Subjective Idealism necessarily arises if the common-sense theory of two worlds, the real outside the mind, and the ideal, copying it, within the mind, is pushed to its conclusion. The real, outside the mind, being inaccessible, falls away. The arguments of this Idealism, as Hume said, “admit of no answer and produce no conviction.” [1] But I {20} mention the idea, because I do not think that any one can really understand the problem of Logic, or indeed of science in general, without having thoroughly thought himself into the difficulty of Subjective Idealism. It is necessary to be wholly dissatisfied with common-sense theory, and with the notion of a ready-made world set up for us to copy in the mind, before the logical analysis of intellectual construction can have interest or meaning for us. And to produce this dissatisfaction is the value of Subjective Idealism. [1] Vol. iv. p. 176 (ed. of 1854), _Inquiry concerning Human Understanding_, sect. 12. {21} LECTURE II “JUDGMENT” AS THE CONSCIOUSNESS OF A WORLD _Defect of Subjective Idealism_ 1. The last lecture was devoted to explaining the distinction between the stream of presentations and the world as it is for knowledge. I ended by calling attention to the theory known as “Subjective Idealism.” This, I said, has the merit of forcing upon us the question, “How do we get from mind to reality? How do we get from subjective to objective?” For we have always to remember that our knowledge _is_ within consciousness, though it may _refer_ outside it. On the other hand, Subjective Idealism has the _defect_ of confounding the very distinction which we took so much trouble to make plain. Its essence lies in ascribing to the world of knowledge properties which are only true of the stream of presentation. It is quite true that the actual presentations of this room, which each of us has in his head at this moment, are all different from each other, and different from any which we have had before, and shall ever have again. Every minute, every second, they differ; they are perishing existences, wholly mental, and each of them when past is irrecoverably gone. That is the property of a presentation within the course of consciousness. It is a particular perishing existence. {22} But Subjective Idealism says, “Because these mental existences are particular perishing existences, and all knowledge consists in them as its medium, therefore the object of knowledge is nothing beyond these mental facts, and is not rooted in a permanent system [1] independent of our mental connections.” Here we must check the inference, and reply, “No, it does not follow. The presentations which themselves come and go may refer to something in common, and through them all we may become aware of something that is not wholly in any of them.” In other words, there is in Knowledge no passage _from_ subjective to objective, but only a development of the objective.