As we mature and develop more abstract and sophisticated concepts, the same basic processes, concept formation and measurement, apply at each succeeding level of the conceptual hierarchy. In a few cases, we may discover that differences in kind at a lower level may be explained by differences in degree at a higher conceptual level. For example, we learn when we get older that the qualitative difference between "red" and "blue" arises from a quantitative difference in the wavelengths of light emitted. In certain other cases, the opposite happens. Differences in degree at a lower level may lead to differences in kind on a more complex level—especially when we begin to distinguish categories of functional entities based on utilitarian characteristics. (We shall see an example in a moment.)

Nevertheless, at each stage of knowledge, objective differences in kind determine how we need to organize our concepts, while objective differences in degree for attributes of the same kind provide us with the basis for measurements.