Why did Boas argue that cultures should not be ranked as higher or lower?

Franz Boas argued against ranking cultures in a hierarchy because he rejected the ethnocentric assumptions of 19th-century cultural evolutionism, which falsely arranged societies on a unilinear ladder from "savagery" to "civilization."12

Boas’s opposition was rooted in several key principles:

• Rejection of Universal Standards: He argued that there is no single, objective standard of achievement by which all cultures can be measured. Instead, he advocated for cultural relativism, the position that all surviving human groups have evolved equally and are fully capable of meeting the needs of their members.23
• Historical Particularism: Boas emphasized that each culture is the product of its own unique history and local environmental adaptations. He believed that anthropologists should focus on the exhaustive study of these particular characteristics rather than attempting to force diverse societies into artificial, predetermined stages of development.13
• Critique of Biological Determinism: He demonstrated that cultural differences are not the result of biological or racial capacity. By proving that culture is independent of biology, he dismantled the racist justifications used by evolutionists to label certain groups as "inferior."12

Ultimately, Boas maintained that the complexity of human history defies simple, universal laws of progress.2