| The existence of practical freedom can be proved from experience alone. |
| For the human will is not determined by that alone which immediately affects the senses; on the contrary, we have the power, by calling up the notion of what is useful or hurtful in a more distant relation, of overcoming the immediate impressions on our sensuous faculty of desire. |
| But these considerations of what is desirable in relation to our whole state, that is, is in the end good and useful, are based entirely upon reason. |
| This faculty, accordingly, enounces laws, which are imperative or objective laws of freedom and which tell us what ought to take place, thus distinguishing themselves from the laws of nature, which relate to that which does take place. |
| The laws of freedom or of free will are hence termed practical laws. |
| Whether reason is not itself, in the actual delivery of these laws, determined in its turn by other influences, and whether the action which, in relation to sensuous impulses, we call free, may not, in relation to higher and more remote operative causes, really form a part of nature--these are questions which do not here concern us. |
| They are purely speculative questions; and all we have to do, in the practical sphere, is to inquire into the rule of conduct which reason has to present. |
| Experience demonstrates to us the existence of practical freedom as one of the causes which exist in nature, that is, it shows the causal power of reason in the determination of the will. |
| The idea of transcendental freedom, on the contrary, requires that reason--in relation to its causal power of commencing a series of phenomena--should be independent of all sensuous determining causes; and thus it seems to be in opposition to the law of nature and to all possible experience. |
| It therefore remains a problem for the human mind. |
| But this problem does not concern reason in its practical use; and we have, therefore, in a canon of pure reason, to do with only two questions, which relate to the practical interest of pure reason; Is there a God? |
| and, Is there a future life? |
| The question of transcendental freedom is purely speculative, and we may therefore set it entirely aside when we come to treat of practical reason. |
| Besides, we have already discussed this subject in the antinomy of pure reason. |
| SECTION II. Of the Ideal of the Summum Bonum as a Determining Ground of the Ultimate End of Pure Reason. |
| Reason conducted us, in its speculative use, through the field of experience and, as it can never find complete satisfaction in that sphere, from thence to speculative ideas--which, however, in the end brought us back again to experience, and thus fulfilled the purpose of reason, in a manner which, though useful, was not at all in accordance with our expectations. |
| It now remains for us to consider whether pure reason can be employed in a practical sphere, and whether it will here conduct us to those ideas which attain the highest ends of pure reason, as we have just stated them. |
| We shall thus ascertain whether, from the point of view of its practical interest, reason may not be able to supply us with that which, on the speculative side, it wholly denies us. |
| The whole interest of reason, speculative as well as practical, is centred in the three following questions: |
| 1. WHAT CAN I KNOW? |
| 2. WHAT OUGHT I TO DO? |