IV. The very copious empirical element that fills the books on the Philosophy of the practical and the attempt to treat it philosophically have also had the injurious effect of distracting their authors from entering deeply into the problems of true and proper philosophy, to which the practical activity gives rise. Thus a history of the aforesaid aberrations would be as rich as a history of the speculation as to the will would be poor. The problem of the theoretic element in the volitional act, or of the theoretic phase of deliberation, has not been developed as it deserved, and as the important pages of the third and seventh books of the _Ethica Nicomachea_ seemed to augur. The question, too, of the priority of the will over the concepts of the useful and of the good and of the practical judgments, is hardly touched by a philosopher here and there, and the Herbartian theory of practical judgments failed to excite any fervour of examination, criticism, or opposition. The concept of good will and of good intention, to which Kant gave a prominent place, is not discussed profoundly, save by Hegel, who goes deeply into the difficult problems of abstract and concrete intention in the introduction and in the second section of the _Philosophy of Law._ The other problem, as to the possibility or impossibility of willing without full knowledge, was not adequately treated after Descartes and Spinoza. [Sidenote: _The practical nature of error._] In Descartes are also to be found the most acute observations as to the practical nature of error. After having stated that it is impossible that God should have given to man any faculty that was not perfect of its kind, he asks himself: "_D'où est-ce donc que naissent mes erreurs? C'est à savoir, de cela seul que la volonté, étant beaucoup plus ample et plus étendue que l'entendement, je ne la contiens pas dans les mêmes limites, mais que je l'étends aussi aux choses que je n'entends pas; auxquelles étant de soi indifférente, elle s'égare fort aisément, et choisit le faux pour le vrai et le mal pour le bien: ce qui fait que je me trompe et je pèche._" Errors arise from the concourse of two causes, the faculty of knowing and the faculty of choice: "_car pour l'entendement seul je n'assure ni ne nie aucune chose, mais je conçois seulement les idées des choses que je puis assurer ou nier._"[22] For Descartes the affirmation was an act of the will, and here perhaps lies his mistake and the mistake of those who have followed him in this theory (Rosmini for example); that is to say, they have _mistaken_ the _affirmation,_ which is theoretical, for the _communication,_ which is practical, or they have taken as being of the same degree the general will that is in affirmation through the unity of the spirit, and the particular will that is in error. Spinoza opposes Descartes' theory of error, but in conformity with the deterministic nature of his philosophy, his criticism relates only to the point as to whether