It is usual to apply the title of "Naïve Realism" to the theory which accepts as self-evident and indubitable the reality of the world-picture which is immediately given to us. The opposite theory, which regards this world as merely the content of our consciousness, is called "Transcendental Idealism." Hence, we may sum up the outcome of the above discussion by saying, "Transcendental Idealism demonstrates its own truth, by employing the premises of the Naïve Realism which it seeks to refute." Transcendental Idealism is true, if Naïve Realism is false. But the falsity of the latter is shown only by assuming it to be true. Once we clearly realise this situation, we have no choice but to abandon this line of argument and to try another. But are we to trust to good luck, and experiment about until we hit by accident upon the right line? This is Eduard von Hartmann's view when he believes himself to have shown the validity of his own epistemological standpoint, on the ground that his theory explains the phenomena whereas its rivals do not. According to his view, the several philosophical systems are engaged in a sort of struggle for existence in which the fittest is ultimately accepted as victor. But this method appears to us to be unsuitable, if only for the reason that there may well be several hypotheses which explain the phenomena equally satisfactorily. Hence, we had better keep to the above line of thought for the refutation of Naïve Realism, and see where precisely its deficiency lies. For, after all, Naïve Realism is the view from which we all start out. For this reason alone it is advisable to begin by setting it right. When we have once understood why it must be defective, we shall be led upon the right path with far greater certainty than if we proceed simply at haphazard.