pletion of which any
popularizing might have waited), kept free from admixture of
Anthropology, Theology, Physics, Hyperphysics, &c., and setting forth
the conception of Duty as purely rational, without the confusion of
empirical motives. To a metaphysic of this kind, Kant is now to ascend
from the popular philosophy, with its stock-in-trade of single
instances, following out the practical faculty of Reason from the
general rules determining it, to the point where the conception of Duty
emerges.

While things in nature work according to laws, rational beings alone
can act according to a conceived idea of laws, _i.e._, to principles.
This is to have a Will, or, what is the same, Practical Reason, reason
being required in deducing actions from laws. If the Will follows
Reason exactly and without fail, actions objectively necessary are
necessary also subjectively; if, through subjective conditions
(inclinations, &c.), the Will does not follow Reason inevitably,
objectively necessary actions become subjectively contingent, and
towards the objective laws the attitude of the will is no longer
unfailing choice, but _constraint_. A constraining objective principle
mentally represented, is a _command_; its formula is called
_Imperative_, for which the expression is _Ought_. A will perfectly
good--_i.e._, subjectively determined to follow the objective laws of
good as soon as conceived--knows no Ought. Imperatives are only for an
imperfect, such as is the human, will. _Hypothetical_ Imperatives
represent the practical necessity of an action as a means to an end,
being _problematical_ or _assertory_ principles, according as the end
is possible or real. _Categorical_ Imperatives represent an action as
objectively necessary for itself, and count as _apodeictical_
principles.

To the endless number of possible aims of human action correspond as
many Imperatives, directing merely how they are to be attained, without
any question of their value; these are Imperatives of _Fitness_. To one
real aim, existing necessarily for all rational beings, viz.,
Happiness, corresponds the Imperative of _Prudence_ (in the narrow
sense), being assertory while hypothetical. The categorical Imperative,
enjoining a mode of action for itself, and concerned about the form and
principle of it, not its nature and result, is the Imperative of
_Morality_. These various kinds of Imperatives, as influencing the
will, may be distinguished as _Rules_ (of fitnes