Why did George Berkeley reject abstract general ideas?

George Berkeley rejected the notion of abstract general ideas because his empiricist philosophy held that all knowledge is derived from perception.12

For Berkeley, all objects of human knowledge are ideas or sense-data that are directly perceived by the mind. Because every idea is necessarily particular—representing a specific color, shape, or sensation—he argued that it is impossible to form an abstract idea that is general in nature (such as a general idea of a triangle that is neither equilateral, isosceles, nor scalene).12

Berkeley maintained that there is no "substrate" or material object underlying these ideas, nor is there any mental entity that can represent a universal abstraction. Instead, he argued that we use particular ideas to stand for a collection of other particular ideas through the use of language and signs. By denying the existence of abstract general ideas, Berkeley reinforced his core principle that reality consists entirely of minds and their perceived ideas, asserting that this view was more consistent with common sense than the complex, abstract theories of his predecessors.3245