understanding and the dialectical pretensions of reason； against
which； however； his attacks are mainly directed； reason does not
feel itself shut out from all attempts at the extension of a priori
cognition； and hence it refuses； in spite of a few checks in this or
that quarter； to relinquish such efforts。 For one naturally arms
oneself to resist an attack； and bees more obstinate in the resolve
to establish the claims he has advanced。 But a plete review of
the powers of reason； and the conviction thence arising that we are in
possession of a limited field of action； while we must admit the
vanity of higher claims； puts an end to all doubt and dispute； and
induces reason to rest satisfied with the undisturbed possession of
its limited domain。
To the uncritical dogmatist； who has not surveyed the sphere of
his understanding； nor determined； in accordance with principles；
the limits of possible cognition； who； consequently； is ignorant of
his own powers； and believes he will discover them by the attempts
he makes in the field of cognition； these attacks of scepticism are
not only dangerous； but destructive。 For if there is one proposition
in his chain of reasoning which be he cannot prove； or the fallacy
in which be cannot evolve in accordance with a principle； suspicion
falls on all his statements； however plausible they may appear。
And thus scepticism； the bane of dogmatical philosophy； conducts
us to a sound investigation into the understanding and the reason。
When we are thus far advanced； we need fear no further
attacks； for the limits of our domain are clearly marked out； and we
can make no claims nor bee involved in any disputes regarding the
region that lies beyond these limits。 Thus the sceptical procedure
in philosophy does not present any solution of the problems of reason；
but it forms an excellent exercise for its powers； awakening its
circumspection； and indicating the means whereby it may most fully
establish its claims to its legitimate possessions。
SECTION III。 The Discipline of Pure Reason in Hypothesis。
This critique of reason has now taught us that all its efforts to
extend the bounds of knowledge； by means of pure speculation； are
utterly fruitless。 So much the wider field； it may appear； lies open
to hypothesis； as； where we cannot know with certainty； we are at
liberty to make guesses and to form suppositions。
Imagination may be allowed； under the strict surveillance of reason；
to invent suppositions； but； these must be based on something that
is perfectly certain… and that is the possibility of the object。 If we
are well assured upon this point； it is allowable to have recourse
to supposition in regard to the reality of the object； but this
supposition must； unless it is utterly groundless； be connected； as
its ground of explanation； with that which is really given and
absolutely certain。 Such a supposition is termed a hypothesis。
It is beyond our power to form the least conception a priori of
the possibility of dynamical connection in phenomena； and the category
of the pure understanding will not enable us to ex。 cogitate any
such connection； but merely helps us to understand it； when we meet
with it in experience。 For this reason we cannot； in accordance with
the categories； imagine or invent any object or any property of an
object not given； or that may not be given in experience； and employ
it in a hypothesis； otherwise； we should be basing our chain of
reasoning upon mere chimerical fancies； and not upon conceptions of
things。 Thus； we have no right to assume the existence of new
powers； not existing in nature… for example； an understanding with a
non…sensuous intuition； a force of attraction without contact； or some
new kind of substances occupying space； and yet without the property
of impenetrability… and； consequently； we cannot assume that there
is any other kind of munity among substances than that observable
in experience； any kind of presence than that in space； or any kind of
duration than that in time。 In one word； the conditions of possible
experience are for reason the only conditions of the possibility of
things； reason cannot venture to form； independently of these
conditions； any conceptions of things； because such conceptions；
although not self…contradictory； are without object and without
application。
The conceptions of reason are； as we have already shown； mere ideas；
and do not relate to any object in any kind of experience。 At the same
time； they do not indicate imaginary or possible objects。 They are
purely problematical in their nature and； as aids to the heuristic
exercise of the faculties； form the basis of the regulative principles
for the systematic employment of the understanding in the field of
experience。 If we leave this ground of experience； they bee mere
fictions of thought； the possibility of which is quite indemonstrable；
and they cannot； consequently； be employed as hypotheses in the
explanation of real phenomena。 It is quite admissible to cogitate
the soul as simple； for the purpose of enabling ourselves to employ
the idea of a perfect and necessary unity of all the faculties of
the mind as the principle of all our inquiries into its internal
phenomena； although we cannot cognize this unity in concreto。 But to
assume that the soul is a simple substance （a transcendental
conception） would be enouncing a proposition which is not only
indemonstrable… as many physical hypotheses are… but a proposition
which is purely arbitrary； and in the highest degree rash。 The
simple is never presented in experience； and； if by substance is
here meant the permanent object of sensuous intuition； the possibility
of a simple phenomenon is perfectly inconceivable。 Reason affords no
good grounds for admitting the existence of intelligible beings； or of
intelligible properties of sensuous things； although… as we have no
conception either of their possibility or of their impossibility… it
will always be out of our power to affirm dogmatically that they do
not exist。 In the explanation of given phenomena； no other things
and no other grounds of explanation can be employed than those which
stand in connection with the given phenomena according to the known
laws of experience。 A transcendental hypothesis； in which a mere
idea of reason is employed to explain the phenomena of nature； would
not give us any better insight into a phenomenon； as we should be
trying to explain what we do not sufficiently understand from known
empirical principles； by what we do not understand at all。 The
principles of such a hypothesis might conduce to the satisfaction of
reason； but it would not assist the understanding in its application
to objects。 Order and conformity to aims in the sphere of nature
must be themselves explained upon natural grounds and according to
natural laws； and the wildest hypotheses； if they are only physical；
are here more admissible than a hyperphysical hypothesis； such as that
of a divine author。 For such a hypothesis would introduce the
principle of ignava ratio； which requires us to give up the search for
causes that might be discovered in the course of experience and to
rest satisfied with a mere idea。 As regards the absolute totality of
the grounds of explanation in the series of these causes； this can
be no hindrance to the understanding in the case of phenomena；
because； as they are to us nothing more than phenomena； we have no
right to look for anything like pleteness in the synthesis of the
series of their conditions。
Transcendental hypotheses are therefore inadmissible； and we
cannot use the liberty of employing； in the absence of physical；
hyperphysical grounds of explanation。 And this for two reasons； first；
because such hypothesis do not advance reason； but rather stop it in
its progress； secondly； because this licence would render fruitless
all its exertions in its own proper sphere； which is that of
experience。 For； when the explanation of natural phenomena happens
to be difficult； we have constantly at hand a transcendental ground of
explanation； which lifts us above the necessity of investigating
nature； and our inquiries are brought to a close； not because we
have obtained all the requisite knowledge； but because we abut upon
a principle which is inprehensible and which； indeed； is so far
back in the track of thought as to contain the conception of the
absolutely primal being。
The next requisite for the admissibility of a hypothesis is its
sufficiency。 That is； it must determine a priori the consequences
which are given in experience and which are supposed to follow from
the hypothesis itself。 If we require to employ auxiliary hypotheses；
the suspicion naturally arises that they are mere fictions； because
the necessity for each of them requires the same justification as in
the case of the original hypothesis； and thus their testimony is
invalid。 If we suppose the existence of an infinitely perfect cause；
we possess sufficient grounds for the explanation of the conformity to
aims； the order and the greatness which we observe in the universe；
but we find ourselves obliged； when we observe the evil in the world
and the ex