Why are the subjective world and the objective world dialectically united? Because we wear a pair of colored glasses. We have to rely on our senses and brains to do science and to understand the world, our senses and brains have limitations like a pair of colored glasses.

Scientists don’t realize that they are wearing colored glasses when they see the world. If they see everything red, they assume that the physical world is made up of red elements. They don’t believe that the red color comes from their own glasses. Philosophers are aware of this, which is the Copernican Revolution of Kant: not that our understanding conforms to the object, but that the object conforms to our understanding.[3]

Why did Kant say that the object must conform to our understanding? The main reason is that we have to use abstract method of understanding. This abstract method is a pair of colored glasses that we have to wear.

What is a chicken plus a dog? Is it equal to two chickens or two dogs? Obviously neither. But we can say that one plus one equals two, because we have made abstraction first before we do this calculation. What does it mean when we say “one”? It is an abstraction of a chicken, a dog, a person, an earth, everything. Scientific research cannot do without formal logic, and the premise of formal logic is abstraction. So scientific research can never do without abstraction. The abstract process can only take place in the subjective world. In the objective world there are only concrete things, there are no abstract things. In the concrete objective world, no two leaves are the same, and one is never equal to one. In the abstract subjective world, one can be equal to one. So scientific research can never jump out of the subjective world.

According to Hegel, the abstract view of identity puts identity and difference in opposition, and regards identity as only formal, such as A is A, A cannot be both A and -A. Hegel said this view of identity is a one-sided and isolated analytical method, which is very ridiculous.[4] Lenin excerpted for several times and agreed with Hegel’s criticism of abstract and concrete identity in his