Page 40 of 45
From these remarks, the reader of the Critique of Pure Speculative Reason will be thoroughly convinced how highly necessary that laborious deduction of the categories was, and how fruitful for theology and morals. For if, on the one hand, we place them in pure understanding, it is by this deduction alone that we can be prevented from regarding them, with Plato, as innate, and founding on them extravagant pretensions to theories of the supersensible, to which we can see no end, and by which we should make theology a magic lantern of chimeras; on the other hand, if we regard them as acquired, this deduction saves us from restricting, with Epicurus, all and every use of them, even for practical purposes, to the objects and motives of the senses. But now that the Critique has shown by that deduction, first, that they are not of empirical origin, but have their seat and source a priori in the pure understanding; secondly, that as they refer to objects in general independently of the intuition of them, hence, although they cannot effect theoretical knowledge, except in application to empirical objects, yet when applied to an object given by pure practical reason they enable us to conceive the supersensible definitely, only so far, however, as it is defined by such predicates as are necessarily connected with the pure practical purpose given a priori and with its possibility. The speculative restriction of pure reason and its practical extension bring it into that relation of equality in which reason in general can be employed suitably to its end, and this example proves better than any other that the path to wisdom, if it is to be made sure and not to be impassable or misleading, must with us men inevitably pass through science; but it is not till this is complete that we can be convinced that it leads to this goal.
BOOK2|CHAPTER2 ^paragraph 85
A want or requirement of pure reason in its speculative use leads only to a hypothesis; that of pure practical reason to a postulate; for in the former case I ascend from the result as high as I please in the series of causes, not in order to give objective reality to the result (e.g., the causal connection of things and changes in the world), but in order thoroughly to satisfy my inquiring reason in respect of it. Thus I see before me order and design in nature, and need not resort to speculation to assure myself of their reality, but to explain them I have to presuppose a Deity as their cause; and then since the inference from an effect to a definite cause is always uncertain and doubtful, especially to a cause so precise and so perfectly defined as we have to conceive in God, hence the highest degree of certainty to which this pre-supposition can be brought is that it is the most rational opinion for us men. * On the other hand, a requirement of pure practical reason is based on a duty, that of making something (the summum bonum) the object of my will so as to promote it with all my powers; in which case I must suppose its possibility and, consequently, also the conditions necessary thereto, namely, God, freedom, and immortality; since I cannot prove these by my speculative reason, although neither can I refute them. This duty is founded on something that is indeed quite independent of these suppositions and is of itself apodeictically certain, namely, the moral law; and so far it needs no further support by theoretical views as to the inner constitution of things, the secret final aim of the order of the world, or a presiding ruler thereof, in order to bind me in the most perfect manner to act in unconditional conformity to the law. But the subjective effect of this law, namely, the mental disposition conformed to it and made necessary by it, to promote the practically possible summum bonum, this pre-supposes at least that the latter is possible, for it would be practically impossible to strive after the object of a conception which at bottom was empty and had no object. Now the above-mentioned postulates concern only the physical or metaphysical conditions of the possibility of the summum bonum; in a word, those which lie in the nature of things; not, however, for the sake of an arbitrary speculative purpose, but of a practically necessary end of a pure rational will, which in this case does not choose, but obeys an inexorable command of reason, the foundation of which is objective, in the constitution of things as they must be universally judged by pure reason, and is not based on inclination; for we are in nowise justified in assuming, on account of what we wish on merely subjective grounds, that the means thereto are possible or that its object is real. This, then, is an absolutely necessary requirement, and what it pre-supposes is not merely justified as an allowable hypothesis, but as a postulate in a practical point of view; and admitting that the pure moral law inexorably binds every man as a command (not as a rule of prudence), the righteous man may say: "I will that there be a God, that my existence in this world be also an existence outside the chain of physical causes and in a pure world of the understanding, and lastly, that my duration be endless; I firmly abide by this, and will not let this faith be taken from me; for in this instance alone my interest, because I must not relax anything of it, inevitably determines my judgement, without regarding sophistries, however unable I may be to answer them or to oppose them with others more plausible. **
* But even here we should not be able to allege a
requirement of reason, if we had not before our eyes a
problematical, but yet inevitable, conception of reason,
namely, that of an absolutely necessary being. This
conception now seeks to be defined, and this, in addition to
the tendency to extend itself, is the objective ground of a
requirement of speculative reason, namely, to have a more
precise definition of the conception of a necessary being
which is to serve as the first cause of other beings, so as
to make these latter knowable by some means. Without such
antecedent necessary problems there are no requirements- at
least not of pure reason- the rest are requirements of
inclination.
BOOK2|CHAPTER2 ^paragraph 90
** In the Deutsches Museum, February, 1787, there is a
dissertation by a very subtle and clear-headed man, the late
Wizenmann, whose early death is to be lamented, in which he
disputes the right to argue from a want to the objective
reality of its object, and illustrates the point by the
example of a man in love, who having fooled himself into an
idea of beauty, which is merely a chimera of his own brain,
would fain conclude that such an object really exists
somewhere. I quite agree with him in this, in all cases
where the want is founded on inclination, which cannot
necessarily postulate the existence of its object even for
the man that is affected by it, much less can it contain a
demand valid for everyone, and therefore it is merely a
subjective ground of the wish. But in the present case we
have a want of reason springing from an objective
determining principle of the will, namely, the moral law,
which necessarily binds every rational being, and therefore
justifies him in assuming a priori in nature the conditions
proper for it, and makes the latter inseparable from the
complete practical use of reason. It is a duty to realize
the summum bonum to the utmost of our power, therefore it
must be possible, consequently it is unavoidable for every
rational being in the world to assume what is necessary for
its objective possibility. The assumption is as necessary as
the moral law, in connection with which alone it is valid.
