itself）… I mean the faculty of freedom。 The moral law； which itself
does not require a justification； proves not merely the possibility of
freedom； but that it really belongs to beings who recognize this law
as binding on themselves。 The moral law is in fact a law of the
causality of free agents and； therefore； of the possibility of a
supersensible system of nature； just as the metaphysical law of events
in the world of sense was a law of causality of the sensible system of
nature； and it therefore determines what speculative philosophy was
pelled to leave undetermined； namely； the law for a causality；
the concept of which in the latter was only negative； and therefore
for the first time gives this concept objective reality。
This sort of credential of the moral law； viz。； that it is set forth
as a principle of the deduction of freedom； which is a causality of
pure reason； is a sufficient substitute for all a priori
justification； since theoretic reason was pelled to assume at least
the possibility of freedom； in order to satisfy a want of its own。 For
the moral law proves its reality； so as even to satisfy the critique
of the speculative reason； by the fact that it adds a positive
definition to a causality previously conceived only negatively； the
possibility of which was inprehensible to speculative reason； which
yet was pelled to suppose it。 For it adds the notion of a reason
that directly determines the will （by imposing on its maxims the
condition of a universal legislative form）； and thus it is able for
the first time to give objective； though only practical； reality to
reason； which always became transcendent when it sought to proceed
speculatively with its ideas。 It thus changes the transcendent use
of reason into an immanent use （so that reason is itself； by means
of ideas； an efficient cause in the field of experience）。
The determination of the causality of beings in the world of
sense； as such； can never be unconditioned； and yet for every series
of conditions there must be something unconditioned； and therefore
there must be a causality which is determined wholly by itself。 Hence；
the idea of freedom as a faculty of absolute spontaneity was not found
to be a want but； as far as its possibility is concerned； an
analytic principle of pure speculative reason。 But as it is absolutely
impossible to find in experience any example in accordance with this
idea； because amongst the causes of things as phenomena it would be
impossible to meet with any absolutely unconditioned determination
of causality； we were only able to defend our supposition that a
freely acting cause might be a being in the world of sense； in so
far as it is considered in the other point of view as a noumenon；
showing that there is no contradiction in regarding all its actions as
subject to physical conditions so far as they are phenomena； and yet
regarding its causality as physically unconditioned； in so far as
the acting being belongs to the world of understanding； and in thus
making the concept of freedom the regulative principle of reason。 By
this principle I do not indeed learn what the object is to which
that sort of causality is attributed； but I remove the difficulty；
for； on the one side； in the explanation of events in the world； and
consequently also of the actions of rational beings； I leave to the
mechanism of physical necessity the right of ascending from
conditioned to condition ad infinitum； while on the other side I
keep open for speculative reason the place which for it is vacant；
namely； the intelligible； in order to transfer the unconditioned
thither。 But I was not able to verify this supposition； that is； to
change it into the knowledge of a being so acting； not even into the
knowledge of the possibility of such a being。 This vacant place is now
filled by pure practical reason with a definite law of causality in an
intelligible world （causality with freedom）； namely； the moral law。
Speculative reason does not hereby gain anything as regards its
insight； but only as regards the certainty of its problematical notion
of freedom； which here obtains objective reality； which； though only
practical； is nevertheless undoubted。 Even the notion of causality…
the application； and consequently the signification； of which holds
properly only in relation to phenomena； so as to connect them into
experiences （as is shown by the Critique of Pure Reason）… is not so
enlarged as to extend its use beyond these limits。 For if reason
sought to do this； it would have to show how the logical relation of
principle and consequence can be used synthetically in a different
sort of intuition from the sensible； that is how a causa noumenon is
possible。 This it can never do； and； as practical reason； it does
not even concern itself with it； since it only places the
determining principle of causality of man as a sensible creature
（which is given） in pure reason （which is therefore called practical）；
and therefore it employs the notion of cause； not in order to know
objects； but to determine causality in relation to objects in general。
It can abstract altogether from the application of this notion to
objects with a view to theoretical knowledge （since this concept is
always found a priori in the understanding even independently of any
intuition）。 Reason； then； employs it only for a practical purpose； and
hence we can transfer the determining principle of the will into the
intelligible order of things； admitting； at the same time； that we
cannot understand how the notion of cause can determine the
knowledge of these things。 But reason must cognise causality with
respect to the actions of the will in the sensible world in a definite
manner； otherwise； practical reason could not really produce any
action。 But as to the notion which it forms of its own causality as
noumenon； it need not determine it theoretically with a view to the
cognition of its supersensible existence； so as to give it
significance in this way。 For it acquires significance apart from
this； though only for practical use； namely； through the moral law。
Theoretically viewed； it remains always a pure a priori concept of the
understanding； which can be applied to objects whether they have
been given sensibly or not； although in the latter case it has no
definite theoretical significance or application； but is only a
formal； though essential； conception of the understanding relating
to an object in general。 The significance which reason gives it
through the moral law is merely practical； inasmuch as the idea of the
idea of the law of causality （of the will） has self causality； or is
its determining principle。
II。 Of the Right that Pure Reason in its Practical use has to an
Extension which is not possible to it in its Speculative Use。
We have in the moral principle set forth a law of causality； the
determining principle of which is set above all the conditions of
the sensible world； we have it conceived how the will； as belonging to
the intelligible world； is determinable； and therefore we therefore we
have its subject （man） not merely conceived as belonging to a world of
pure understanding； and in this respect unknown （which the critique of
speculative reason enabled us to do）； but also defined as regards
his causality by means of a law which cannot be reduced to any
physical law of the sensible world； and therefore our knowledge is
extended beyond the limits of that world； a pretension which the
Critique of Pure Reason declared to be futile in all speculation。 Now；
how is the practical use of pure reason here to be reconciled with the
theoretical； as to the determination of the limits of its faculty？
David Hume； of whom we may say that he menced the assault on
the claims of pure reason； which made a thorough investigation of it
necessary； argued thus： The notion of cause is a notion that
involves the necessity of the connexion of the existence of
different things （and that； in so far as they are different）； so that；
given A； I know that something quite distinct there from； namely B；
must necessarily also exist。 Now necessity can be attributed to a
connection； only in so far as it is known a priori； for experience
would only enable us to know of such a connection that it exists；
not that it necessarily exists。 Now； it is impossible； says he； to
know a priori and as necessary the connection between one thing and
another （or between one attribute and another quite distinct） when
they have not been given in experience。 Therefore the notion of a
cause is fictitious and delusive and； to speak in the mildest way；
is an illusion； only excusable inasmuch as the custom （a subjective
necessity） of perceiving certain things； or their attributes as
often associated in existence along with or in succession to one
another； is insensibly taken for an objective necessity of supposing
such a connection in the objects themselves； and thus the notion of
a cause has been acquired surreptitiously and not legitimately； nay；
it can never be so acquired or authenticated； since it demands a
connection in itself vain； chimerical； and untenable in presence of
reason； and to which no object can e