To the physical and physiological objections against so-called "Naïve Realism" Hartmann adds some further objections which he describes as philosophical in the strict sense. A logical examination of the physical and physiological objections reveals that, after all, the desired conclusion can be reached only if we start from the existence and nexus of external objects, just as these are assumed by the ordinary naïve consciousness, and then inquire how this external world can enter the consciousness of beings with organisms such as ours. We have seen that every trace of such an external world is lost on the way from the impression on the sense-organ to the appearance of the sensation in our consciousness, and that in the latter nothing survives except our ideas. Hence, we have to assume that the picture of the external world which we actually have, has been built up by the soul on the basis of the sensations given to it. First, the soul constructs out of the data of the senses of touch and sight a picture of the world in space, and then the sensations of the other senses are fitted into this space-system. When we are compelled to think of a certain complex of sensations as belonging together, we are led to the concept of substance and regard substance as the bearer of sense-qualities. When we observe that some sense-qualities disappear from a substance and that others appear in their place, we ascribe this event in the world of phenomena to a change regulated by the law of causality. Thus, according to this view, our whole world-picture is composed of subjective sensations which are ordered by the activity of our own souls. Hartmann says, "What the subject perceives is always only modifications of its own psychic states and nothing else." [45] Now let us ask ourselves, How do we come by such a view? The bare skeleton of the line of thought which leads to it is as follows. Supposing an external world exists, we do not perceive it as such but transform it through our organisation into a world of ideas. This is a supposition which, when consistently thought out, destroys itself. But is this reflection capable of supporting any positive alternative? Are we justified in regarding the world, which is given to us, as the subjective content of ideas because the assumptions of the naïve consciousness, logically followed out, lead to this conclusion? Our purpose is, rather, to exhibit these assumptions themselves as untenable. Yet, so far we should have found only that it is possible for a premise to be false and yet for the conclusion drawn from it to be true. Granted that this may happen, yet we can never regard the conclusion as proved by means of that premise.