions which relate to
it; except the undetermined conceptions of the synthesis of possible
sensations; in so far as these belong (in a possible experience) to
the unity of consciousness。 As regards the former; we can determine
our conceptions a priori in intuition; inasmuch as we are ourselves
the creators of the objects of the conceptions in space and time…
these objects being regarded simply as quanta。 In the one case; reason
proceeds according to conceptions and can do nothing more than subject
phenomena to these… which can only be determined empirically; that is;
a posteriori… in conformity; however; with those conceptions as the
rules of all empirical synthesis。 In the other case; reason proceeds
by the construction of conceptions; and; as these conceptions relate
to an a priori intuition; they may be given and determined in pure
intuition a priori; and without the aid of empirical data。 The
examination and consideration of everything that exists in space or
time… whether it is a quantum or not; in how far the particular
something (which fills space or time) is a primary substratum; or a
mere determination of some other existence; whether it relates to
anything else… either as cause or effect; whether its existence is
isolated or in reciprocal connection with and dependence upon
others; the possibility of this existence; its reality and necessity
or opposites… all these form part of the cognition of reason on the
ground of conceptions; and this cognition is termed philosophical。 But
to determine a priori an intuition in space (its figure); to divide
time into periods; or merely to cognize the quantity of an intuition
in space and time; and to determine it by number… all this is an
operation of reason by means of the construction of conceptions; and
is called mathematical。
The success which attends the efforts of reason in the sphere of
mathematics naturally fosters the expectation that the same good
fortune will be its lot; if it applies the mathematical method in
other regions of mental endeavour besides that of quantities。 Its
success is thus great; because it can support all its conceptions by a
priori intuitions and; in this way; make itself a master; as it
were; over nature; while pure philosophy; with its a priori discursive
conceptions; bungles about in the world of nature; and cannot accredit
or show any a priori evidence of the reality of these conceptions。
Masters in the science of mathematics are confident of the success
of this method; indeed; it is a common persuasion that it is capable
of being applied to any subject of human thought。 They have hardly
ever reflected or philosophized on their favourite science… a task
of great difficulty; and the specific difference between the two modes
of employing the faculty of reason has never entered their thoughts。
Rules current in the field of common experience; and which common
sense stamps everywhere with its approval; are regarded by them as
axiomatic。 From what source the conceptions of space and time; with
which (as the only primitive quanta) they have to deal; enter their
minds; is a question which they do not trouble themselves to answer;
and they think it just as unnecessary to examine into the origin of
the pure conceptions of the understanding and the extent of their
validity。 All they have to do with them is to employ them。 In all this
they are perfectly right; if they do not overstep