merely subjective principle of assent, which, however, is
objectively valid for a reason equally pure but practical, and this
principle, by means of the concept of freedom, assures objective
reality and authority to the ideas of God and immortality. Nay,
there is a subjective necessity (a need of pure reason) to assume
them. Nevertheless the theoretical knowledge of reason is not hereby
enlarged, but only the possibility is given, which heretofore was
merely a problem and now becomes assertion, and thus the practical use
of reason is connected with the elements of theoretical reason. And
this need is not a merely hypothetical one for the arbitrary
purposes of speculation, that we must assume something if we wish in
speculation to carry reason to its utmost limits, but it is a need
which has the force of law to assume something without which that
cannot be which we must inevitably set before us as the aim of our
action.



{PREFACE ^paragraph 5}

* Lest any one should imagine that he finds an inconsistency here
when I call freedom the condition of the moral law, and hereafter
maintain in the treatise itself that the moral law is the condition
under which we can first become conscious of freedom, I will merely
remark that freedom is the ratio essendi of the moral law, while the
moral law is the ratio cognoscendi of freedom. For Pad not the moral
law been previously distinctly thought in our reason, we should
never consider ourselves justified in assuming such a thing as
freedom, although it be not contradictory. But were there no freedom
it would be impossible to trace the moral law in ourselves at all.