But the opposite point of view might also be taken. It might be said that after all every kind of knowledge is practical, and our own deduction of the meaning of science might be said to suggest such interpretation. We acknowledged at the outset that the so-called theoretical knowledge is by no means a passive mirror picture of an independent outside world; but that in every judgment real experience is remoulded and reshaped in the service of certain purposes of will. Here lies the true core of that growing popular philosophy of to-day which, under the name of pragmatism, or under other titles, mingles the purposive character of our knowledge and the evolutionary theories of modern biology in the vague notion that men created knowledge because the biological struggle for existence led to such views of the world; and that we call true that correlation of our experiences which has approved itself through its harmony with the phylogenetic development. Certainly we must reject such circle philosophies. We must see clearly that the whole conception of a biological development and of a struggle of organisms is itself only a part of our construction of causal knowledge. We must have knowledge to conceive ourselves as products of a phylogenetic history, and thus cannot deduce from it the fact, and, still less, the justification of knowledge. Yet one element of this theory remains valuable: knowledge is indeed a purposive activity, a reconstruction of the world in the service of ideals of the will. We have thus from one side the suggestion that all knowledge is merely theoretical, from the other side the claim that all knowledge is practical activity. It seems as if both sides might agree that it is superfluous and unjustified to make a demarcation line through the field of knowledge and to separate two sorts of knowledge, theoretical and practical. For both theories demand that all knowledge be of one kind, and they disagree only as to whether we ought to call it all theoretical or all practical.