opinion。 The philosopher abandons them； so soon as the opposite
party renounces its dogmatical conceit。 To maintain a simply
negative position in relation to propositions which rest on an
insecure foundation； well befits the moderation of a true philosopher；
but to uphold the objections urged against an opponent as proofs of
the opposite statement is a proceeding just as unwarrantable and
arrogant as it is to attack the position of a philosopher who advances
affirmative propositions regarding such a subject。
It is evident； therefore； that hypotheses； in the speculative
sphere； are valid； not as independent propositions； but only
relatively to opposite transcendent assumptions。 For； to make the
principles of possible experience conditions of the possibility of
things in general is just as transcendent a procedure as to maintain
the objective reality of ideas which can be applied to no objects
except such as lie without the limits of possible experience。 The
judgements enounced by pure reason must be necessary； or they must not
be enounced at all。 Reason cannot trouble herself with opinions。 But
the hypotheses we have been discussing are merely problematical
judgements； which can neither be confuted nor proved； while；
therefore； they are not personal opinions； they are indispensable as
answers to objections which are liable to be raised。 But we must
take care to confine them to this function； and guard against any
assumption on their part of absolute validity； a proceeding which
would involve reason in inextricable difficulties and contradictions。
SECTION IV。 The Discipline of Pure Reason in Relation
to Proofs。
It is a peculiarity； which distinguishes the proofs of
transcendental synthetical propositions from those of all other a
priori synthetical cognitions； that reason； in the case of the former；
does not apply its conceptions directly to an object； but is first
obliged to prove； a priori； the objective validity of these
conceptions and the possibility of their syntheses。 This is not merely
a prudential rule； it is essential to the very possibility of the
proof of a transcendental proposition。 If I am required to pass； a
priori； beyond the conception of an object； I find that it is
utterly impossible without the guidance of something which is not
contained in the conception。 In mathematics； it is a priori
intuition that guides my synthesis； and； in this case； all our
conclusions may be drawn immediately from pure intuition。 In
transcendental cognition； so long as we are dealing only with
conceptions of the understanding； we are guided by possible
experience。 That is to say； a proof in the sphere of transcendental
cognition does not show that the given conception （that of an event；
for example） leads directly to another conception （that of a cause）…
for this would be a saltus which nothing can justify； but it shows
that experience itself； and consequently the object of experience；
is impossible without the connection indicated by these conceptions。
It follows that such a proof must demonstrate the possibility of
arriving； synthetically and a priori； at a certain knowledge of
things； which was not contained in our conceptions of these things。
Unless we pay particular attention to this requirement； our proofs；
instead of pursuing the straight path indicated by reason； follow
the tortuous road of mere subjective association。 The illusory
conviction； which rests upon subjective causes of association； and
which is considered as resulting from the perception of a real and
objective natural affinity； is always open to doubt and suspicion。 For
this reason； all the attempts which have been made to prove the
principle of sufficient reason； have； according to the universal
admission of philosophers； been quite unsuccessful； and； before the
appearance of transcendental criticism； it was considered better； as
this principle could not be abandoned； to appeal boldly to the
mon sense of mankind （a proceeding which always proves that the
problem； which reason ought to solve； is one in which philosophers
find great difficulties）； rather than attempt to discover new
dogmatical proofs。
But； if the proposition to be proved is a proposition of pure
reason； and if I aim at passing beyond my empirical conceptions by the
aid of mere ideas； it is necessary that the proof should first show
that such a step in synthesis is possible （which it is not）； before it
proceeds to prove the truth of the proposition itself。 The so…called
proof of the simple nature of the soul from the unity of apperception；
is a very plausible one。 But it contains no answer to the objection；
that； as the notion of absolute simplicity is not a conception which
is directly applicable to a perception； but is an idea which must be
inferred… if at all… from observation； it is by no means evident how
the mere fact of consciousness； which is contained in all thought；
although in so far a simple representation； can conduct me to the
consciousness and cognition of a thing which is purely a thinking
substance。 When I represent to my mind the power of my body as in
motion； my body in this thought is so far absolute unity； and my
representation of it is a simple one； and hence I can indicate this
representation by the motion of a point； because I have made
abstraction of the size or volume of the body。 But I cannot hence
infer that； given merely the moving power of a body； the body may be
cogitated as simple substance； merely because the representation in my
mind takes no account of its content in space； and is consequently
simple。 The simple； in abstraction； is very different from the
objectively simple； and hence the Ego； which is simple in the first
sense； may； in the second sense； as indicating the soul itself； be a
very plex conception； with a very various content。 Thus it is
evident that in all such arguments there lurks a paralogism。 We
guess （for without some such surmise our suspicion would not be
excited in reference to a proof of this character） at the presence
of the paralogism； by keeping ever before us a criterion of the
possibility of those synthetical propositions which aim at proving
more than experience can teach us。 This criterion is obtained from the
observation that such proofs do not lead us directly from the
subject of the proposition to be proved to the required predicate； but
find it necessary to presuppose the possibility of extending our
cognition a priori by means of ideas。 We must； accordingly； always use
the greatest caution； we require； before attempting any proof； to
consider how it is possible to extend the sphere of cognition by the
operations of pure reason； and from what source we are to derive
knowledge； which is not obtained from the analysis of conceptions； nor
relates； by anticipation； to possible experience。 We shall thus
spare ourselves much severe and fruitless labour； by not expecting
from reason what is beyond its power； or rather by subjecting it to
discipline； and teaching it to moderate its vehement desires for the
extension of the sphere of cognition。
The first rule for our guidance is； therefore； not to attempt a
transcendental proof； before we have considered from what source we
are to derive the principles upon which the proof is to be based；
and what right we have to expect that our conclusions from these
principles will be veracious。 If they are principles of the
understanding； it is vain to expect that we should attain by their
means to ideas of pure reason； for these principles are valid only
in regard to objects of possible experience。 If they are principles of
pure reason； our labour is alike in vain。 For the principles of
reason； if employed as objective； are without exception dialectical
and possess no validity or truth； except as regulative principles of
the systematic employment of reason in experience。 But when such
delusive proof are presented to us； it is our duty to meet them with
the non liquet of a matured judgement； and； although we are unable
to expose the particular sophism upon which the proof is based； we
have a right to demand a deduction of the principles employed in it；
and； if these principles have their origin in pure reason alone；
such a deduction is absolutely impossible。 And thus it is
unnecessary that we should trouble ourselves with the exposure and
confutation of every sophistical illusion； we may； at once； bring
all dialectic； which is inexhaustible in the production of
fallacies； before the bar of critical reason； which tests the
principles upon which all dialectical procedure is based。 The second
peculiarity of transcendental proof is that a transcendental
proposition cannot rest upon more than a single proof。 If I am drawing
conclusions； not from conceptions； but from intuition corresponding to
a conception； be it pure intuition； as in mathematics； or empirical；
as in natural science； the intuition which forms the basis of my
inferences presents me with materials for many synthetical
propositions； which I can connect in various modes； while； as it is
allowable to proceed from different points in the intention； I can
arrive by different paths