It vs. You
The fundamental opposition in Buber’s theory is between the It and the You. For Buber, humans orient to the world by either treating the world as an object (It) or entering into a relation with the world (You). Whether something is perceived as an It or a You determined the “mode of existence” of the human subject, or “I.” Thus, I can have one of two modes of existence at any time. If my mode of existence is with an It, then I am distinct from the world, which is an exterior object for my use. If my mode of existence is with a You, then I am in relation with the world, and because I am completely immersed in this relation, I do not feel separated or isolated from the world. Over the course of I and Thou, Buber unpacks the consequences of each mode of existence. For instance, we may progress technologically by approaching the world as an "It," but we need to relate to a "You" in order to be fulfilled spiritually.
Experience vs. Relation
The fundamental distinction between It and You also creates a distinction between experience and relation. The world addressed as “It,” Buber says, is the world of experience. We stand apart from the world and simply observe what happens. This means the world of experience is also the world of the “past.” Rather than being immersed in the present, I am observing it as it is happening, which means I am distanced from the world. In contrast, the world of “You” is the world of relation. Now, we are active in the world and in dynamic “reciprocity” with it. That means we act on the world and the world acts on us. To summarize, the world of It is the world of objective experience and the past. The world of You is the world of relation in the present.
Objecthood vs. Spirit
The two different modes of existence, I-You and I-It, are not only different, but seem to compete with one another. The more I treat something as an object (It), the less I can be involved in a spiritual relation with You. As Buber writes, “The improvement of the ability to experience and use generally involves a decrease in man’s power to relate.” Unfortunately, we must treat the world as an object in order to survive, but we need the spiritual component in order to feel fulfilled. In order for the human species to progress, it requires using and experiencing the world. That’s how we make the world better shaped to our needs, which Buber calls making the world more “comfortable.” But the very thing that extends our life expectancy may diminish the quality of life, because it puts us out of touch with immersion in the world, the power to relate with one another and God.
Modes of Existence vs. Parts of the World
At the heart of Buber’s ontology is a binary pair: the It and the You. But this is different from the fundamental opposition in many other ontological and metaphysical philosophies. In these philosophies, the “twoness” of the world usually refers to the difference between the “real” world and then a world of “appearances.” Think about how there is the tree itself in the world and then the image of tree as it appears to our senses or is represented in language. For Buber, instead, there is no split between reality and appearance. The important distinction is not between the tree as it "really is" and the tree as it merely "appears to us." The distinction is in how we approach the tree (or the world in general): as an It, or as a You. We either perceive something as an objective It, or enter into immediate relation with You. This has consequences for Buber’s spiritual teachings, because it means we do not have to renounce parts of the world, as asceticism teaches, but rather orient to the wholeness of the world in a different way.
The “Sublime Melancholy”
In discussing the relation between You and It, Buber remarks that they are not two different kinds of objects, but rather two different ways of approaching objects. I can either be in relation with something or else observe it more objectively and from a distance. This produces, however, a “sublime melancholy” for humanity: “that every You must become an It in our world.” For Buber, this is the case because it is impossible to sustain complete relation with the spirit of the world. In order to survive as biological organisms, we have to manipulate and use the world, in order to meet our needs. Mankind has two great powers: to design our world, and to relate to it. But blessed with these powers, mankind finds itself torn between their opposition as well.
Human vs. Other Realms
Throughout I and Thou, Buber talks about three realms in which we can develop relations. The first is the sphere of nature, which includes plants, animals, and everything from “the stones to the stars.” The second is sphere of men, which is where human relations are formed. The third is the spiritual sphere, which includes our relations with things that are invisible to us. Although it is possible to develop an I-You relation in each of these realms, Buber claims that relations with humans more directly lead to relations with the eternal You, or the all-encompassing You that is also the name for God. This is because when we are relating to someone in conversation, there is a dynamic and immediate reciprocity. I speak and you respond, and I respond to you. This models all relations, which are defined by mutuality. But because of the nature of language, this form of relation is more obvious than the others.
Eternal You vs. God
Buber claims that all relations with a You converge in the “eternal You.” This is like the master You or the You that contains all the others. In this way, the eternal You is often Buber’s name for God. With God, “unconditional exclusiveness and unconditional inclusiveness are one.” God is exclusive because, like any You, we are completely and only immersed in this one relation. But in this case, the You is everything, the whole world and all of time. So we are consumed by the You but there is nothing excluded from it. We are immersed in a relation that includes all. In this way, Buber’s God is different from the God of some religions. For instance, when people pray “thy will be done” to God, they position themselves in a completely passive relation: God does all the work. Instead, Buber says God and I co-participate in a relation together.