What is an inviolable law that specifies the relation between primary and secondary qualities called?

The concept of an inviolable law that specifies the relationship between primary and secondary qualities is best described as a natural law. In philosophy, particularly in the context of the works of thinkers like John Locke, primary qualities are attributes that objects possess independently of any observer, such as shape, size, and motion. In contrast, secondary qualities are those that arise from the interaction of primary qualities with an observer's senses, such as color, taste, and sound.

Natural law refers to principles that are seen as universally applicable and inherent in the nature of the world. It posits that there are fundamental laws governing reality that are discoverable through reason and observation. This aligns with the inquiry into the relationship between primary and secondary qualities and emphasizes the objective nature of reality governed by these laws.

While physical law, moral law, and social law all have their distinct definitions and areas of application, they do not specifically describe the philosophical framework concerning the properties of objects as they relate to sensory experience in the same direct way that natural law does. Thus, the correct identification of this inviolable law is natural law.