Dualism is a worldview that has many well-known representatives and is still of importance until this day. A dualist assumes that there are two opposing worlds. There are many names for those two worlds, and the division can be different for the variations of dualism. Dualism originates from the two sources, through which the world flows into our mind: Observation and Intuition. Through those two sources we receive perceptions and concepts. If we start from here and assume that reality is divided into a real, perceivable sphere and an ideal, conceptual sphere, then we end up in dualism. Often the conceptual sphere is reduced to subjective imagination or Vorstellung, something we made up based on perceptions. The perceptions are often assumed to be objective. This way reality splits up in two worlds, in an outside-world and an inside-world, in matter and spirit. The dualist wants to know if there is a connection between those two worlds. He wants to describe how the two worlds can interact.
Alternatively, it is possible to deny one of the worlds. Then we get to the one-sided monism. The materialist rejects the spiritual world, he considers thinking to be a material process and the concepts to be not real, but a subjective description of properties that have no relevance for the world. The spiritualist rejects the material world, for him the sensory perceptions are a product of the spirit, not caused by anything real, but just an illusion. All versions of one-sided monism are characterized by emphasizing one of our two sources to the world and reducing reality to this one source. This way, questions regarding the relation of the two sources are avoided from the start.
The dualist differentiates between himself as the subject, the real object, our perception of said object and the concept, which for him is supposed to assign a perception to a real object. As a result, the process of Erkenntnis, which the holistic monism captures with just the two aspects of perception and concept, appears much more complicated in dualism. The reason behind this is that the separation of subject and object, which we experience with our perception, gets carried over into the rest of the world. Then we place ourselves in one world and the outside reality, which we can also name cosmos, in another world. When this approach is complemented with the claim that we have no direct access to the other world, then we postulate limits of Erkenntnis, or limits of knowledge. This worldview overlooks that we are a part of the cosmos, that we are embedded in it. Because of our perception we experience ourselves standing separate, facing the world. We found out that we can expand our perception with devices and sensors. We also found out that perception does not show us a complete picture of the world. But the dualist does not see a real connection of perception and concept. He refuses to accept the concept as a part of the cosmos. And he cannot, because he put the cosmos into his objective world and the concept into his subjective world.
The holistic monism does not make any hasty judgements about what is real. This worldview is based on what we find and proceeds from there. The world shows itself to us in the shape of perceptions and concepts. If we want to see reality, we need to combine those two streams of input. All our experience is a connection of perceptions and concepts, made by our thinking. When we become aware of this we know that these two aspects are also united in reality. We receive the aspects through two sources, and when we connect them by making use of our thinking power, then we know reality. There are no limits to this which cannot be overcome. All concepts are included in the idea of the universe. Our cognitive nature separates the concepts, isolates them, gives them clear definitions and lets them appear as an entity within a bigger network. Additionally, we fill the concepts with content through the assignment of sensory perceptions.
Our Weltbild needs to grow organically, it must spread from its trunk like a tree. If we wish to get high up into the sky and root deep down into the ground, then we cannot produce floating twigs and leaves in mid-air. We cannot grow deep roots detached from the trunk. We need to continuously grow, enrich our network of concepts and experience, and try to spread evenly.