The Interplay of Cognitive and Practical Reason: A Critical Perspective
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Every psychological phenomenon is a cognitive phenomenon. Although cognitive psychology is concerned with all human activity, the concern is from a particular point of view. Other viewpoints (like Dynamic psychology which begins with motives rather than sensory input) are also legitimate and necessary.
The a priori principles of two faculties of the mind viz cognition and desire need to be determined. However dissimilar ideas of objects may be, though they be ideas of understanding, or even of reason in contrast to ideas of sense.
The theoretical (speculative) use of reason is concerned with objects of cognitive faculty only, and a critique of it with reference to this use applied properly to the pure faculty of cognition. It is different from the practical use of reason (concerned with grounds of determination of the will - a faculty either to produce objects corresponding to ideas, or to determine our causality).
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Can pure reason alone suffice to determine the will a priori, or whether it can be a ground of determination only as dependent on empirical conditions? Now, comes in a notion of causality justified by the critique of pure reason, although not capable of being presented empirically, viz., that of freedom; and if we can now discover means of proving that this property does in fact belong to the human will, then it will be shown that pure reason can be practical; consequently, we shall have to make a critical examination, not of pure practical reason, but only of practical reason generally. The critique, then, of practical reason is bound to prevent the empirically conditioned reason from claiming exclusively to furnish the ground of determination of the will. If it is proved that there is a [practical] reason, its employment is alone immanent and constitutive; the empirically conditioned use, which claims supremacy, is on the contrary transcendent and expresses itself in demands which go quite beyond its sphere. This is just the opposite of pure reason in its speculative employment, in its use of the concept of causality in order to escape the antimony into which it inevitably falls. Being merely regulative, speculative reason exhibits the concept as a problem lest the supposed impossibility of what it must at least allow to be thinkable should endanger its very being.
We deny objective reality to the super-sensible use of the categories in speculation and yet admit this reality with respect to the objects of pure practical reason… Practical reason itself, without any concert with the speculative, assures reality to a super-sensible object of the category of causality, viz., freedom, although only for practical use; and this establishes on the evidence of a fact that which in the former case could only be conceived problematically.
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The reality of freedom concept is proved by an apodeictic law of practical reason, it is the key-stone of the pure reason system, even the speculative. Though the summum bonum may be the whole object of a practical reason, i.e., a pure will, yet it is not on that account to be regarded as its determining principle.
