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 exceptions to these laws； to employ new hypothesis in
support of the original one。 We employ the idea of the simple nature
of the human soul as the foundation of all the theories we may form of
its phenomena； but when we meet with difficulties in our way； when
we observe in the soul phenomena similar to the changes which take
place in matter； we require to call in new auxiliary hypotheses。 These
may； indeed； not be false； but we do not know them to be true； because
the only witness to their certitude is the hypothesis which they
themselves have been called in to explain。
We are not discussing the above…mentioned assertions regarding the
immaterial unity of the soul and the existence of a Supreme Being as
dogmata； which certain philosophers profess to demonstrate a priori；
but purely as hypotheses。 In the former case； the dogmatist must
take care that his arguments possess the apodeictic certainty of a
demonstration。 For the assertion that the reality of such ideas is
probable is as absurd as a proof of the probability of a proposition
in geometry。 Pure abstract reason； apart from all experience； can
either cognize nothing at all； and hence the judgements it enounces
are never mere opinions； they are either apodeictic certainties； or
declarations that nothing can be known on the subject。 Opinions and
probable judgements on the nature of things can only be employed to
explain given phenomena； or they may relate to the effect； in
accordance with empirical laws； of an actually existing cause。 In
other words； we must restrict the sphere of opinion to the world of
experience and nature。 Beyond this region opinion is mere invention；
unless we are groping about for the truth on a path not yet fully
known； and have some hopes of stumbling upon it by chance。
But； although hypotheses are inadmissible in answers to the
questions of pure speculative reason； they may be employed in the
defence of these answers。 That is to say； hypotheses are admissible in
polemic； but not in the sphere of dogmatism。 By the defence of
statements of this character； I do not mean an attempt at
discovering new grounds for their support； but merely the refutation
of the arguments of opponents。 All a priori synthetical propositions
possess the peculiarity that； although the philosopher who maintains
the reality of the ideas contained in the proposition is not in
possession of sufficient knowledge to establish the certainty of his
statements； his opponent is as little able to prove the truth of the
opposite。 This equality of fortune does not allow the one party to
be superior to the other in the sphere of speculative cognition； and
it is this sphere； accordingly； that is the proper arena of these
endless speculative conflicts。 But we shall afterwards show that； in
relation to its practical exercise； Reason has the right of
admitting what； in the field of pure speculation； she would not be
justified in supposing； except upon perfectly sufficient grounds；
because all such suppositions destroy the necessary pleteness of
speculation… a condition which the practical reason； however； does not
consider to be requisite。 In this sphere； therefore； Reason is
mistress of a possession； her title to which she does not require to
prove… which； in fact； she could not do。 The burden of proof
accordingly rests upon the opponent。 But as he has just as little
knowledge regarding the subject discussed； and is as little able to
prove the non…existence of the object of an idea； as the philosopher
on the other side is to demonstrate its reality； it is evident that
there is an advantage on the side of the philosopher who maintains his
proposition as a practically necessary supposition （melior est
conditio possidentis）。 For he is at liberty to employ； in
self…defence； the same weapons as his opponent makes use of in
attacking him； that is； he has a right to use hypotheses not for the
purpose of supporting the arguments in favour of his own propositions；
but to show that his opponent knows no more than himself regarding the
subject under 'discussion and cannot boast of any speculative
advantage。
Hypotheses are； therefore； admissible in the sphere of pure reason
only as weapons for self…defence； and not as supports to dogmatical
assertions。 But the opposing party we must always seek for in
ourselves。 For speculative reason is； in the sphere of
transcendentalism； dialectical in its own nature。 The difficulties and
objections we have to fear lie in ourselves。 They are like old but
never superannuated claims； and we must seek them out； and settle them
once and for ever； if we are to expect a permanent peace。 External
tranquility is hollow and unreal。 The root of these contradictions；
which lies in the nature of human reason； must be destroyed； and
this can only be done by giving it； in the first instance； freedom
to grow； nay； by nourishing it； that it may send out shoots； and
thus betray its own existence。 It is our duty； therefore； to try to
discover new objections； to put weapons in the bands of our
opponent； and to grant him the most favourable position in the arena
that he can wish。 We have nothing to fear from these concessions； on
the contrary； we may rather hope that we shall thus make ourselves
master of a possession which no one will ever venture to dispute。
The thinker requires； to be fully equipped； the hypotheses of pure
reason； which； although but leaden weapons （for they have not been
steeled in the armoury of experience）； are as useful as any that can
be employed by his opponents。 If； accordingly； we have assumed； from a
non…speculative point of view； the immaterial nature of the soul；
and are met by the objection that experience seems to prove that the
growth and decay of our mental faculties are mere modifications of the
sensuous organism… we can weaken the force of this objection by the
assumption that the body is nothing but the fundamental phenomenon； to
which； as a necessary condition； all sensibility； and consequently all
thought； relates in the present state of our existence； and that the
separation of soul and body forms the conclusion of the sensuous
exercise of our power of cognition and the beginning of the
intellectual。 The body would； in this view of the question； be
regarded； not as the cause of thought； but merely as its restrictive
condition； as promotive of the sensuous and animal； but as a hindrance
to the pure and spiritual life； and the dependence of the animal
life on the constitution of the body； would not prove that the whole
life of man was also dependent on the state of the organism。 We
might go still farther； and discover new objections； or carry out to
their extreme consequences those which have already been adduced。
Generation； in the human race as well as among the irrational
animals； depends on so many accidents… of occasion； of proper
sustenance； of the laws enacted by the government of a country of vice
even； that it is difficult to believe in the eternal existence of a
being whose life has begun under circumstances so mean and trivial；
and so entirely dependent upon our own control。 As regards the
continuance of the existence of the whole race； we need have no
difficulties； for accident in single cases is subject to general laws；
but； in the case of each individual； it would seem as if we could
hardly expect so wonderful an effect from causes so insignificant。
But； in answer to these objections； we may adduce the transcendental
hypothesis that all life is properly intelligible； and not subject
to changes of time； and that it neither began in birth； nor will end
in death。 We may assume that this life is nothing more than a sensuous
representation of pure spiritual life； that the whole world of sense
is but an image； hovering before the faculty of cognition which we
exercise in this sphere； and with no more objective reality than a
dream； and that if we could intuite ourselves and other things as they
really are； we should see ourselves in a world of spiritual natures；
our connection with which did not begin at our birth and will not
cease with the destruction of the body。 And so on。
We cannot be said to know what has been above asserted； nor do we
seriously maintain the truth of these assertions； and the notions
therein indicated are not even ideas of reason； they are purely
fictitious conceptions。 But this hypothetical procedure is in
perfect conformity with the laws of reason。 Our opponent mistakes
the absence of empirical conditions for a proof of the plete
impossibility of all that we have asserted； and we have to show him
that be has not exhausted the whole sphere of possibility and that
he can as little pass that sphere by the laws of experience and
nature； as we can lay a secure foundation for the operations of reason
beyond the region of experience。 Such hypothetical defences against
the pretensions of an opponent must not be regarded as declarations of
opinion。 The philosopher abandons them； so soon as the opposite
party renounces its dogmatical conceit。 To m