In today’s polarised political landscape we see those we disagree with as aliens, believing in crazy ideas. Yet the moral and political convictions of both left and right can be traced  back to two ideals: harmony with the world, and individual autonomy. In turn those ideas stem from two fundamental ideas: that we can know the world, and that we can know our own minds. A third idea, that we can come to know the minds of others, could be what completes the other two ideas and enable us to overcome our conflicts, writes Linda Zagzebski.

For thousands of years two ideas have invigorated human civilization. These ideas are so simple, it is easy to overlook their tremendous power, and it is easy to forget that we did not always have them. One is the idea that the human mind can grasp the universe; the other is the idea that the human mind can grasp itself. The first idea dominated in the West until the 16^th-17^th centuries when there was a big shift, and the idea that the human mind can grasp itself became dominant. That shift changed everything: in philosophy, art, literature, science, and moral and political thought. The uneasy relationship between these ideas is the source of many cultural divisions and intellectual confusions, but it also reveals what we have in common.