The theory of diffusion has been criticized for being ethnocentric; it implies that people living in different places are not equally capable of innovation; that some people innovate and others copy. It has also been criticized for being speculative.
Today most anthropologists accept the fact that diffusion occurs, but reject the theory of diffusion as an explanation for cross-cultural similarities. The main criticism is that even when diffusion occurs, the theory does not explain why it occurs -- in other words, why some ideas or artefacts diffuse, and others do not. Moreover, it does not explain how in the course of diffusion traits may be assigned new uses and meanings.