One of these is that the thinkers may ignore each other's attitude about good and evil altogether, and each continue to indulge his own preferences, indifferent to what the other may feel or do. In such a {192} case we have a world with twice as much of the ethical quality in it as our moral solitude, only it is without ethical unity. The same object is good or bad there, according as you measure it by the view which this one or that one of the thinkers takes. Nor can you find any possible ground in such a world for saying that one thinker's opinion is more correct than the other's, or that either has the truer moral sense. Such a world, in short, is not a moral universe but a moral dualism. Not only is there no single point of view within it from which the values of things can be unequivocally judged, but there is not even a demand for such a point of view, since the two thinkers are supposed to be indifferent to each other's thoughts and acts. Multiply the thinkers into a pluralism, and we find realized for us in the ethical sphere something like that world which the antique sceptics conceived of,--in which individual minds are the measures of all things, and in which no one 'objective' truth, but only a multitude of 'subjective' opinions, can be found. But this is the kind of world with which the philosopher, so long as he holds to the hope of a philosophy, will not put up. Among the various ideals represented, there must be, he thinks, some which have the more truth or authority; and to these the others _ought_ to yield, so that system and subordination may reign. Here in the word 'ought' the notion of _obligation_ comes emphatically into view, and the next thing in order must be to make its meaning clear.